Programs & Examples On #Ncr

strange error in my Animation Drawable

Looks like whatever is in your Animation Drawable definition is too much memory to decode and sequence. The idea is that it loads up all the items and make them in an array and swaps them in and out of the scene according to the timing specified for each frame.

If this all can't fit into memory, it's probably better to either do this on your own with some sort of handler or better yet just encode a movie with the specified frames at the corresponding images and play the animation through a video codec.

Two Page Login with Spring Security 3.2.x

There should be three pages here:

  1. Initial login page with a form that asks for your username, but not your password.
  2. You didn't mention this one, but I'd check whether the client computer is recognized, and if not, then challenge the user with either a CAPTCHA or else a security question. Otherwise the phishing site can simply use the tendered username to query the real site for the security image, which defeats the purpose of having a security image. (A security question is probably better here since with a CAPTCHA the attacker could have humans sitting there answering the CAPTCHAs to get at the security images. Depends how paranoid you want to be.)
  3. A page after that that displays the security image and asks for the password.

I don't see this short, linear flow being sufficiently complex to warrant using Spring Web Flow.

I would just use straight Spring Web MVC for steps 1 and 2. I wouldn't use Spring Security for the initial login form, because Spring Security's login form expects a password and a login processing URL. Similarly, Spring Security doesn't provide special support for CAPTCHAs or security questions, so you can just use Spring Web MVC once again.

You can handle step 3 using Spring Security, since now you have a username and a password. The form login page should display the security image, and it should include the user-provided username as a hidden form field to make Spring Security happy when the user submits the login form. The only way to get to step 3 is to have a successful POST submission on step 1 (and 2 if applicable).

FragmentActivity to Fragment

first of all;

a Fragment must be inside a FragmentActivity, that's the first rule,

a FragmentActivity is quite similar to a standart Activity that you already know, besides having some Fragment oriented methods

second thing about Fragments, is that there is one important method you MUST call, wich is onCreateView, where you inflate your layout, think of it as the setContentLayout

here is an example:

    @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {     mView       = inflater.inflate(R.layout.fragment_layout, container, false);       return mView; } 

and continu your work based on that mView, so to find a View by id, call mView.findViewById(..);

for the FragmentActivity part:

the xml part "must" have a FrameLayout in order to inflate a fragment in it

        <FrameLayout             android:id="@+id/content_frame"             android:layout_width="match_parent"             android:layout_height="match_parent"  >         </FrameLayout> 

as for the inflation part

getSupportFragmentManager().beginTransaction().replace(, new YOUR_FRAGMENT, "TAG").commit();

begin with these, as there is tons of other stuf you must know about fragments and fragment activities, start of by reading something about it (like life cycle) at the android developer site

Why am I getting Unknown error in line 1 of pom.xml?

same problem for me, original code from spring starter demo gives unknown error on line 1:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="" xmlns:xsi=""
    <relativePath/> <!-- lookup parent from repository -->

Changing just the version of 2.1.6.RELEASE to 2.1.4.RELEASE fixes the problem.

What is useState() in React?

The syntax of useState hook is straightforward.

const [value, setValue] = useState(defaultValue)

If you are not familiar with this syntax, go here.

I would recommend you reading the documentation.There are excellent explanations with decent amount of examples.

import { useState } from 'react';_x000D_
function Example() {_x000D_
    // Declare a new state variable, which we'll call "count"_x000D_
    const [count, setCount] = useState(0);_x000D_
  // its up to you how you do it_x000D_
  const buttonClickHandler = e => {_x000D_
   // increment_x000D_
   // setCount(count + 1)_x000D_
   // decrement_x000D_
   // setCount(count -1)_x000D_
   // anything_x000D_
   // setCount(0)_x000D_
  return (_x000D_
          <p>You clicked {count} times</p>_x000D_
         <button onClick={buttonClickHandler}>_x000D_
             Click me_x000D_

WebView showing ERR_CLEARTEXT_NOT_PERMITTED although site is HTTPS

When you call "" your server figures that it's missing "www" so it redirects the call to "" and then to "", your WebView call is blocked at the first redirection as it's a "http" call. You can call "" instead and it will solve the issue.

ConvergenceWarning: Liblinear failed to converge, increase the number of iterations

Normally when an optimization algorithm does not converge, it is usually because the problem is not well-conditioned, perhaps due to a poor scaling of the decision variables. There are a few things you can try.

  1. Normalize your training data so that the problem hopefully becomes more well conditioned, which in turn can speed up convergence. One possibility is to scale your data to 0 mean, unit standard deviation using Scikit-Learn's StandardScaler for an example. Note that you have to apply the StandardScaler fitted on the training data to the test data.
  2. Related to 1), make sure the other arguments such as regularization weight, C, is set appropriately.
  3. Set max_iter to a larger value. The default is 1000.
  4. Set dual = True if number of features > number of examples and vice versa. This solves the SVM optimization problem using the dual formulation. Thanks @Nino van Hooff for pointing this out, and @JamesKo for spotting my mistake.
  5. Use a different solver, for e.g., the L-BFGS solver if you are using Logistic Regression. See @5ervant's answer.

Note: One should not ignore this warning.

This warning came about because

  1. Solving the linear SVM is just solving a quadratic optimization problem. The solver is typically an iterative algorithm that keeps a running estimate of the solution (i.e., the weight and bias for the SVM). It stops running when the solution corresponds to an objective value that is optimal for this convex optimization problem, or when it hits the maximum number of iterations set.

  2. If the algorithm does not converge, then the current estimate of the SVM's parameters are not guaranteed to be any good, hence the predictions can also be complete garbage.


In addition, consider the comment by @Nino van Hooff and @5ervant to use the dual formulation of the SVM. This is especially important if the number of features you have, D, is more than the number of training examples N. This is what the dual formulation of the SVM is particular designed for and helps with the conditioning of the optimization problem. Credit to @5ervant for noticing and pointing this out.

Furthermore, @5ervant also pointed out the possibility of changing the solver, in particular the use of the L-BFGS solver. Credit to him (i.e., upvote his answer, not mine).

I would like to provide a quick rough explanation for those who are interested (I am :)) why this matters in this case. Second-order methods, and in particular approximate second-order method like the L-BFGS solver, will help with ill-conditioned problems because it is approximating the Hessian at each iteration and using it to scale the gradient direction. This allows it to get better convergence rate but possibly at a higher compute cost per iteration. That is, it takes fewer iterations to finish but each iteration will be slower than a typical first-order method like gradient-descent or its variants.

For e.g., a typical first-order method might update the solution at each iteration like

x(k + 1) = x(k) - alpha(k) * gradient(f(x(k)))

where alpha(k), the step size at iteration k, depends on the particular choice of algorithm or learning rate schedule.

A second order method, for e.g., Newton, will have an update equation

x(k + 1) = x(k) - alpha(k) * Hessian(x(k))^(-1) * gradient(f(x(k)))

That is, it uses the information of the local curvature encoded in the Hessian to scale the gradient accordingly. If the problem is ill-conditioned, the gradient will be pointing in less than ideal directions and the inverse Hessian scaling will help correct this.

In particular, L-BFGS mentioned in @5ervant's answer is a way to approximate the inverse of the Hessian as computing it can be an expensive operation.

However, second-order methods might converge much faster (i.e., requires fewer iterations) than first-order methods like the usual gradient-descent based solvers, which as you guys know by now sometimes fail to even converge. This can compensate for the time spent at each iteration.

In summary, if you have a well-conditioned problem, or if you can make it well-conditioned through other means such as using regularization and/or feature scaling and/or making sure you have more examples than features, you probably don't have to use a second-order method. But these days with many models optimizing non-convex problems (e.g., those in DL models), second order methods such as L-BFGS methods plays a different role there and there are evidence to suggest they can sometimes find better solutions compared to first-order methods. But that is another story.

How to allow all Network connection types HTTP and HTTPS in Android (9) Pie?

The FULLY WORKING SOLUTION for both Android or React-native users facing this issue just add this android:usesCleartextTraffic="true" in AndroidManifest.xml file like this:

    android:required="false" />

in between <application>.. </application> tag like this:

            android:required="false" />

How to increase image size of pandas.DataFrame.plot in jupyter notebook?

Try figsize param in df.plot(figsize=(width,height)):

df = pd.DataFrame({"a":[1,2],"b":[1,2]})

enter image description here

df = pd.DataFrame({"a":[1,2],"b":[1,2]})

enter image description here

The size in figsize=(5,3) is given in inches per (width, height)

Default interface methods are only supported starting with Android N

As CommonsWare mentioned, for reference add this inside the android {...} closure in the build.gradle for your app module to resolve issue:

android {
  compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8

error: resource android:attr/fontVariationSettings not found

If you have stumbled upon this problem due to getting this error recently out of nowhere in react native- this is due to the latest BREAKING CHANGE in Google Play service and Firebase. Check this thread first -

And solution would mostly be like this -

After Spring Boot 2.0 migration: jdbcUrl is required with driverClassName

I have added in Application Class

public DataSource dataSource() {
    return DataSourceBuilder.create().build();
} I have added


More details Configure a Custom DataSource

Entity Framework Core: A second operation started on this context before a previous operation completed

The exception means that _context is being used by two threads at the same time; either two threads in the same request, or by two requests.

Is your _context declared static maybe? It should not be.

Or are you calling GetClients multiple times in the same request from somewhere else in your code?

You may already be doing this, but ideally, you'd be using dependency injection for your DbContext, which means you'll be using AddDbContext() in your Startup.cs, and your controller constructor will look something like this:

private readonly MyDbContext _context; //not static

public MyController(MyDbContext context) {
    _context = context;

If your code is not like this, show us and maybe we can help further.

Failed linking file resources

Look at the error you are getting:

C:\Projects\TimeTable\app\src\main\res\layout-land\activity_main.xml Error:error: resource android:attr/colorSwitchThumbNormal is private.

It means that in your activity_main.xml you are referencing the color "android:colorSwitchThumbNormal", but inside the 'android' namespace that resource is private. What you probably meant to do is try to reference that color from the support version of this attribute, so without the "android:" prefix.

<item name="android:colorSwitchThumbNormal">@color/myColor</item>

Replace with:

<item name="colorSwitchThumbNormal">@color/second</item>

Expected response code 250 but got code "530", with message "530 5.7.1 Authentication required

your mail.php on config you declare host as and port is 587 while on env is different. you need to change your mail.php to

'host' => env('MAIL_HOST', ''),
'port' => env('MAIL_PORT', 2525),

if you desire to use mailtrap.Then run

php artisan config:cache

Execution failed for task ':app:compileDebugJavaWithJavac' Android Studio 3.1 Update

I solved it by deleting "/.idea/libraries" from project. Thanks

How to shift a block of code left/right by one space in VSCode?

Recent versions of VSCode (e.g., Version 1.29 at the time of posting this answer) allow you to change the Tab/Space size to 1 (or any number between 1 and 8). You may change the Tab/Space size from the bottom-right corner as shown in the below image:

Change Tab/Space size

Click on Spaces:4. Then, select Indent Using Spaces or Indent Using Tabs and choose the size 1.

Hope it helps.

Exception : AAPT2 error: check logs for details

I fixed the ERROR with three steps
1. I checked for the problem SOURCE
2. Provided the correct string/text, because it was the CAUSE
3. I cleaned the project, you ll see it under BUILD.

enter image description here

java.lang.RuntimeException: Unable to merge dex in Android Studio 3.0

Enable Multidex through build.gradle of your app module

multiDexEnabled true

Same as below -

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId ""
        minSdkVersion 15
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        multiDexEnabled true //Add this
        testInstrumentationRunner ""
    buildTypes {
        release {
            shrinkResources true
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), ''

Then follow below steps -

  1. From the Build menu -> press the Clean Project button.
  2. When task completed, press the Rebuild Project button from the Build menu.
  3. From menu File -> Invalidate cashes / Restart

compile is now deprecated so it's better to use implementation or api

How to read file with async/await properly?

Since Node v11.0.0 fs promises are available natively without promisify:

const fs = require('fs').promises;
async function loadMonoCounter() {
    const data = await fs.readFile("monolitic.txt", "binary");
    return new Buffer(data);

phpMyAdmin ERROR: mysqli_real_connect(): (HY000/1045): Access denied for user 'pma'@'localhost' (using password: NO)

Add these lines to the file xampp\phpMyAdmin\

$cfg['Servers'][$i]['controluser'] = 'root'; 
$cfg['Servers'][$i]['controlpass'] = '';

Node - was compiled against a different Node.js version using NODE_MODULE_VERSION 51

I had a similar problem with robotjs. There were some deprecated code that required node v11, but I had already compiled electron code on v12. So I got basically the same error. Nothing here worked as I was basically trying to rebuild electron and my other dependencies into node v11 from v12.

Here is what I did (part of this is based on chitzui's answer, credit where credit is due):

  • Back up package.json
  • completely delete the node_modules folder
  • completely delete package_lock.json
  • delete package.json (will reinit later)
  • Close any open editors and other cmd windows that are in the project's directory.
  • run npm init to reinit package, then missing data with old backed up package.json
  • run npm i
  • fixed :)

Hope this helps.

git clone error: RPC failed; curl 56 OpenSSL SSL_read: SSL_ERROR_SYSCALL, errno 10054

This happens when you push first time without net connection or poor net connection.But when you try again using good connection 2,3 times problem will be solved.

How to increment a letter N times per iteration and store in an array?

Here is your solution for the problem,

$letter = array();
for ($i = 'A'; $i !== 'ZZ'; $i++){
        if(ord($i) % 2 != 0)
           $letter[] .= $i;

You need to get the ASCII value for that character which will solve your problem.

Here is ord doc and working code.

For your requirement, you can do like this,

for ($i = 'A'; $i !== 'ZZ'; ord($i)+$x){
  $letter[] .= $i;

Here set $x as per your requirement.

Kotlin Android start new Activity

How about this to consider encapsulation?

For example:

    override fun onCreate(savedInstanceState: Bundle?) {

        val title = intent.getStringExtra(EXTRA_TITLE) ?: EXTRA_TITLE_DEFAULT

            .add(, ContentsFragment.newInstance())

    // Omit...

    companion object {

        private const val EXTRA_TITLE = "extra_title"
        private const val EXTRA_TITLE_DEFAULT = "No title"

        fun newIntent(context: Context, title: String): Intent {
            val intent = Intent(context,
            intent.putExtra(EXTRA_TITLE, title)
            return intent

phpMyAdmin access denied for user 'root'@'localhost' (using password: NO)

Check /etc/phpmyadmin/config-db.php file

  1. Go to terminal
  2. run vi /etc/phpmyadmin/config-db.php
  3. check the information
  4. Hit Ctrl + X
  5. Try login to phpmyadmin again through the web using the information from the config file.

No Application Encryption Key Has Been Specified

In my case, I also needed to reset the cached config files:

php artisan key:generate
php artisan config:cache

Java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/exc/InvalidDefinitionException

If issue remains even after updating dependency version, then delete everything present under

And, make sure following dependencies are present:




More than one file was found with OS independent path 'META-INF/LICENSE'

I my app, I was adding the jar dependencies like this:

implementation files('libs/json-simple-1.1.1.jar')

But I realised that they were already added because of the following first line in dependencies:

implementation fileTree(include: ['*.jar'], dir: 'libs')

This line adds all the jars in lib folder to app dependency.

Hence after removing the extra dependency implementation files('libs/json-simple-1.1.1.jar')

it is working fine.

Android Room - simple select query - Cannot access database on the main thread

Just do the database operations in a separate Thread. Like this (Kotlin):

Thread {
   //Do your database´s operations here

How to make primary key as autoincrement for Room Persistence lib

@Entity(tableName = "user")
data class User(

@PrimaryKey(autoGenerate = true)  var id: Int?,
       var name: String,
       var dob: String,
       var address: String,
       var gender: String

Error:Execution failed for task ':app:compileDebugKotlin'. > Compilation error. See log for more details

Below changes worked for me

I change distribution URL, located in



dependencies {
    classpath ''
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

    // NOTE: Do not place your application dependencies here; they belong
    // in the individual module build.gradle files

kotlin version 1.2.71

How to push JSON object in to array using javascript

var postdata = {created_at: "2017-03-14T01:00:32Z", entry_id: 33358, field1: "4", field2: "4", field3: "0"};

var data = [];


Prevent content from expanding grid items

By default, a grid item cannot be smaller than the size of its content.

Grid items have an initial size of min-width: auto and min-height: auto.

You can override this behavior by setting grid items to min-width: 0, min-height: 0 or overflow with any value other than visible.

From the spec:

6.6. Automatic Minimum Size of Grid Items

To provide a more reasonable default minimum size for grid items, this specification defines that the auto value of min-width / min-height also applies an automatic minimum size in the specified axis to grid items whose overflow is visible. (The effect is analogous to the automatic minimum size imposed on flex items.)

Here's a more detailed explanation covering flex items, but it applies to grid items, as well:

This post also covers potential problems with nested containers and known rendering differences among major browsers.

To fix your layout, make these adjustments to your code:

.month-grid {
  display: grid;
  grid-template: repeat(6, 1fr) / repeat(7, 1fr);
  background: #fff;
  grid-gap: 2px;
  min-height: 0;  /* NEW */
  min-width: 0;   /* NEW; needed for Firefox */

.day-item {
  padding: 10px;
  background: #DFE7E7;
  overflow: hidden;  /* NEW */
  min-width: 0;      /* NEW; needed for Firefox */

jsFiddle demo

1fr vs minmax(0, 1fr)

The solution above operates at the grid item level. For a container level solution, see this post:

Modal width (increase)

Make sure your modal is not placed in a container, try to add the !important annotation if it's not changing the width from the original one.

"SSL certificate verify failed" using pip to install packages

I had same issue. I was trying to install mysqlclient for my Django project.

In my case the system date/time wasn't up-to date (Windows 8). That's causing the error. So, updated my system date time and ran the command pip install mysqlclient again. And it did the work.

Hope this would be helpful for those people who're executing all the commands out there (suggesting in other answers) without checking their system date/time.

Best way to import Observable from rxjs

Rxjs v 6.*

It got simplified with newer version of rxjs .

1) Operators

import {map} from 'rxjs/operators';

2) Others

import {Observable,of, from } from 'rxjs';

Instead of chaining we need to pipe . For example

Old syntax :

New Syntax:

source.pipe(map(), switchMap()).subscribe()

Note: Some operators have a name change due to name collisions with JavaScript reserved words! These include:

do -> tap,

catch -> catchError

switch -> switchAll

finally -> finalize

Rxjs v 5.*

I am writing this answer partly to help myself as I keep checking docs everytime I need to import an operator . Let me know if something can be done better way.

1) import { Rx } from 'rxjs/Rx';

This imports the entire library. Then you don't need to worry about loading each operator . But you need to append Rx. I hope tree-shaking will optimize and pick only needed funcionts( need to verify ) As mentioned in comments , tree-shaking can not help. So this is not optimized way.

public cache = new Rx.BehaviorSubject('');

Or you can import individual operators .

This will Optimize your app to use only those files :

2) import { _______ } from 'rxjs/_________';

This syntax usually used for main Object like Rx itself or Observable etc.,

Keywords which can be imported with this syntax

 Observable, Observer, BehaviorSubject, Subject, ReplaySubject

3) import 'rxjs/add/observable/__________';

Update for Angular 5

With Angular 5, which uses rxjs 5.5.2+

import { empty } from 'rxjs/observable/empty';
import { concat} from 'rxjs/observable/concat';

These are usually accompanied with Observable directly. For example


Other such keywords which can be imported using this syntax:

concat, defer, empty, forkJoin, from, fromPromise, if, interval, merge, of, 
range, throw, timer, using, zip

4) import 'rxjs/add/operator/_________';

Update for Angular 5

With Angular 5, which uses rxjs 5.5.2+

import { filter } from 'rxjs/operators/filter';
import { map } from 'rxjs/operators/map';

These usually come in the stream after the Observable is created. Like flatMap in this code snippet:

          .flatMap(arr => Observable.from(arr));

Other such keywords using this syntax:

audit, buffer, catch, combineAll, combineLatest, concat, count, debounce, delay, 
distinct, do, every, expand, filter, finally, find , first, groupBy,
ignoreElements, isEmpty, last, let, map, max, merge, mergeMap, min, pluck, 
publish, race, reduce, repeat, scan, skip, startWith, switch, switchMap, take, 
takeUntil, throttle, timeout, toArray, toPromise, withLatestFrom, zip

FlatMap: flatMap is alias to mergeMap so we need to import mergeMap to use flatMap.

Note for /add imports :

We only need to import once in whole project. So its advised to do it at a single place. If they are included in multiple files, and one of them is deleted, the build will fail for wrong reasons.

How do I get rid of the b-prefix in a string in python?

Assuming you don't want to immediately decode it again like others are suggesting here, you can parse it to a string and then just strip the leading 'b and trailing '.

>>> x = "Hi there " 
>>> x = "Hi there ".encode("utf-8") 
>>> x
b"Hi there \xef\xbf\xbd"
>>> str(x)[2:-1]
"Hi there \\xef\\xbf\\xbd"   

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled

I added @Component annotation from import org.springframework.stereotype.Component and the problem was solved.

mcrypt is deprecated, what is the alternative?

I am using this on PHP 7.2.x, it's working fine for me:

public function make_hash($userStr){
             * Used and tested on PHP 7.2x, Salt has been removed manually, it is now added by PHP 
             return password_hash($userStr, PASSWORD_BCRYPT);
            }catch(Exception $exc){
                $this->tempVar = $exc->getMessage();
                return false;

and then authenticate the hash with the following function:

public function varify_user($userStr,$hash){
            if (password_verify($userStr, $hash)) {
                 return true;
            else {
                return false;
            }catch(Exception $exc){
                $this->tempVar = $exc->getMessage();
                return false;


  //create hash from user string

 $user_password = $obj->make_hash2($user_key);

and to authenticate this hash use the following code:

if($obj->varify_user($key, $user_key)){
      //this is correct, you can proceed with  

That's all.

Caused by: org.flywaydb.core.api.FlywayException: Validate failed. Migration Checksum mismatch for migration 2

IF YOU ARE NOT IN PRODUCTION, you can look in your flywayTable in the data base and remove the line which contain the name of the script which has been applied.

flywayTable is a project option which define the name of the table in the db used by flyway which contain information about the version of this db, already applied scripts...

Spring Boot Java Config Set Session Timeout

You should be able to set the server.session.timeout in your file.


Changing background color of selected item in recyclerview

A really simple way to achieve this would be:

//instance variable
List<View>itemViewList = new ArrayList<>();

public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {    
    final View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_row, parent, false);
    final MyViewHolder myViewHolder = new MyViewHolder(itemView);

    itemViewList.add(itemView); //to add all the 'list row item' views

    //Set on click listener for each item view
    itemView.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            for(View tempItemView : itemViewList) {
                /** navigate through all the itemViews and change color
                of selected view to colorSelected and rest of the views to colorDefault **/
                if(itemViewList.get(myViewHolder.getAdapterPosition()) == tempItemView) {
    return myViewHolder;


The method above may ruin some default attributes of the itemView, in my case, i was using CardView, and the corner radius of the card was getting removed on click.

Better solution:

//instance variable
List<CardView>cardViewList = new ArrayList<>();

public class MyViewHolder extends RecyclerView.ViewHolder {
        CardView cardView; //THIS IS MY ROOT VIEW

        public MyViewHolder(View view) {
            cardView = view.findViewById(;

    public void onBindViewHolder(final MyViewHolder holder, int position) {
        final OurLocationObject locationObject = locationsList.get(position);

        cardViewList.add(holder.cardView); //add all the cards to this list

        holder.cardView.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                //All card color is set to colorDefault
                for(CardView cardView : cardViewList){
                //The selected card is set to colorSelected


onBindViewHolder method is called multiple times, and also every time the user scrolls the view out of sight and back in sight! This will cause the same view to be added to the list multiple times which may cause problems and minor delay in code executions!

To fix this, change



if (!cardViewList.contains(holder.cardView)) {

Kubernetes how to make Deployment to update image

UPDATE 2019-06-24

Based on the @Jodiug comment if you have a 1.15 version you can use the command:

kubectl rollout restart deployment/demo

Read more on the issue:

Well there is an interesting discussion about this subject on the kubernetes GitHub project. See the issue:

From the solutions described there, I would suggest one of two.


1.Prepare deployment

apiVersion: extensions/v1beta1
kind: Deployment
  name: demo
  replicas: 1
        app: demo
      - name: demo
        imagePullPolicy: Always


sed -ie "s/THIS_STRING_IS_REPLACED_DURING_BUILD/$(date)/g" deployment.yml
kubectl apply -f deployment.yml

Second (one liner):

kubectl patch deployment web -p \
  "{\"spec\":{\"template\":{\"metadata\":{\"labels\":{\"date\":\"`date +'%s'`\"}}}}}"

Of course the imagePullPolicy: Always is required on both cases.

How to request Location Permission at runtime

After having it defined in your manifest file, a friendlier alternative to the native solution would be using Aaper: like so:

@EnsurePermissions(permissions = [Manifest.permission.ACCESS_FINE_LOCATION])
private fun scanForLocation() {
    // Your code that needs the location permission granted.

Disclaimer, I'm the creator of Aaper.

Default FirebaseApp is not initialized

use' instead of 4.1.0

Error creating bean with name 'entityManagerFactory' defined in class path resource : Invocation of init method failed

Adding dependencies didn't fix the issue at my end.

The issue was happening at my end because of "additional" fields that are part of the "@Entity" class and don't exist in the database.

I removed the additional fields from the @Entity class and it worked.


Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path $

I solved this problem very easily after finding out this happens when you aren't outputting a proper JSON object, I simply used the echo json_encode($arrayName); instead of print_r($arrayName); With my php api.

Every programming language or at least most programming languages should have their own version of the json_encode() and json_decode() functions.

Spark RDD to DataFrame python

I liked Arun's answer better but there is a tiny problem and I could not comment or edit the answer. sparkContext does not have createDeataFrame, sqlContext does (as Thiago mentioned). So:

from pyspark.sql import SQLContext

# assuming the spark environemnt is set and sc is spark.sparkContext 
sqlContext = SQLContext(sc)
schemaPeople = sqlContext.createDataFrame(RDDName)

gzip: stdin: not in gzip format tar: Child returned status 1 tar: Error is not recoverable: exiting now

Initially, check the type of compression with the below command: file <file_name> If the output is a Posix compressed file, use the below command to uncompress: tar xvf <file_name>

How do I increase the contrast of an image in Python OpenCV

I would like to suggest a method using the LAB color channel. Wikipedia has enough information regarding what the LAB color channel is about.

I have done the following using OpenCV 3.0.0 and python:

import cv2

#-----Reading the image-----------------------------------------------------
img = cv2.imread('Dog.jpg', 1)

#-----Converting image to LAB Color model----------------------------------- 
lab= cv2.cvtColor(img, cv2.COLOR_BGR2LAB)

#-----Splitting the LAB image to different channels-------------------------
l, a, b = cv2.split(lab)
cv2.imshow('l_channel', l)
cv2.imshow('a_channel', a)
cv2.imshow('b_channel', b)

#-----Applying CLAHE to L-channel-------------------------------------------
clahe = cv2.createCLAHE(clipLimit=3.0, tileGridSize=(8,8))
cl = clahe.apply(l)
cv2.imshow('CLAHE output', cl)

#-----Merge the CLAHE enhanced L-channel with the a and b channel-----------
limg = cv2.merge((cl,a,b))
cv2.imshow('limg', limg)

#-----Converting image from LAB Color model to RGB model--------------------
final = cv2.cvtColor(limg, cv2.COLOR_LAB2BGR)
cv2.imshow('final', final)


You can run the code as it is. To know what CLAHE (Contrast Limited Adaptive Histogram Equalization)is about, you can again check Wikipedia.

How to register multiple implementations of the same interface in Asp.Net Core?

I didn't have time to read through them all but it seemed everyone was providing solutions to problems that shouldn't exist in the first place.

If you need all of the registered IService implementations then you need them all. But DO NOT inject them all with IEnumerable and then use logic to select one based on some type of key. Problem with doing that is you need a key and the logic should not need to change if the key changes ie; different implementation of IService so typeof doesn't work any more.

The Real Problem

There is business logic here that should be in an engine service. Something like IServiceDecisionEngine is needed. The implementation of the IServiceDecisionEngine gets ONLY the needed IService implementations from DI. Like

public class ServiceDecisionEngine<SomeData>: IServiceDecisionEngine<T> 
    public ServiceDecisionEngine(IService serviceA, IService serviceB) { }

    public IService ResolveService(SomeData dataNeededForLogic)
        if (dataNeededForLogic.someValue == true) 
            return serviceA;
        return serviceB;

Now in your DI, you can do .AddScoped<IServiceDecisionEngine<SomeData>, new ServiceDecisionEngine(new ServiceA(), new ServiceB()) and the managerService that needs an IService will get it by injecting and using IServiceDecisionEngine.

How do I release memory used by a pandas dataframe?

This solves the problem of releasing the memory for me!!!

import gc
import pandas as pd

del [[df_1,df_2]]

the data-frame will be explicitly set to null

in the above statements

Firstly, the self reference of the dataframe is deleted meaning the dataframe is no longer available to python there after all the references of the dataframe is collected by garbage collector (gc.collect()) and then explicitly set all the references to empty dataframe.

more on the working of garbage collector is well explained in

How to Add Incremental Numbers to a New Column Using Pandas


df = df.reset_index()
df.columns[0] = 'New_ID'
df['New_ID'] = df.index + 880

The Response content must be a string or object implementing __toString(), "boolean" given after move to psql

So, rather return the whole object first, just wrap it to json_encode and then return it. This will return a proper and valid object.

public function id($id){
    $promotion = Promotion::find($id);
    return json_encode($promotion);

Or, For DB this will be just like,

public function id($id){
    $promotion = DB::table('promotions')->first();
    return json_encode($promotion);

I think it may help someone else.

How to fix error Base table or view not found: 1146 Table laravel relationship table?

For solving your Base Table or view not found error you can do As @Alexey Mezenin said that change table name category_post to category_posts,

but if you don't want to change the name like in my case i am using inventory table so i don't want to suffix it by s so i will provide table name in model as protected $table = 'Table_name_as_you_want' and then there is no need to change table name:

Change your Model of the module in which you are getting error for example:


namespace App;

use Illuminate\Database\Eloquent\Model;

class Inventory extends Model
    protected $table = 'inventory';

    protected $fillable = [
        'supply', 'order',

you have to provide table name in model then it will not give error.

Letsencrypt add domain to existing certificate

this worked for me

 sudo letsencrypt certonly -a webroot --webroot-path=/var/www/html -d -d

How do you send a Firebase Notification to all devices via CURL?

Your can send notification to all devices using "/topics/all"

  "to": "/topics/all",
  "notification":{ "title":"Notification title", "body":"Notification body", "sound":"default", "click_action":"FCM_PLUGIN_ACTIVITY", "icon":"fcm_push_icon" },
  "data": {
    "message": "This is a Firebase Cloud Messaging Topic Message!",

Class file for not found

I solved this exact problem today and stumbled onto this unanswered question by chance during the process.

First, ensure you've properly setup Firebase for Android as documented here: Then, make sure you are compiling the latest version of the Firebase APIs (9.2.0) and the Google Play Services APIs (9.2.0) that you are using. My gradle dependencies look something like this:

dependencies {
    compile ''
    compile ''
    compile ''
    compile ''

Hope this helps! /storage/emulated/0/New file.txt: open failed: EACCES (Permission denied)

Implement runtime permission for running your app on Android 6.0 Marshmallow (API 23) or later.

or you can manually enable the storage permission-

goto settings>apps> "your_app_name" >click on it >then click permissions> then enable the storage. Thats it.

But i suggest go the for first one which is, Implement runtime permissions in your code.

Iterating over Typescript Map

Just a simple explanation to use it in an HTML document.

If you have a Map of types (key, array) then you initialise the array this way:

public cityShop: Map<string, Shop[]> = new Map();

And to iterate over it, you create an array from key values.

Just use it as an array as in:

keys = Array.from(this.cityShop.keys());

Then, in HTML, you can use:

*ngFor="let key of keys"

Inside this loop, you just get the array value with:



how to get docker-compose to use the latest image from repository

I spent half a day with this problem. The reason was that be sure to check where the volume was recorded.

volumes: - api-data:/src/patterns

But the fact is that in this place was the code that we changed. But when updating the docker, the code did not change.

Therefore, if you are checking someone else's code and for some reason you are not updating, check this.

And so in general this approach works:

docker-compose down

docker-compose build

docker-compose up -d

How to configure Spring Security to allow Swagger URL to be accessed without authentication

For those who using a newer swagger 3 version org.springdoc:springdoc-openapi-ui

public class WebSecurityConfiguration extends WebSecurityConfigurerAdapter {

    public void configure(WebSecurity web) throws Exception {
        web.ignoring().antMatchers("/v3/api-docs/**", "/swagger-ui.html", "/swagger-ui/**");

Laravel migration default value

You can simple put the default value using default(). See the example

 $table->enum('is_approved', array('0','1'))->default('0');

I have used enum here and the default value is 0.

org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:transformClassesWithDexForDebug'

I had the same issue and I could solve it like this:

1) If your minSdkVersion is set to 21 or a higher value, the only thing you need to do is to set multiDexEnabled in your build.gradle file at the module level, as shown below:

android {
    defaultConfig {
        minSdkVersion 21 
        targetSdkVersion 28
        multiDexEnabled true

2) However, if your minSdkVersion is set to 20 or less, you should use the MultiDex compatibility library, as follows:

2.1) Modify the module-level build.gradle file to enable MultiDex and add the MultiDex library as dependency, as shown below

android {
    defaultConfig {
        minSdkVersion 15 
        targetSdkVersion 28
        multiDexEnabled true

dependencies {
  implementation ''

2.2) According to the Application class or not, do one of the following actions:

2.2.1) If you do not cancel the Application class, modify your manifest file to set android: name in the <application> tag as shown below:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android=""
            android:name="" >

2.2.2) If you cancel the Application class, you must change it to extend MultiDexApplication (if possible) as shown below:

public class MyApplication extends MultiDexApplication { ... }

2.2.3) Also, if you override the Application class and can not change the base class, alternatively you can override the attachBaseContext () method and invoke MultiDex.install (this) to enable MultiDex:

public class MyApplication extends SomeOtherApplication {
  protected void attachBaseContext(Context base) {

Please use this link, it was really useful for me!

Python PIP Install throws TypeError: unsupported operand type(s) for -=: 'Retry' and 'int'

This is the working solution to this problem I found.

sudo apt-get clean
cd /var/lib/apt
sudo mv lists lists.old
sudo mkdir -p lists/partial
sudo apt-get clean
sudo apt-get update

JPA Hibernate Persistence exception [PersistenceUnit: default] Unable to build Hibernate SessionFactory

I found some issue about that kind of error

  1. Database username or password not match in the mysql or other other database. Please set like this


# =============================== # = DATA SOURCE # =============================== # Set here configurations for the database connection # Connection url for the database please let me know "[email protected]" spring.datasource.url = jdbc:mysql://localhost:3306/bookstoreapiabc # Username and secret spring.datasource.username = root spring.datasource.password = # Keep the connection alive if idle for a long time (needed in production) spring.datasource.testWhileIdle = true spring.datasource.validationQuery = SELECT 1 # =============================== # = JPA / HIBERNATE # =============================== # Use* for Hibernate native properties (the prefix is # stripped before adding them to the entity manager). # Show or not log for each sql query = true # Hibernate ddl auto (create, create-drop, update): with "update" the database # schema will be automatically updated accordingly to java entities found in # the project spring.jpa.hibernate.ddl-auto = update # Allows Hibernate to generate SQL optimized for a particular DBMS = org.hibernate.dialect.MySQL5Dialect

Issue no 2.

Your local server has two database server and those database server conflict. this conflict like this mysql server & xampp or lampp or wamp server. Please one of the database like mysql server because xampp or lampp server automatically install mysql server on this machine

CSS3 100vh not constant in mobile browser

For me such trick made a job:

height: calc(100vh - calc(100vh - 100%))

Does WhatsApp offer an open API?

1) It looks possible. This info on Github describes how to create a java program to send a message using the whatsapp encryption protocol from WhisperSystems.

2) No. See the whatsapp security white paper.

3) See #1.

Remove 'b' character do in front of a string literal in Python 3

This should do the trick:


How to pass a user / password in ansible command

you can use --extra-vars like this:

$ ansible all --inventory=, -m ping \
    --extra-vars "ansible_user=root ansible_password=yourpassword"

If you're authenticating to a Linux host that's joined to a Microsoft Active Directory domain, this command line works.

ansible --module-name ping --extra-vars 'ansible_user=domain\user ansible_password=PASSWORD' --inventory, all

How do I filter an array with TypeScript in Angular 2?

To filter an array irrespective of the property type (i.e. for all property types), we can create a custom filter pipe

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({ name: "filter" })
export class ManualFilterPipe implements PipeTransform {
  transform(itemList: any, searchKeyword: string) {
    if (!itemList)
      return [];
    if (!searchKeyword)
      return itemList;
    let filteredList = [];
    if (itemList.length > 0) {
      searchKeyword = searchKeyword.toLowerCase();
      itemList.forEach(item => {
        //Object.values(item) => gives the list of all the property values of the 'item' object
        let propValueList = Object.values(item);
        for(let i=0;i<propValueList.length;i++)
          if (propValueList[i]) {
            if (propValueList[i].toString().toLowerCase().indexOf(searchKeyword) > -1)
    return filteredList;


//<tr *ngFor="let company of companyList | filter: searchKeyword"></tr>

Don't forget to import the pipe in the app module

We might need to customize the logic to filer with dates.

Error while waiting for device: Time out after 300seconds waiting for emulator to come online

Upgrade to the latest SDK, for the android emulator:

  • use 512MB RAM
  • 256MB heap

You can leave the default disk space.

Session 'app': Error Launching activity

Same issue, but for me problem was that Android Studio couldn't find my Default Activity. When I specified the intent filter to catch the MAIN action intent, I didn't specify the LAUNCHER category, and that caused the 'Error Launching activity' issue.

        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />  <-- forgot

Failed to load ApplicationContext (with annotation)

In my case, I had to do the following while running with Junit5

@SpringBootTest(classes = {abc.class}) @ExtendWith(SpringExtension.class

Here abc.class was the class that was being tested

Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]

Either you experienced database connection issue or you missed any of the hibernate configurations to connect to database such as database DIALECT.

Happens if your database server was disconnected due to network related issue.

If you're using spring boot along with hibernate connected to Oracle Db, use

entitymanager.packagesToScan: com

How to remove title bar from the android activity?

you just add this style in your style.xml file which is in your values folder

<style name="AppTheme.NoActionBar" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>
    <item name="android:windowFullscreen">true</item>

After that set this style to your activity class in your AndroidManifest.xml file


Edit:- If you are going with programmatic way to hide ActionBar then use below code in your activity onCreate() method.


and if you want to hide ActionBar from Fragment then


AppCompat v7:- Use following theme in your Activities where you don't want actiobBar Theme.AppComat.NoActionBar or Theme.AppCompat.Light.NoActionBar or if you want to hide in whole app then set this theme in your <application... /> in your AndroidManifest.

In Kotlin:

add this line of code in your onCreate() method or you can use above theme.

if (supportActionBar != null)

i hope this will help you more.

Auto-increment on partial primary key with Entity Framework Core

Specifying the column type as serial for PostgreSQL to generate the id.

[Column(Order=1, TypeName="serial")]
public int ID { get; set; }

Could not autowire field:RestTemplate in Spring boot application

Please make sure two things:

1- Use @Bean annotation with the method.

public RestTemplate restTemplate(RestTemplateBuilder builder){

2- Scope of this method should be public not private.

Complete Example -

public class MakeHttpsCallImpl implements MakeHttpsCall {

private RestTemplate restTemplate;

public String makeHttpsCall() {
    return restTemplate.getForObject("https://localhost:8085/onewayssl/v1/test",String.class);

public RestTemplate restTemplate(RestTemplateBuilder builder){

Android- Error:Execution failed for task ':app:transformClassesWithDexForRelease'

For me, this turned out to be an unimplemented parcelable class with no datatype [Any]; due to which there was a TODO() constructor created in parcelable implementation of model class.

Hope it helps someone.

var firstTxnDetails: Any? = Any()

//in parcelable implementation :

constructor(parcel: Parcel) : this(
            TODO("firstTxnDetails"), // -> correct this
            parcel.readString()) {

ITSAppUsesNonExemptEncryption export compliance while internal testing?

The same error solved like this

enter image description here

    using UnityEngine;
    using System.Collections;
    using UnityEditor.Callbacks;
    using UnityEditor;
    using System;
    using UnityEditor.iOS.Xcode;
    using System.IO;

public class AutoIncrement : MonoBehaviour {

    public static void ChangeXcodePlist(BuildTarget buildTarget, string pathToBuiltProject)

        if (buildTarget == BuildTarget.iOS)

            // Get plist
            string plistPath = pathToBuiltProject + "/Info.plist";
            var plist = new PlistDocument();

            // Get root
            var rootDict = plist.root;

            // Change value of NSCameraUsageDescription in Xcode plist
            var buildKey = "NSCameraUsageDescription";
            rootDict.SetString(buildKey, "Taking screenshots");

            var buildKey2 = "ITSAppUsesNonExemptEncryption";
            rootDict.SetString(buildKey2, "false");

            // Write to file
            File.WriteAllText(plistPath, plist.WriteToString());
    // Use this for initialization
    void Start () {


    // Update is called once per frame
    void Update () {


    public static void OnPostprocessBuild(BuildTarget target, string pathToBuiltProject)
        //A new build has happened so lets increase our version number

    // Bump version number in PlayerSettings.bundleVersion
    private static void BumpBundleVersion()
        float versionFloat;

        if (float.TryParse(PlayerSettings.bundleVersion, out versionFloat))
            versionFloat += 0.01f;
            PlayerSettings.bundleVersion = versionFloat.ToString();
    [MenuItem("Leman/Build iOS Development", false, 10)]
    public static void CustomBuild()
        var levels= new String[] { "Assets\\ShootTheBall\\Scenes\\MainScene.unity" };
            "iOS", BuildTarget.iOS, BuildOptions.Development);


How to set menu to Toolbar in Android

You can still use the answer provided using Toolbar.inflateMenu even while using setSupportActionBar(toolbar).

I had a scenario where I had to move toolbar setup functionality into a separate class outside of activity which didn't by-itself know of the event onCreateOptionsMenu.

So, to implement this, all I had to do was wait for Toolbar to be drawn before calling inflateMenu by doing the following: {

Might not be considered very clean but still gets the job done.

MySQL Incorrect datetime value: '0000-00-00 00:00:00'

You can change the type of created field from datetime to varchar(255), then you can set (update) all records that have the value "0000-00-00 00:00:00" to NULL.

Now, you can do your queries without error. After you finished, you can alter the type of the field created to datetime.

PostgreSQL: role is not permitted to log in

try to run

sudo su - postgres
ALTER ROLE 'dbname'

android: data binding error: cannot find symbol class

You must change your activity_contact_list to be binded - add layout tag as you did in content_contact_list. Don't forget, The root layout inside activity_contact_list must have an id for the Binding class to be generated and will be named ActivityContactListBinding (i.e. the name of the layout with camel casting instead of underscores).

Next, inside activity_contact_list, give <include layout="@layout/content_contact_list" /> an id, then you will have access for its binding instance through your ActivityContactListBinding instance.

Somthing like:


Let me know if it works.

How to read pickle file?

Pickle serializes a single object at a time, and reads back a single object - the pickled data is recorded in sequence on the file.

If you simply do pickle.load you should be reading the first object serialized into the file (not the last one as you've written).

After unserializing the first object, the file-pointer is at the beggining of the next object - if you simply call pickle.load again, it will read that next object - do that until the end of the file.

objects = []
with (open("myfile", "rb")) as openfile:
    while True:
        except EOFError:

Is there a simple way to increment a datetime object one month in Python?

Check out from dateutil.relativedelta import * for adding a specific amount of time to a date, you can continue to use timedelta for the simple stuff i.e.

use_date = use_date + datetime.timedelta(minutes=+10)
use_date = use_date + datetime.timedelta(hours=+1)
use_date = use_date + datetime.timedelta(days=+1)
use_date = use_date + datetime.timedelta(weeks=+1)

or you can start using relativedelta

use_date = use_date+relativedelta(months=+1)

use_date = use_date+relativedelta(years=+1)

for the last day of next month:

use_date = use_date+relativedelta(months=+1)
use_date = use_date+relativedelta(day=31)

Right now this will provide 29/02/2016

for the penultimate day of next month:

use_date = use_date+relativedelta(months=+1)
use_date = use_date+relativedelta(day=31)
use_date = use_date+relativedelta(days=-1)

last Friday of the next month:

use_date = use_date+relativedelta(months=+1, day=31, weekday=FR(-1))

2nd Tuesday of next month:

new_date = use_date+relativedelta(months=+1, day=1, weekday=TU(2))

As @mrroot5 points out dateutil's rrule functions can be applied, giving you an extra bang for your buck, if you require date occurences.
for example:
Calculating the last day of the month for 9 months from the last day of last month.
Then, calculate the 2nd Tuesday for each of those months.

from dateutil.relativedelta import *
from dateutil.rrule import *
from datetime import datetime
use_date = datetime(2020,11,21)

#Calculate the last day of last month
use_date = use_date+relativedelta(months=-1)
use_date = use_date+relativedelta(day=31)

#Generate a list of the last day for 9 months from the calculated date
x = list(rrule(freq=MONTHLY, count=9, dtstart=use_date, bymonthday=(-1,)))
print("Last day")
for ld in x:

#Generate a list of the 2nd Tuesday in each of the next 9 months from the calculated date
print("\n2nd Tuesday")
x = list(rrule(freq=MONTHLY, count=9, dtstart=use_date, byweekday=TU(2)))
for tuesday in x:

Last day
2020-10-31 00:00:00
2020-11-30 00:00:00
2020-12-31 00:00:00
2021-01-31 00:00:00
2021-02-28 00:00:00
2021-03-31 00:00:00
2021-04-30 00:00:00
2021-05-31 00:00:00
2021-06-30 00:00:00

2nd Tuesday
2020-11-10 00:00:00
2020-12-08 00:00:00
2021-01-12 00:00:00
2021-02-09 00:00:00
2021-03-09 00:00:00
2021-04-13 00:00:00
2021-05-11 00:00:00
2021-06-08 00:00:00
2021-07-13 00:00:00

This is by no means an exhaustive list of what is available. Documentation is available here:

How to use data-binding with Fragment

working in my code.

private FragmentSampleBinding dataBiding;
private SampleListAdapter mAdapter;

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    super.onCreateView(inflater, container, savedInstanceState);
    dataBiding = DataBindingUtil.inflate(inflater, R.layout.fragment_sample, null, false);
    return mView = dataBiding.getRoot();

Can't push image to Amazon ECR - fails with "no basic auth credentials"

aws ecr get-login --region us-west-1 --no-include-email

This command gives me correct command to login. If you dont use "--no-include-email",it will throw another error. Output of the above command looks like this docker login -u AWS -p **********************very big******. Copy that and execute it. Now it will show "Login Succeeded". Now you can push your image to ECR.

Make sure that your AMI rule has the permission for the user you tried to login.

Android Studio Gradle: Error:Execution failed for task ':app:processDebugGoogleServices'. > No matching client found for package

I think because your are using play-service 8.4.0

It required

classpath ''
classpath ''

you may also refer this.

How can I show current location on a Google Map on Android Marshmallow?

For using FusedLocationProviderClient with Google Play Services 11 and higher:

see here: How to get current Location in GoogleMap using FusedLocationProviderClient

For using (now deprecated) FusedLocationProviderApi:

If your project uses Google Play Services 10 or lower, using the FusedLocationProviderApi is the optimal choice.

The FusedLocationProviderApi offers less battery drain than the old open source LocationManager API. Also, if you're already using Google Play Services for Google Maps, there's no reason not to use it.

Here is a full Activity class that places a Marker at the current location, and also moves the camera to the current position.

It also checks for the Location permission at runtime for Android 6 and later (Marshmallow, Nougat, Oreo). In order to properly handle the Location permission runtime check that is necessary on Android M/Android 6 and later, you need to ensure that the user has granted your app the Location permission before calling mGoogleMap.setMyLocationEnabled(true) and also before requesting location updates.

public class MapLocationActivity extends AppCompatActivity
        implements OnMapReadyCallback,
        LocationListener {

    GoogleMap mGoogleMap;
    SupportMapFragment mapFrag;
    LocationRequest mLocationRequest;
    GoogleApiClient mGoogleApiClient;
    Location mLastLocation;
    Marker mCurrLocationMarker;

    protected void onCreate(Bundle savedInstanceState)

        getSupportActionBar().setTitle("Map Location Activity");

        mapFrag = (SupportMapFragment) getSupportFragmentManager().findFragmentById(;

    public void onPause() {

        //stop location updates when Activity is no longer active
        if (mGoogleApiClient != null) {
            LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);

    public void onMapReady(GoogleMap googleMap)

        //Initialize Google Play Services
        if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (ContextCompat.checkSelfPermission(this,
                    == PackageManager.PERMISSION_GRANTED) {
                //Location Permission already granted
            } else {
                //Request Location Permission
        else {

    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)

    public void onConnected(Bundle bundle) {
        mLocationRequest = new LocationRequest();
        if (ContextCompat.checkSelfPermission(this,
                == PackageManager.PERMISSION_GRANTED) {
            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);

    public void onConnectionSuspended(int i) {}

    public void onConnectionFailed(ConnectionResult connectionResult) {}

    public void onLocationChanged(Location location)
        mLastLocation = location;
        if (mCurrLocationMarker != null) {

        //Place current location marker
        LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
        MarkerOptions markerOptions = new MarkerOptions();
        markerOptions.title("Current Position");
        mCurrLocationMarker = mGoogleMap.addMarker(markerOptions);

        //move map camera


    public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
    private void checkLocationPermission() {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
                != PackageManager.PERMISSION_GRANTED) {

            // Should we show an explanation?
            if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                    Manifest.permission.ACCESS_FINE_LOCATION)) {

                // Show an explanation to the user *asynchronously* -- don't block
                // this thread waiting for the user's response! After the user
                // sees the explanation, try again to request the permission.
                new AlertDialog.Builder(this)
                        .setTitle("Location Permission Needed")
                        .setMessage("This app needs the Location permission, please accept to use location functionality")
                        .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialogInterface, int i) {
                                //Prompt the user once explanation has been shown
                                        new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                                        MY_PERMISSIONS_REQUEST_LOCATION );

            } else {
                // No explanation needed, we can request the permission.
                        new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                        MY_PERMISSIONS_REQUEST_LOCATION );

    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[], int[] grantResults) {
        switch (requestCode) {
                // If request is cancelled, the result arrays are empty.
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                    // permission was granted, yay! Do the
                    // location-related task you need to do.
                    if (ContextCompat.checkSelfPermission(this,
                            == PackageManager.PERMISSION_GRANTED) {

                        if (mGoogleApiClient == null) {

                } else {

                    // permission denied, boo! Disable the
                    // functionality that depends on this permission.
                    Toast.makeText(this, "permission denied", Toast.LENGTH_LONG).show();

            // other 'case' lines to check for other
            // permissions this app might request



<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
    android:orientation="vertical" android:layout_width="match_parent"

    <fragment xmlns:android=""



Show permission explanation if needed using an AlertDialog (this happens if the user denies a permission request, or grants the permission and then later revokes it in the settings):

enter image description here

Prompt the user for Location permission by calling ActivityCompat.requestPermissions():

enter image description here

Move camera to current location and place Marker when the Location permission is granted:

enter image description here

How to add a recyclerView inside another recyclerView

I ran into similar problem a while back and what was happening in my case was the outer recycler view was working perfectly fine but the the adapter of inner/second recycler view had minor issues all the methods like constructor got initiated and even getCount() method was being called, although the final methods responsible to generate view ie..

1. onBindViewHolder() methods never got called. --> Problem 1.

2. When it got called finally it never show the list items/rows of recycler view. --> Problem 2.

Reason why this happened :: When you put a recycler view inside another recycler view, then height of the first/outer recycler view is not auto adjusted. It is defined when the first/outer view is created and then it remains fixed. At that point your second/inner recycler view has not yet loaded its items and thus its height is set as zero and never changes even when it gets data. Then when onBindViewHolder() in your second/inner recycler view is called, it gets items but it doesn't have the space to show them because its height is still zero. So the items in the second recycler view are never shown even when the onBindViewHolder() has added them to it.

Solution :: you have to create your custom LinearLayoutManager for the second recycler view and that is it. To create your own LinearLayoutManager: Create a Java class with the name CustomLinearLayoutManager and paste the code below into it. NO CHANGES REQUIRED

public class CustomLinearLayoutManager extends LinearLayoutManager {

    private static final String TAG = CustomLinearLayoutManager.class.getSimpleName();

    public CustomLinearLayoutManager(Context context) {


    public CustomLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);

    private int[] mMeasuredDimension = new int[2];

    public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, int widthSpec, int heightSpec) {

        final int widthMode = View.MeasureSpec.getMode(widthSpec);
        final int heightMode = View.MeasureSpec.getMode(heightSpec);
        final int widthSize = View.MeasureSpec.getSize(widthSpec);
        final int heightSize = View.MeasureSpec.getSize(heightSpec);

        int width = 0;
        int height = 0;
        for (int i = 0; i < getItemCount(); i++) {
            measureScrapChild(recycler, i, View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),

            if (getOrientation() == HORIZONTAL) {
                width = width + mMeasuredDimension[0];
                if (i == 0) {
                    height = mMeasuredDimension[1];
            } else {
                height = height + mMeasuredDimension[1];
                if (i == 0) {
                    width = mMeasuredDimension[0];
        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
                width = widthSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:

        switch (heightMode) {
            case View.MeasureSpec.EXACTLY:
                height = heightSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:

        setMeasuredDimension(width, height);

    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                                   int heightSpec, int[] measuredDimension) {
        try {
            View view = recycler.getViewForPosition(position);

            if (view != null) {
                RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();

                int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                        getPaddingLeft() + getPaddingRight(), p.width);

                int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                        getPaddingTop() + getPaddingBottom(), p.height);

                view.measure(childWidthSpec, childHeightSpec);
                measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
                measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
        } catch (Exception e) {

Angular2 - TypeScript : Increment a number after timeout in AppComponent

This is not valid TypeScript code. You can not have method invocations in the body of a class.

export class AppComponent {
  public n: number = 1;
  setTimeout(function() {
    n = n + 10;
  }, 1000);

Instead move the setTimeout call to the constructor of the class. Additionally, use the arrow function => to gain access to this.

export class AppComponent {
  public n: number = 1;

  constructor() {
    setTimeout(() => {
      this.n = this.n + 10;
    }, 1000);


In TypeScript, you can only refer to class properties or methods via this. That's why the arrow function => is important.

Why is my JQuery selector returning a n.fn.init[0], and what is it?

Error is that you are using 'ID' in lower case like 'checkbox1' but when you loop json object its return in upper case. So you need to replace checkbox1 to CHECKBOX1.

In my case :-

var response = jQuery.parseJSON(response);

$.each(response, function(key, value) {
   $.each(value, function(key, value){


  <input type="text" name="abc" id="abc" value="">

I am getting the same error but when i replace the id in html code its work fine.


<input type="text" name="abc" id="ABC" value="">

A connection was successfully established with the server, but then an error occurred during the login process. (Error Number: 233)

My problem resolved by this what changes i have done in .net core Do this changes in Appsetting.json

Server=***;Database=***;Persist Security Info=False;User ID=***; Password=***;MultipleActiveResultSets=False;Encrypt=False;TrustServerCertificate=False;Connection Timeout=30

and Do following changes in Package console manager

Scaffold-DbContext "Server=***;Database=***;Persist Security Info=False;User ID=***; Password=***;MultipleActiveResultSets=False;Encrypt=False;TrustServerCertificate=False;Connection Timeout=30;" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -Context DatabaseContext -f

Happy coding

Visual Studio Code always asking for git credentials

The following steps walk you through how to:

  1. Generate SSH keys (without passphrase**)
  2. Add the public key generated in step 1 to your Git repository
  3. Confirm the above steps have been completed successfully
  4. Make your first commit (without having to provide a username / password)

**Generating SSH keys without a passphrase is unwise if your work is particularly sensitive.

OS - Fedora 28 | Editor - VS Code v1.23.0 | Repository - Git

Generate SSH keys:

  • ssh-keygen -t rsa -C "[email protected]"
  • Enter file in which to save the key: Press Enter
  • Enter passphrase: Press Enter
  • Enter same passphrase again: Press Enter

After completing the above steps, the location of your public key is shown in the terminal window. If the currently logged in user is 'bob' the location of your public key would be /home/bob/.ssh/

Copy and import public key to GitHub:

  • cat /home/bob/.ssh/

  • Copy the whole public key that is now displayed in your terminal window to the clipboard

  • Go to and sign in
  • Click the user icon in the top right corner of the screen and select Settings
  • Click SSH and GPG keys
  • Click New SSH key
  • Enter a title, paste the public key copied to the clipboard in the first bullet point, and click Add SSH key

Confirm the above steps:

  • ssh -T [email protected]

  • yes

  • Hi ! You've successfully authenticated, but GitHub does not provide shell access.

First commit / push without having to enter a username / password: - touch test.txt

  • git add test.txt

  • git commit - opens editor, enter a message and save the file. If vi is your editor, press i once the file opens, enter a message, press esc, and then enter :x to save changes.

  • git push

The only hiccup you may encounter is when you attempt to SSH to GitHub. This link will provide some assistance -

Happy hunting!

Spring Boot @autowired does not work, classes in different package

For this kind of issue, I ended up in putting @Service annotation on the newly created service class then the autowire was picked up. So, try to check those classes which are not getting autowired, if they need the corresponding required annotations(like @Controller, @Service, etc.) applied to them and then try to build the project again.

android : Error converting byte to dex

Check you build.gradle (Module: your app).

All libraries must use the exact same version specification (mixing versions can lead to runtime crashes).

For example: If you have and

You have to change the firebase version to: 10.0.1

How to resolve the "EVP_DecryptFInal_ex: bad decrypt" during file decryption

This message can also occur when you specify the incorrect decryption password (yeah, lame, but not quite obvious to realize this from the error message, huh?).

I was using the command line to decrypt the recent DataBase backup for my auxiliary tool and suddenly faced this issue.

Finally, after 10 mins of grief and plus reading through this question/answers I have remembered that the password is different and everything worked just fine with the correct password.

AWS : The config profile (MyName) could not be found

can you check your config file under ~/.aws/config- you might have an invalid section called [myname], something like this (this is an example)



Just remove the [myname] section (including all content for this profile) and you will be fine to run aws cli again

How to increase Bootstrap Modal Width?

In Bootstrap, the default width of modal-dialog is 600px. But you can explicitly change its width. For instance, if you would like to maximize its width to the value of your choice, 800px for instance, you do as following:

.modal-dialog {
    width: 800px;
    margin: 30px auto;

Note: This change sets to all modal dialog you use in your application. Also, my suggestion is it is best to have your own CSS rules defined and not to touch the core of the framework.

If you only want it to be set for specific modal dialog, use your own catchy class name as modal-800 whose width is set to 800px, as following:


<div class="modal">
   <div class="modal-dialog modal-800">
      <div class="modal-content">



.modal-dialog.modal-800 {
    width: 800px;
    margin: 30px auto;

Likewise, you can have class name as based on the width size like modal-700 whose width is 700px.

Hope it's helpful!

Convert bytes to int?

int.from_bytes( bytes, byteorder, *, signed=False )

doesn't work with me I used function from this website, it works well

def bytes_to_int(bytes):
    result = 0
    for b in bytes:
        result = result * 256 + int(b)
    return result

def int_to_bytes(value, length):
    result = []
    for i in range(0, length):
        result.append(value >> (i * 8) & 0xff)
    return result

Python: How to increase/reduce the fontsize of x and y tick labels?

It is simpler than I thought it would be.

To set the font size of the x-axis ticks:

x_ticks=['x tick 1','x tick 2','x tick 3']
ax.set_xticklabels(x_ticks, rotation=0, fontsize=8)

To do it for the y-axis ticks:

y_ticks=['y tick 1','y tick 2','y tick 3']
ax.set_yticklabels(y_ticks, rotation=0, fontsize=8)

The arguments rotation and fontsize can easily control what I was after.


Failed to authenticate on SMTP server error using gmail

Did you turn on the "Allow less secure apps" on? go to this link

Take a look at the Sign-in & security -> Apps with account access menu.

You must turn the option "Allow less secure apps" ON.

If is still doesn't work try one of these:

And change your .env file

[email protected]

because the one's you have specified in the mail.php will only be used if the value is not available in the .env file.

How to select the first row of each group?

Window functions:

Something like this should do the trick:

import org.apache.spark.sql.functions.{row_number, max, broadcast}
import org.apache.spark.sql.expressions.Window

val df = sc.parallelize(Seq(
  (0,"cat26",30.9), (0,"cat13",22.1), (0,"cat95",19.6), (0,"cat105",1.3),
  (1,"cat67",28.5), (1,"cat4",26.8), (1,"cat13",12.6), (1,"cat23",5.3),
  (2,"cat56",39.6), (2,"cat40",29.7), (2,"cat187",27.9), (2,"cat68",9.8),
  (3,"cat8",35.6))).toDF("Hour", "Category", "TotalValue")

val w = Window.partitionBy($"hour").orderBy($"TotalValue".desc)

val dfTop = df.withColumn("rn", row_number.over(w)).where($"rn" === 1).drop("rn")
// +----+--------+----------+
// |Hour|Category|TotalValue|
// +----+--------+----------+
// |   0|   cat26|      30.9|
// |   1|   cat67|      28.5|
// |   2|   cat56|      39.6|
// |   3|    cat8|      35.6|
// +----+--------+----------+

This method will be inefficient in case of significant data skew.

Plain SQL aggregation followed by join:

Alternatively you can join with aggregated data frame:

val dfMax = df.groupBy($"hour".as("max_hour")).agg(max($"TotalValue").as("max_value"))

val dfTopByJoin = df.join(broadcast(dfMax),
    ($"hour" === $"max_hour") && ($"TotalValue" === $"max_value"))

// +----+--------+----------+
// |Hour|Category|TotalValue|
// +----+--------+----------+
// |   0|   cat26|      30.9|
// |   1|   cat67|      28.5|
// |   2|   cat56|      39.6|
// |   3|    cat8|      35.6|
// +----+--------+----------+

It will keep duplicate values (if there is more than one category per hour with the same total value). You can remove these as follows:


Using ordering over structs:

Neat, although not very well tested, trick which doesn't require joins or window functions:

val dfTop =$"Hour", struct($"TotalValue", $"Category").alias("vs"))
  .select($"Hour", $"vs.Category", $"vs.TotalValue")
// +----+--------+----------+
// |Hour|Category|TotalValue|
// +----+--------+----------+
// |   0|   cat26|      30.9|
// |   1|   cat67|      28.5|
// |   2|   cat56|      39.6|
// |   3|    cat8|      35.6|
// +----+--------+----------+

With DataSet API (Spark 1.6+, 2.0+):

Spark 1.6:

case class Record(Hour: Integer, Category: String, TotalValue: Double)[Record]
  .reduce((x, y) => if (x.TotalValue > y.TotalValue) x else y)

// +---+--------------+
// | _1|            _2|
// +---+--------------+
// |[0]|[0,cat26,30.9]|
// |[1]|[1,cat67,28.5]|
// |[2]|[2,cat56,39.6]|
// |[3]| [3,cat8,35.6]|
// +---+--------------+

Spark 2.0 or later:[Record]
  .reduceGroups((x, y) => if (x.TotalValue > y.TotalValue) x else y)

The last two methods can leverage map side combine and don't require full shuffle so most of the time should exhibit a better performance compared to window functions and joins. These cane be also used with Structured Streaming in completed output mode.

Don't use:

df.orderBy(...).groupBy(...).agg(first(...), ...)

It may seem to work (especially in the local mode) but it is unreliable (see SPARK-16207, credits to Tzach Zohar for linking relevant JIRA issue, and SPARK-30335).

The same note applies to


which internally uses equivalent execution plan.

How to use refs in React with Typescript

Lacking a complete example, here is my little test script for getting user input when working with React and TypeScript. Based partially on the other comments and this link

/// <reference path="typings/react/react-global.d.ts" />

// Init our code using jquery on document ready
$(function () {
    ReactDOM.render(<ServerTime />, document.getElementById("reactTest"));

interface IServerTimeProps {

interface IServerTimeState {
    time: string;

interface IServerTimeInputs {
    userFormat?: HTMLInputElement;

class ServerTime extends React.Component<IServerTimeProps, IServerTimeState> {
    inputs: IServerTimeInputs = {};

    constructor() {
        this.state = { time: "unknown" }

    render() {
        return (
                <div>Server time: { this.state.time }</div>
                <input type="text" ref={ a => this.inputs.userFormat = a } defaultValue="s" ></input>
                <button onClick={ this._buttonClick.bind(this) }>GetTime</button>

    // Update state with value from server
    _buttonClick(): void {

        // This part requires a listening web server to work, but alert shows the user input
        method: "POST",
        data: { format: this.inputs.userFormat.value },
        url: "/Home/ServerTime",
        success: (result) => {
            this.setState({ time : result });


RecyclerView - Get view at particular position

You can use use both

recyclerViewInstance.findViewHolderForAdapterPosition(adapterPosition) and recyclerViewInstance.findViewHolderForLayoutPosition(layoutPosition). Be sure that RecyclerView view uses two type of positions

Adapter position : Position of an item in the adapter. This is the position from the Adapter's perspective. Layout position : Position of an item in the latest layout calculation. This is the position from the LayoutManager's perspective. You should use getAdapterPosition() for findViewHolderForAdapterPosition(adapterPosition) and getLayoutPosition() for findViewHolderForLayoutPosition(layoutPosition).

Take a member variable to hold previously selected item position in recyclerview adapter and other member variable to check whether user is clicking for first time or not.

Sample code and screen shots are attached for more information at the bottom.

public class MainActivity extends AppCompatActivity {     

private RecyclerView mRecyclerList = null;    
private RecyclerAdapter adapter = null;    

protected void onCreate(Bundle savedInstanceState) {    

    mRecyclerList = (RecyclerView) findViewById(;    

protected void onStart() {    
    RecyclerView.LayoutManager layoutManager = null;    
    String[] daysArray = new String[15];    
    String[] datesArray = new String[15];    

    for (int i = 0; i < daysArray.length; i++){    
        daysArray[i] = "Sunday";    
        datesArray[i] = "12 Feb 2017";    

    adapter = new RecyclerAdapter(mRecyclerList, daysArray, datesArray);    
    layoutManager = new LinearLayoutManager(MainActivity.this);    

public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.MyCardViewHolder>{          

private final String TAG = "RecyclerAdapter";        
private Context mContext = null;        
private TextView mDaysTxt = null, mDateTxt = null;    
private LinearLayout mDateContainerLayout = null;    
private String[] daysArray = null, datesArray = null;    
private RecyclerView mRecyclerList = null;    
private int previousPosition = 0;    
private boolean flagFirstItemSelected = false;    

public RecyclerAdapter(RecyclerView mRecyclerList, String[] daysArray, String[] datesArray){    
    this.mRecyclerList = mRecyclerList;    
    this.daysArray = daysArray;    
    this.datesArray = datesArray;    

public MyCardViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {    
    LayoutInflater layoutInflater = null;    
    View view = null;    
    MyCardViewHolder cardViewHolder = null;    
    mContext = parent.getContext();    
    layoutInflater = LayoutInflater.from(mContext);    
    view = layoutInflater.inflate(R.layout.date_card_row, parent, false);    
    cardViewHolder = new MyCardViewHolder(view);    
    return cardViewHolder;    

public void onBindViewHolder(MyCardViewHolder holder, final int position) {    
    mDaysTxt = holder.mDaysTxt;    
    mDateTxt = holder.mDateTxt;    
    mDateContainerLayout = holder.mDateContainerLayout;    


    if (!flagFirstItemSelected){    
        flagFirstItemSelected = true;    
    }else {    

public int getItemCount() {    
    return daysArray.length;    

class MyCardViewHolder extends RecyclerView.ViewHolder{    
    TextView mDaysTxt = null, mDateTxt = null;    
    LinearLayout mDateContainerLayout = null;    
    LinearLayout linearLayout = null;    
    View view = null;    
    MyCardViewHolder myCardViewHolder = null;    

    public MyCardViewHolder(View itemView) {    
        mDaysTxt = (TextView) itemView.findViewById(;    
        mDateTxt = (TextView) itemView.findViewById(;    
        mDateContainerLayout = (LinearLayout) itemView.findViewById(;    

        mDateContainerLayout.setOnClickListener(new View.OnClickListener() {    
            public void onClick(View v) {    
                LinearLayout linearLayout = null;    
                View view = null;    

                if (getAdapterPosition() == previousPosition){    
                    view = mRecyclerList.findViewHolderForAdapterPosition(previousPosition).itemView;    
                    linearLayout = (LinearLayout) view.findViewById(;    
                    previousPosition = getAdapterPosition();    

                }else {    
                    view = mRecyclerList.findViewHolderForAdapterPosition(previousPosition).itemView;    
                    linearLayout = (LinearLayout) view.findViewById(;    

                    view = mRecyclerList.findViewHolderForAdapterPosition(getAdapterPosition()).itemView;    
                    linearLayout = (LinearLayout) view.findViewById(;    
                    previousPosition = getAdapterPosition();    

} first element selected second element selected and previously selected item becomes unselected fifth element selected and previously selected item becomes unselected

Spring Boot - How to log all requests and responses with exceptions in single place?

I had defined logging level in to print requests/responses, method url in the log file

I had used Spring Boot.

How to convert string to integer in PowerShell


2.032 MB (2,131,022 bytes)


$u=$u.trimend(" bytes)") #yields 2.032 MB (2,131,022

$u=$u.Split("(") #yields `$u[1]` as 2,131,022


The result is 2131022 in integer form.

Call a Vue.js component method from outside the component

Here is a simple one


In android how to set navigation drawer header image and name programmatically in class file?

Here is my code below perfectly working Do not add the header in NavigationView tag in activity_main.xml

    android:layout_height="match_parent" />

    app:itemBackground="@drawable/active_drawer_color" />

add header programmatically with below code

View navHeaderView = navigationView.inflateHeaderView(R.layout.nav_header_main);
    headerUserName = (TextView) navHeaderView.findViewById(;
    headerMobileNo = (TextView) navHeaderView.findViewById(;
    headerUserName.setText("Anirudh R Huilgol");

REST API - file (ie images) processing - best practices

There's no easy solution. Each way has their pros and cons . But the canonical way is using the first option: multipart/form-data. As W3 recommendation guide says

The content type "multipart/form-data" should be used for submitting forms that contain files, non-ASCII data, and binary data.

We aren't sending forms,really, but the implicit principle still applies. Using base64 as a binary representation, is incorrect because you're using the incorrect tool for accomplish your goal, in other hand, the second option forces your API clients to do more job in order to consume your API service. You should do the hard work in the server side in order to supply an easy-to-consume API. The first option is not easy to debug, but when you do it, it probably never changes.

Using multipart/form-data you're sticked with the REST/http philosophy. You can view an answer to similar question here.

Another option if mixing the alternatives, you can use multipart/form-data but instead of send every value separate, you can send a value named payload with the json payload inside it. (I tried this approach using ASP.NET WebAPI 2 and works fine).

Get JSON Data from URL Using Android?

Here in this snippet, we will see a volley method, add below dependency in-app level gradle file

  1. compile '' -> adding volley dependency.
  2. implementation '' -> adding gson for JSON data manipulation in android.

Dummy URL -> (HTTP GET Method Request)

public void getdata(){
    Response.Listener<String> response_listener = new Response.Listener<String>() {
        public void onResponse(String response) {
            try {
                JSONArray jsonArray = new JSONArray(response);
                JSONObject jsonObject = jsonArray.getJSONObject(0).getJSONObject("address").getJSONObject("geo");
            } catch (JSONException e) {

    Response.ErrorListener response_error_listener = new Response.ErrorListener() {
        public void onErrorResponse(VolleyError error) {
            if (error instanceof TimeoutError || error instanceof NoConnectionError) {
            } else if (error instanceof AuthFailureError) {
            } else if (error instanceof ServerError) {
            } else if (error instanceof NetworkError) {
            } else if (error instanceof ParseError) {

    StringRequest stringRequest = new StringRequest(Request.Method.GET, "",response_listener,response_error_listener);

public RequestQueue getRequestQueue() {
    //requestQueue is used to stack your request and handles your cache.
    if (mRequestQueue == null) {
        mRequestQueue = Volley.newRequestQueue(getApplicationContext());
    return mRequestQueue;


Convert time.Time to string

Go Playground

package main

import (

func main() {
    t := time.Now()
    // The Time type implements the Stringer interface -- it
    // has a String() method which gets called automatically by
    // functions like Printf().
    fmt.Printf("%s\n", t)

    // See the Constants section for more formats
    formatedTime := t.Format(time.RFC1123)

Could not create SSL/TLS secure channel, despite setting ServerCertificateValidationCallback

move this line: ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;

Before this line: HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

Original post: KB4344167 security update breaks TLS Code

Hibernate-sequence doesn't exist

in hibernate 5.x, you should add set to false in hibernate.cfg.xml

    <property name="show_sql">1</property>
    <property name="">false</property>

Laravel migration table field's type change

2018 Solution, still other answers are valid but you dont need to use any dependency:

First you have to create a new migration:

php artisan make:migration change_appointment_time_column_type

Then in that migration file up(), try:

    Schema::table('appointments', function ($table) {

If you donot change the size default will be varchar(191) but If you want to change size of the field:

    Schema::table('appointments', function ($table) {
        $table->string('time', 40)->change();

Then migrate the file by:

php artisan migrate

more info from doc.

How can I increase the size of a bootstrap button?

Default Bootstrap size classes

You can use btn-lg, btn-sm and btn-xs classes for manipulating with its size.


Also, there is a class btn-block which will extend your button to the whole block. It is very convenient in combination with Bootstrap grid.
For example, this code will show a button with the width equal to half of screen for medium and large screens; and will show a full-width button for small screens:

<div class="container">
    <div class="col-xs-12 col-xs-offset-0 col-sm-offset-3 col-sm-6">
        <button class="btn btn-group">Click me!</button>

Check this JSFiddle out. Try to resize frame.

If it is not enough, you can easily create your custom class.

How to decrypt Hash Password in Laravel

For compare hashed password with the plain text password string you can use the PHP password_verify

if(password_verify('1234567', $crypt_password_string)) {
    // in case if "$crypt_password_string" actually hides "1234567"

Expected response code 220 but got code "", with message "" in Laravel

For me the problem was the port. I first incorrectly used port 465, which works for SSL but not TLS. So the key thing was changing the port to 587.

Cannot resolve symbol HttpGet,HttpClient,HttpResponce in Android Studio

Please remove all jar files of Http from libs folder and add below dependencies in gradle file :

compile 'org.apache.httpcomponents:httpclient:4.5'
compile 'org.apache.httpcomponents:httpcore:4.4.3'


How to to send mail using gmail in Laravel?

All you have to do is just edit in you.env file, that's it.


for app password goto

and genearate your app pasword and save for future use. because once you generate app password you cannot re-edit password or change same app password.(you can create multiple app password)

Explain ggplot2 warning: "Removed k rows containing missing values"

Just for the shake of completing the answer given by eipi10.

I was facing the same problem, without using scale_y_continuous nor coord_cartesian.

The conflict was coming from the x axis, where I defined limits = c(1, 30). It seems such limits do not provide enough space if you want to "dodge" your bars, so R still throws the error

Removed 8 rows containing missing values (geom_bar)

Adjusting the limits of the x axis to limits = c(0, 31) solved the problem.

In conclusion, even if you are not putting limits to your y axis, check out your x axis' behavior to ensure you have enough space

Resolving instances with ASP.NET Core DI from within ConfigureServices

The IServiceCollection interface is used for building a dependency injection container. After it's fully built, it gets composed to an IServiceProvider instance which you can use to resolve services. You can inject an IServiceProvider into any class. The IApplicationBuilder and HttpContext classes can provide the service provider as well, via their ApplicationServices or RequestServices properties respectively.

IServiceProvider defines a GetService(Type type) method to resolve a service:

var service = (IFooService)serviceProvider.GetService(typeof(IFooService));

There are also several convenience extension methods available, such as serviceProvider.GetService<IFooService>() (add a using for Microsoft.Extensions.DependencyInjection).

Resolving services inside the startup class

Injecting dependencies

The runtime's hosting service provider can inject certain services into the constructor of the Startup class, such as IConfiguration, IWebHostEnvironment (IHostingEnvironment in pre-3.0 versions), ILoggerFactory and IServiceProvider. Note that the latter is an instance built by the hosting layer and contains only the essential services for starting up an application.

The ConfigureServices() method does not allow injecting services, it only accepts an IServiceCollection argument. This makes sense because ConfigureServices() is where you register the services required by your application. However you can use services injected in the startup's constructor here, for example:

public Startup(IConfiguration configuration)
    Configuration = configuration;

public IConfiguration Configuration { get; }

public void ConfigureServices(IServiceCollection services)
    // Use Configuration here

Any services registered in ConfigureServices() can then be injected into the Configure() method; you can add an arbitrary number of services after the IApplicationBuilder parameter:

public void ConfigureServices(IServiceCollection services)

public void Configure(IApplicationBuilder app, IFooService fooService)

Manually resolving dependencies

If you need to manually resolve services, you should preferably use the ApplicationServices provided by IApplicationBuilder in the Configure() method:

public void Configure(IApplicationBuilder app)
    var serviceProvider = app.ApplicationServices;
    var hostingEnv = serviceProvider.GetService<IHostingEnvironment>();

It is possible to pass and directly use an IServiceProvider in the constructor of your Startup class, but as above this will contain a limited subset of services, and thus has limited utility:

public Startup(IServiceProvider serviceProvider)
    var hostingEnv = serviceProvider.GetService<IWebHostEnvironment>();

If you must resolve services in the ConfigureServices() method, a different approach is required. You can build an intermediate IServiceProvider from the IServiceCollection instance which contains the services which have been registered up to that point:

public void ConfigureServices(IServiceCollection services)
    services.AddSingleton<IFooService, FooService>();

    // Build the intermediate service provider
    var sp = services.BuildServiceProvider();

    // This will succeed.
    var fooService = sp.GetService<IFooService>();
    // This will fail (return null), as IBarService hasn't been registered yet.
    var barService = sp.GetService<IBarService>();

Please note: Generally you should avoid resolving services inside the ConfigureServices() method, as this is actually the place where you're configuring the application services. Sometimes you just need access to an IOptions<MyOptions> instance. You can accomplish this by binding the values from the IConfiguration instance to an instance of MyOptions (which is essentially what the options framework does):

public void ConfigureServices(IServiceCollection services)
    var myOptions = new MyOptions();

Manually resolving services (aka Service Locator) is generally considered an anti-pattern. While it has its use-cases (for frameworks and/or infrastructure layers), you should avoid it as much as possible.

How to get a context in a recycler view adapter

You can define:

Context ctx; 

And on onCreate initialise ctx to:


Note: Parent is a ViewGroup.

Android "gps requires ACCESS_FINE_LOCATION" error, even though my manifest file contains this

ACCESS_COARSE_LOCATION, ACCESS_FINE_LOCATION, and WRITE_EXTERNAL_STORAGE are all part of the Android 6.0 runtime permission system. In addition to having them in the manifest as you do, you also have to request them from the user at runtime (using requestPermissions()) and see if you have them (using checkSelfPermission()).

One workaround in the short term is to drop your targetSdkVersion below 23.

But, eventually, you will want to update your app to use the runtime permission system.

For example, this activity works with five permissions. Four are runtime permissions, though it is presently only handling three (I wrote it before WRITE_EXTERNAL_STORAGE was added to the runtime permission roster).

 Copyright (c) 2015 CommonsWare, LLC
 Licensed under the Apache License, Version 2.0 (the "License"); you may not
 use this file except in compliance with the License. You may obtain a copy
 of the License at Unless required
 by applicable law or agreed to in writing, software distributed under the
 OF ANY KIND, either express or implied. See the License for the specific
 language governing permissions and limitations under the License.

 From _The Busy Coder's Guide to Android Development_


import android.Manifest;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
  private static final String[] INITIAL_PERMS={
  private static final String[] CAMERA_PERMS={
  private static final String[] CONTACTS_PERMS={
  private static final String[] LOCATION_PERMS={
  private static final int INITIAL_REQUEST=1337;
  private static final int CAMERA_REQUEST=INITIAL_REQUEST+1;
  private static final int CONTACTS_REQUEST=INITIAL_REQUEST+2;
  private static final int LOCATION_REQUEST=INITIAL_REQUEST+3;
  private TextView location;
  private TextView camera;
  private TextView internet;
  private TextView contacts;
  private TextView storage;

  protected void onCreate(Bundle savedInstanceState) {


    if (!canAccessLocation() || !canAccessContacts()) {
      requestPermissions(INITIAL_PERMS, INITIAL_REQUEST);

  protected void onResume() {


  public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(, menu);


  public boolean onOptionsItemSelected(MenuItem item) {
    switch(item.getItemId()) {
        if (canAccessCamera()) {
        else {
          requestPermissions(CAMERA_PERMS, CAMERA_REQUEST);

        if (canAccessContacts()) {
        else {
          requestPermissions(CONTACTS_PERMS, CONTACTS_REQUEST);

        if (canAccessLocation()) {
        else {
          requestPermissions(LOCATION_PERMS, LOCATION_REQUEST);


  public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {

    switch(requestCode) {
      case CAMERA_REQUEST:
        if (canAccessCamera()) {
        else {

        if (canAccessContacts()) {
        else {

        if (canAccessLocation()) {
        else {

  private void updateTable() {

  private boolean canAccessLocation() {

  private boolean canAccessCamera() {

  private boolean canAccessContacts() {

  private boolean hasPermission(String perm) {

  private void bzzzt() {
    Toast.makeText(this, R.string.toast_bzzzt, Toast.LENGTH_LONG).show();

  private void doCameraThing() {
    Toast.makeText(this, R.string.toast_camera, Toast.LENGTH_SHORT).show();

  private void doContactsThing() {
    Toast.makeText(this, R.string.toast_contacts, Toast.LENGTH_SHORT).show();

  private void doLocationThing() {
    Toast.makeText(this, R.string.toast_location, Toast.LENGTH_SHORT).show();

(from this sample project)

For the requestPermissions() function, should the parameters just be "ACCESS_COARSE_LOCATION"? Or should I include the full name "android.permission.ACCESS_COARSE_LOCATION"?

I would use the constants defined on Manifest.permission, as shown above.

Also, what is the request code?

That will be passed back to you as the first parameter to onRequestPermissionsResult(), so you can tell one requestPermissions() call from another.

Changing text color of menu item in navigation drawer

To change the individual text color of a single item, use a SpannableString like below:

NavigationView navDrawer;
Menu menu = navDrawer.getMenu();

SpannableString spannableString = new SpannableString("Menu item"));
        spannableString.setSpan(new ForegroundColorSpan(getResources().getColor(R.color.colorPrimary)), 0, spannableString.length(), 0);


RecyclerView and java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter positionViewHolder in Samsung devices

I faced this issue once, and I solved this by wrapping the LayoutManager and disabling predictive animations.

Here an example:

public class LinearLayoutManagerWrapper extends LinearLayoutManager {

  public LinearLayoutManagerWrapper(Context context) {

  public LinearLayoutManagerWrapper(Context context, int orientation, boolean reverseLayout) {
    super(context, orientation, reverseLayout);

  public LinearLayoutManagerWrapper(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
    super(context, attrs, defStyleAttr, defStyleRes);

  public boolean supportsPredictiveItemAnimations() {
    return false;

And set it to RecyclerView:

RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManagerWrapper(context, LinearLayoutManager.VERTICAL, false);

How do I change a tab background color when using TabLayout?

Have you tried checking the API?

You will need to create a listener for the OnTabSelectedListener event, then when a user selects any tab you should check if it is the correct one, then change the background color using tabLayout.setBackgroundColor(int color), or if it is not the correct tab make sure you change back to the normal color again with the same method.

Spark - repartition() vs coalesce()

All the answers are adding some great knowledge into this very often asked question.

So going by tradition of this question's timeline, here are my 2 cents.

I found the repartition to be faster than coalesce, in very specific case.

In my application when the number of files that we estimate is lower than the certain threshold, repartition works faster.

Here is what I mean

if(numFiles > 20)

In above snippet, if my files were less than 20, coalesce was taking forever to finish while repartition was much faster and so the above code.

Of course, this number (20) will depend on the number of workers and amount of data.

Hope that helps.

How to update RecyclerView Adapter Data?

you have 2 options to do this: refresh UI from the adapter:


or refresh it from recyclerView itself:


Lazy Loading vs Eager Loading

Eager Loading: Eager Loading helps you to load all your needed entities at once. i.e. related objects (child objects) are loaded automatically with its parent object.

When to use:

  1. Use Eager Loading when the relations are not too much. Thus, Eager Loading is a good practice to reduce further queries on the Server.
  2. Use Eager Loading when you are sure that you will be using related entities with the main entity everywhere.

Lazy Loading: In case of lazy loading, related objects (child objects) are not loaded automatically with its parent object until they are requested. By default LINQ supports lazy loading.

When to use:

  1. Use Lazy Loading when you are using one-to-many collections.
  2. Use Lazy Loading when you are sure that you are not using related entities instantly.

NOTE: Entity Framework supports three ways to load related data - eager loading, lazy loading and explicit loading.

How to decode encrypted wordpress admin password?

MD5 encrypting is possible, but decrypting is still unknown (to me). However, there are many ways to compare these things.

  1. Using compare methods like so:

      $db_pass = $P$BX5675uhhghfhgfhfhfgftut/0;
      $my_pass = "mypass";
      if ($db_pass === md5($my_pass)) {
        // password is matched
      } else {
        // password didn't match
  2. Only for WordPress users. If you have access to your PHPMyAdmin, focus you have because you paste that hashing here: $P$BX5675uhhghfhgfhfhfgftut/0, WordPress user_pass is not only MD5 format it also uses utf8_mb4_cli charset so what to do?

    That's why I use another Approach if I forget my WordPress password I use

    I install other WordPress with new password :P, and I then go to PHPMyAdmin and copy that hashing from the database and paste that hashing to my current PHPMyAdmin password ( which I forget )

    EASY is use this :

    1. password = "ARJUNsingh@123"
    2. password_hasing = " $P$BDSdKx2nglM.5UErwjQGeVtVWvjEvD1 "
    3. Replace your $P$BX5675uhhghfhgfhfhfgftut/0 with my $P$BDSdKx2nglM.5UErwjQGeVtVWvjEvD1



Navigation drawer: How do I set the selected item at startup?

For some reason it's preferable to find the MenuItem using the ID's.


Not an enclosing class error Android Studio

It should be

Intent myIntent = new Intent(this, Katra_home.class);

You have to use existing activity context to start new activity, new activity is not created yet, and you cannot use its context or call methods upon it.

not an enclosing class error is thrown because of your usage of this keyword. this is a reference to the current object — the object whose method or constructor is being called. With this you can only refer to any member of the current object from within an instance method or a constructor.

Katra_home.this is invalid construct

How to increase the max connections in postgres?

Just increasing max_connections is bad idea. You need to increase shared_buffers and kernel.shmmax as well.


max_connections determines the maximum number of concurrent connections to the database server. The default is typically 100 connections.

Before increasing your connection count you might need to scale up your deployment. But before that, you should consider whether you really need an increased connection limit.

Each PostgreSQL connection consumes RAM for managing the connection or the client using it. The more connections you have, the more RAM you will be using that could instead be used to run the database.

A well-written app typically doesn't need a large number of connections. If you have an app that does need a large number of connections then consider using a tool such as pg_bouncer which can pool connections for you. As each connection consumes RAM, you should be looking to minimize their use.

How to increase max connections

1. Increase max_connection and shared_buffers

in /var/lib/pgsql/{version_number}/data/postgresql.conf


max_connections = 100
shared_buffers = 24MB


max_connections = 300
shared_buffers = 80MB

The shared_buffers configuration parameter determines how much memory is dedicated to PostgreSQL to use for caching data.

  • If you have a system with 1GB or more of RAM, a reasonable starting value for shared_buffers is 1/4 of the memory in your system.
  • it's unlikely you'll find using more than 40% of RAM to work better than a smaller amount (like 25%)
  • Be aware that if your system or PostgreSQL build is 32-bit, it might not be practical to set shared_buffers above 2 ~ 2.5GB.
  • Note that on Windows, large values for shared_buffers aren't as effective, and you may find better results keeping it relatively low and using the OS cache more instead. On Windows the useful range is 64MB to 512MB.

2. Change kernel.shmmax

You would need to increase kernel max segment size to be slightly larger than the shared_buffers.

In file /etc/sysctl.conf set the parameter as shown below. It will take effect when postgresql reboots (The following line makes the kernel max to 96Mb)



Postgres Max Connections And Shared Buffers

Tuning Your PostgreSQL Server

Remove "Using default security password" on Spring Boot

On spring boot 2 with webflux you need to define a ReactiveAuthenticationManager

Docker error : no space left on device

you can also use:

docker system prune

or for just volumes:

docker volume prune

Android TabLayout Android Design

I try to solve here is my code.

first add dependency in build.gradle(app).

dependencies {
    compile ''

Create PagerAdapter.class

public class PagerAdapter extends FragmentPagerAdapter {

    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public PagerAdapter(FragmentManager manager) {

    public Fragment getItem(int position) {
        return mFragmentList.get(position);

    public int getCount() {
        return mFragmentList.size();

    public void addFragment(Fragment fragment, String title) {

    public CharSequence getPageTitle(int position) {

        return mFragmentTitleList.get(position);

create activity_main.xml

<RelativeLayout xmlns:android=""

        app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />

        android:layout_below="@id/tab_layout" />


create MainActivity.class

public class MainActivity extends AppCompatActivity {

    Pager pager;
    protected void onCreate(Bundle savedInstanceState) {
        Toolbar toolbar = (Toolbar) findViewById(;

        TabLayout tabLayout = (TabLayout) findViewById(;

        final ViewPager viewPager = (ViewPager) findViewById(;
         pager = new Pager(getSupportFragmentManager());

        pager.addFragment(new FragmentOne(), "One");



        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

        tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            public void onTabSelected(TabLayout.Tab tab) {

            public void onTabUnselected(TabLayout.Tab tab) {


            public void onTabReselected(TabLayout.Tab tab) {


and finally create fragment to add in viewpager

crate fragment_one.xml

<LinearLayout xmlns:android=""

        android:layout_height="wrap_content" />


Create FragmentOne.class

public class FragmentOne extends Fragment {

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_one, container,false);
        return view;

Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference

 mAddTaskButton.setOnClickListener(new View.OnClickListener()

you have a click listner but you haven't initialized the mAddTaskButton with your layout binding

Artisan, creating tables in database

in laravel 5 first we need to create migration and then run the migration

Step 1.

php artisan make:migration create_users_table --create=users

Step 2.

php artisan migrate

How to filter a RecyclerView with a SearchView

In Adapter:

public void setFilter(List<Channel> newList){
        mChannels = new ArrayList<>();

In Activity:

searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            public boolean onQueryTextSubmit(String query) {
                return false;

            public boolean onQueryTextChange(String newText) {
                newText = newText.toLowerCase();
                ArrayList<Channel> newList = new ArrayList<>();
                for (Channel channel: channels){
                    String channelName = channel.getmChannelName().toLowerCase();
                    if (channelName.contains(newText)){
                return true;

state provider and route provider in angularJS

You shouldn't use both ngRoute and UI-router. Here's a sample code for UI-router:

repoApp.config(function($stateProvider, $urlRouterProvider) {_x000D_
    .state('state1', {_x000D_
      url: "/state1",_x000D_
      templateUrl: "partials/state1.html",_x000D_
      controller: 'YourCtrl'_x000D_
    .state('state2', {_x000D_
      url: "/state2",_x000D_
      templateUrl: "partials/state2.html",_x000D_
      controller: 'YourOtherCtrl'_x000D_

You can find a great answer on the difference between these two in this thread: What is the difference between angular-route and angular-ui-router?

You can also consult UI-Router's docs here:

How to disable spring security for particular url

<http pattern="/resources/**" security="none"/>

Or with Java configuration:


Instead of the old:

 <intercept-url pattern="/resources/**" filters="none"/>

for exp . disable security for a login page :

  <intercept-url pattern="/login*" filters="none" />

RSA encryption and decryption in Python

# coding: utf-8
from __future__ import unicode_literals
import base64
import os

import six
from Crypto import Random
from Crypto.PublicKey import RSA

class PublicKeyFileExists(Exception): pass

class RSAEncryption(object):

    def encrypt(self, message):
        public_key = self._get_public_key()
        public_key_object = RSA.importKey(public_key)
        random_phrase = 'M'
        encrypted_message = public_key_object.encrypt(self._to_format_for_encrypt(message), random_phrase)[0]
        # use base64 for save encrypted_message in database without problems with encoding
        return base64.b64encode(encrypted_message)

    def decrypt(self, encoded_encrypted_message):
        encrypted_message = base64.b64decode(encoded_encrypted_message)
        private_key = self._get_private_key()
        private_key_object = RSA.importKey(private_key)
        decrypted_message = private_key_object.decrypt(encrypted_message)
        return six.text_type(decrypted_message, encoding='utf8')

    def generate_keys(self):
        """Be careful rewrite your keys"""
        random_generator =
        key = RSA.generate(1024, random_generator)
        private, public = key.exportKey(), key.publickey().exportKey()

        if os.path.isfile(self.PUBLIC_KEY_FILE_PATH):
            raise PublicKeyFileExists('???? ? ????????? ?????? ??????????. ??????? ????')

        with open(self.PRIVATE_KEY_FILE_PATH, 'w') as private_file:
        with open(self.PUBLIC_KEY_FILE_PATH, 'w') as public_file:
        return private, public

    def create_directories(self, for_private_key=True):
        public_key_path = self.PUBLIC_KEY_FILE_PATH.rsplit('/', 1)
        if not os.path.exists(public_key_path):
        if for_private_key:
            private_key_path = self.PRIVATE_KEY_FILE_PATH.rsplit('/', 1)
            if not os.path.exists(private_key_path):

    def _get_public_key(self):
        """run generate_keys() before get keys """
        with open(self.PUBLIC_KEY_FILE_PATH, 'r') as _file:

    def _get_private_key(self):
        """run generate_keys() before get keys """
        with open(self.PRIVATE_KEY_FILE_PATH, 'r') as _file:

    def _to_format_for_encrypt(value):
        if isinstance(value, int):
            return six.binary_type(value)
        for str_type in six.string_types:
            if isinstance(value, str_type):
                return value.encode('utf8')
        if isinstance(value, six.binary_type):
            return value

And use


class TestingEncryption(RSAEncryption):

# django/flask
from django.core.files import File

class ProductionEncryption(RSAEncryption):

    def _get_private_key(self):
        """run generate_keys() before get keys """
        from corportal.utils import global_elements
        private_key = global_elements.request.FILES.get('private_key')
        if private_key:
            private_key_file = File(private_key)

message = 'Hello ??? friend'
encrypted_mes = ProductionEncryption().encrypt(message)
decrypted_mes = ProductionEncryption().decrypt(message)

How to get local server host and port in Spring Boot?

An easy workaround, at least to get the running port, is to add the parameter javax.servlet.HttpServletRequest in the signature of one of the controller's methods. Once you have the HttpServletRequest instance is straightforward to get the baseUrl with this: request.getRequestURL().toString()

Have a look at this code:

@PostMapping(value = "/registration" , produces = "application/json")
public StringResponse register(@RequestBody RequestUserDTO userDTO, 
    HttpServletRequest request) {
//value: http://localhost:8080/registration
return "";

Print very long string completely in pandas dataframe

The way I often deal with the situation you describe is to use the .to_csv() method and write to stdout:

import sys


Update: it should now be possible to just use None instead of sys.stdout with similar effect!

This should dump the whole dataframe, including the entirety of any strings. You can use the to_csv parameters to configure column separators, whether the index is printed, etc. It will be less pretty than rendering it properly though.

I posted this originally in answer to the somewhat-related question at Output data from all columns in a dataframe in pandas

UnsatisfiedDependencyException: Error creating bean with name 'entityManagerFactory'

The MySQL dependency should be like the following syntax in the pom.xml file.


Make sure the syntax, groupId, artifactId, Version has included in the dependancy.

Manage toolbar's navigation and back button from fragment in android

First you add the Navigation back button


Then, add the Method in your HostActivity.

public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId()
        Toast.makeText(this, "OnBAckPressed Works", Toast.LENGTH_SHORT).show();

    return super.onOptionsItemSelected(item);

Try this, definitely work.

How to access the value of a promise?

You can easily do that using an async wait method in javascript.

Below is an example retrieving a WebRTC promise value using a timeout.

function await_getipv4(timeout = 1000) {_x000D_
    var t1 = new Date();_x000D_
    while(!window.ipv4) {_x000D_
        var stop = new Date() - t1 >= timeout;_x000D_
        if(stop) {_x000D_
            console.error('timeout exceeded for await_getipv4.');_x000D_
            return false;_x000D_
    return window.ipv4;_x000D_
function async_getipv4() {_x000D_
    var ipv4 = null;_x000D_
    var findIP = new Promise(r=>{var w=window,a=new (w.RTCPeerConnection||w.mozRTCPeerConnection||w.webkitRTCPeerConnection)({iceServers:[]}),b=()=>{};a.createDataChannel("");a.createOffer(c=>a.setLocalDescription(c,b,b),b);a.onicecandidate=c=>{try{c.candidate.candidate.match(/([0-9]{1,3}(\.[0-9]{1,3}){3}|[a-f0-9]{1,4}(:[a-f0-9]{1,4}){7})/g).forEach(r)}catch(e){}}})_x000D_
    findIP.then(ip => window.ipv4 = ip);_x000D_
    return await_getipv4();_x000D_

Android - setOnClickListener vs OnClickListener vs View.OnClickListener

Imagine that we have 3 buttons for example

public class MainActivity extends ActionBarActivity {

    protected void onCreate(Bundle savedInstanceState) {


        // Capture our button from layout
        Button button = (Button)findViewById(;
        Button button2 = (Button)findViewById(;
        Button button3 = (Button)findViewById(;
        // Register the onClick listener with the implementation above


    // Create an anonymous implementation of OnClickListener
    private View.OnClickListener mCorkyListener = new View.OnClickListener() {
        public void onClick(View v) {
            // do something when the button is clicked 
            // Yes we will handle click here but which button clicked??? We don't know



So what we will do?

public class MainActivity extends ActionBarActivity {

    protected void onCreate(Bundle savedInstanceState) {


        // Capture our button from layout
        Button button = (Button)findViewById(;
        Button button2 = (Button)findViewById(;
        Button button3 = (Button)findViewById(;
        // Register the onClick listener with the implementation above


    // Create an anonymous implementation of OnClickListener
    private View.OnClickListener mCorkyListener = new View.OnClickListener() {
        public void onClick(View v) {
            // do something when the button is clicked
            // Yes we will handle click here but which button clicked??? We don't know

            // So we will make
            switch (v.getId() /*to get clicked view id**/) {

                    // do something when the corky is clicked


                    // do something when the corky2 is clicked


                    // do something when the corky3 is clicked



Or we can do this:

public class MainActivity extends ActionBarActivity {

    protected void onCreate(Bundle savedInstanceState) {


        // Capture our button from layout
        Button button = (Button)findViewById(;
        Button button2 = (Button)findViewById(;
        Button button3 = (Button)findViewById(;
        // Register the onClick listener with the implementation above
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // do something when the corky is clicked
        button2.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // do something when the corky2 is clicked
        button3.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // do something when the corky3 is clicked



Or we can implement View.OnClickListener and i think it's the best way:

public class MainActivity extends ActionBarActivity implements View.OnClickListener {

    protected void onCreate(Bundle savedInstanceState) {


        // Capture our button from layout
        Button button = (Button)findViewById(;
        Button button2 = (Button)findViewById(;
        Button button3 = (Button)findViewById(;
        // Register the onClick listener with the implementation above


    public void onClick(View v) {
        // do something when the button is clicked
        // Yes we will handle click here but which button clicked??? We don't know

        // So we will make
        switch (v.getId() /*to get clicked view id**/) {

                // do something when the corky is clicked


                // do something when the corky2 is clicked


                // do something when the corky3 is clicked


Finally there is no real differences here Just "Way better than the other"

How to fix Invalid AES key length?

You can use this code, this code is for AES-256-CBC or you can use it for other AES encryption. Key length error mainly comes in 256-bit encryption.

This error comes due to the encoding or charset name we pass in the SecretKeySpec. Suppose, in my case, I have a key length of 44, but I am not able to encrypt my text using this long key; Java throws me an error of invalid key length. Therefore I pass my key as a BASE64 in the function, and it converts my 44 length key in the 32 bytes, which is must for the 256-bit encryption.

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

public class Encrypt {

    static byte [] arr = {1,2,3,4,5,6,7,8,9};

    // static byte [] arr = new byte[16];

      public static void main(String...args) {
        try {
         //   System.out.println(Cipher.getMaxAllowedKeyLength("AES"));
            Base64.Decoder decoder = Base64.getDecoder();
            // static byte [] arr = new byte[16];
            Security.setProperty("crypto.policy", "unlimited");
            String key = "Your key";
       //     System.out.println("-------" + key);

            String value = "Hey, i am adnan";
            String IV = "0123456789abcdef";
       //     System.out.println(value);
          IvParameterSpec iv = new IvParameterSpec(IV.getBytes());
            //    IvParameterSpec iv = new IvParameterSpec(arr);

        //    System.out.println(key);
            SecretKeySpec skeySpec = new SecretKeySpec(decoder.decode(key), "AES");
         //   System.out.println(skeySpec);
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        //    System.out.println("ddddddddd"+IV);
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
       //     System.out.println(cipher.getIV());

            byte[] encrypted = cipher.doFinal(value.getBytes());
            String encryptedString = Base64.getEncoder().encodeToString(encrypted);

            System.out.println("encrypted string,,,,,,,,,,,,,,,,,,,: " + encryptedString);
            // vars.put("input-1",encryptedString);
        }catch (Exception e){

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'id' in 'where clause' (SQL: select * from `songs` where `id` = 5 limit 1)

When you use find(), it automatically assumes your primary key column is going to be id. In order for this to work correctly, you should set your primary key in your model.

So in Song.php, within the class, add the line...

protected $primaryKey = 'SongID';

If there is any possibility of changing your schema, I'd highly recommend naming all your primary key columns id, it's what Laravel assumes and will probably save you from more headaches down the road.

R Markdown - changing font size and font type in html output

I would definitely use html markers to achieve this. Just surround your text with <p></p> or <font></font> and add the desired attributes. See the following example:

<p style="font-family: times, serif; font-size:11pt; font-style:italic">
    Why did we use these specific parameters during the calculation of the fingerprints?

This will produce the following output

Font Output

compared to

Default Output

This would work with Jupyter Notebook as well as Typora, but I'm not sure if it is universal.

Lastly, be aware that the html marker overrides the font styling used by Markdown.

Can't Autowire @Repository annotated interface in Spring Boot

Here is the mistake: as someone said before, you are using insted of in componentscan

    package **com**.pharmacy.config;

    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.context.annotation.ComponentScan;

    public class SpringBootRunner {

Trying to get Laravel 5 email to work

That simply means that your server does not have access to the SMTP Server.

You can test this by doing:

telnet <smtpServer> <smtpPort>

You should get the Access denied error.

The solution is to just use another SMTP server that can be accessed by your server.

Error:Execution failed for task ':ProjectName:mergeDebugResources'. > Crunching Cruncher *some file* failed, see logs

The problem might probably be due to the mismatch of the extension types given by the programmer and the actual extensions of the images present in the drawable folder of your app. or fixing this follow the steps given below:-

Step 1- Double click on each of the image resources and and check the extension i.e whether the image is png or jpeg or any other format.

Step 2- Now check if the same extension is given by you in the drawable folder dropdown in package explorer(a.k.a Android in Android Studio).

Step 3 - If the extensions are not matching then delete that image and paste another image of the same name in its place making sure the extension is matching with the actual extension of the image (for example, if the image is "a.png" then make sure the extension of the image given by you is also of .png type) .

Step 4 - Sync your gradle file and run the project. This time there should be no errors.

setSupportActionBar toolbar cannot be applied to (android.widget.Toolbar) error

For Android version above 3:

import androidx.appcompat.widget.Toolbar;

For Android version below 3:

import android.widget.Toolbar;

What is wrong with my SQL here? #1089 - Incorrect prefix key

If you are using a GUI and you are still getting the same problem. Just leave the size value empty, the primary key defaults the value to 11, you should be fine with this. Worked with Bitnami phpmyadmin.

Difference and uses of onCreate(), onCreateView() and onActivityCreated() in fragments

onActivityCreated() - Deprecated

onActivityCreated() is now deprecated as Fragments Version 1.3.0-alpha02

The onActivityCreated() method is now deprecated. Code touching the fragment's view should be done in onViewCreated() (which is called immediately before onActivityCreated()) and other initialization code should be in onCreate(). To receive a callback specifically when the activity's onCreate() is complete, a LifeCycleObserver should be registered on the activity's Lifecycle in onAttach(), and removed once the onCreate() callback is received.

Detailed information can be found here

How to wait for a JavaScript Promise to resolve before resuming function?

If using ES2016 you can use async and await and do something like:

(async () => {
  const data = await fetch(url)

If using ES2015 you can use Generators. If you don't like the syntax you can abstract it away using an async utility function as explained here.

If using ES5 you'll probably want a library like Bluebird to give you more control.

Finally, if your runtime supports ES2015 already execution order may be preserved with parallelism using Fetch Injection.

How to open a different activity on recyclerView item onclick

The problem occurs in declaring context, while using Glide for ImageView or While using intent in recyclerview for item onClick. I Found this working for me which helps me to Declare context to use in Glide or Intent or Toast.

public class NoteAdapter extends FirestoreRecyclerAdapter<Note,NoteAdapter.NoteHolder> {

Context context;

public NoteAdapter(@NonNull FirestoreRecyclerOptions<Note> options) {

protected void onBindViewHolder(@NonNull NoteHolder holder, int position, @NonNull Note model) {

    context = holder.itemView.getContext();

    holder.itemView.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Intent i = new Intent(context, SuggestActivity.class);


public NoteHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_category,parent,false);

    return new NoteHolder(v);

public static class NoteHolder extends RecyclerView.ViewHolder
    TextView r_tv;
    ImageView r_iv;

    public NoteHolder(@NonNull View itemView) {

        r_tv = itemView.findViewById(;
        r_iv = itemView.findViewById(;


Hadoop cluster setup - Connection refused

In my experaince

15/02/22 18:23:04 WARN util.NativeCodeLoader: Unable to load native-hadoop
library for your platform... using builtin-java classes where applicable

You may have 64 bit version OS, and hadoop installation 32bit. refer this Call From marta-komputer/ to
localhost:9000 failed on connection exception: 
connection refused; For more details see:

this problem refers to your ssh public key authorization. please provide details about your ssh set up.

Please refer this link to check the complete steps.

also provide info if

cat $HOME/.ssh/authorized_keys

returns any result or not.

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference

it sometimes occurs when we use a custom adapter in any activity of fragment . and we return null object i.e null view so the activity gets confused which view to load , so that is why this exception occurs

shows the position where to change the view

Base64: java.lang.IllegalArgumentException: Illegal character

Just use the below code to resolve this:

JsonObject obj = Json.createReader(new ByteArrayInputStream(Base64.getDecoder().decode(accessToken.split("\\.")[1].
                        replace('-', '+').replace('_', '/')))).readObject();

In the above code replace('-', '+').replace('_', '/') did the job. For more details see the I understood the problem from the part of the code got from that link:

function url_base64_decode(str) {
  var output = str.replace(/-/g, '+').replace(/_/g, '/');
  switch (output.length % 4) {
    case 0:
    case 2:
      output += '==';
    case 3:
      output += '=';
      throw 'Illegal base64url string!';
  var result = window.atob(output); //polifyll
    return decodeURIComponent(escape(result));
  } catch (err) {
    return result;

How to return first 5 objects of Array in Swift?


A different solution:

An easy inline solution that wont crash if your array is too short

[0,1,2,3,4,5].enumerated().compactMap{ $0.offset < 3 ? $0.element : nil }

But works fine with this.

[0,1,2,3,4,5].enumerated().compactMap{ $0.offset < 1000 ? $0.element : nil }

Usually this would crash if you did this:

[0,1,2,3,4,5].prefix(upTo: 1000) // THIS CRASHES

[0,1,2,3,4,5].prefix(1000) // THIS DOESNT

Open web in new tab Selenium + Python

I'd stick to ActionChains for this.

Here's a function which opens a new tab and switches to that tab:

import time
from selenium.webdriver.common.action_chains import ActionChains

def open_in_new_tab(driver, element, switch_to_new_tab=True):
    base_handle = driver.current_window_handle
    # Do some actions
    ActionChains(driver) \
        .move_to_element(element) \
        .key_down(Keys.COMMAND) \
        .click() \
        .key_up(Keys.COMMAND) \
    # Should you switch to the new tab?
    if switch_to_new_tab:
        new_handle = [x for x in driver.window_handles if x!=base_handle]
        assert len new_handle == 1 # assume you are only opening one tab at a time
        # Switch to the new window

        # I like to wait after switching to a new tab for the content to load
        # Do that either with time.sleep() or with WebDriverWait until a basic
        # element of the page appears (such as "body") -- reference for this is 
        # provided below

        # NOTE: if you choose to switch to the window/tab, be sure to close
        # the newly opened window/tab after using it and that you switch back
        # to the original "base_handle" --> otherwise, you'll experience many
        # errors and a painful debugging experience...

Here's how you would apply that function:

# Remember your starting handle
base_handle = driver.current_window_handle

# Say we have a list of elements and each is a link:
links = driver.find_elements_by_css_selector('a[href]')

# Loop through the links and open each one in a new tab
for link in links:
    open_in_new_tab(driver, link, True)
    # Do something on this new page
    # Once you're finished, close this tab and switch back to the original one
    # You're ready to continue to the next item in your loop

Here's how you could wait until the page is loaded.

How do you round a double in Dart to a given degree of precision AFTER the decimal point?

See the docs for num.toStringAsFixed().

String toStringAsFixed(int fractionDigits)

Returns a decimal-point string-representation of this.

Converts this to a double before computing the string representation.

  • If the absolute value of this is greater or equal to 10^21 then this methods returns an exponential representation computed by this.toStringAsExponential().


1000000000000000000000.toStringAsExponential(3); // 1.000e+21
  • Otherwise the result is the closest string representation with exactly fractionDigits digits after the decimal point. If fractionDigits equals 0 then the decimal point is omitted.

The parameter fractionDigits must be an integer satisfying: 0 <= fractionDigits <= 20.


1.toStringAsFixed(3);  // 1.000
(4321.12345678).toStringAsFixed(3);  // 4321.123
(4321.12345678).toStringAsFixed(5);  // 4321.12346
123456789012345678901.toStringAsFixed(3);  // 123456789012345683968.000
1000000000000000000000.toStringAsFixed(3); // 1e+21
5.25.toStringAsFixed(0); // 5

No connection could be made because the target machine actively refused it

There is a firewall blocking the connection or the process that is hosting the service is not listening on that port. Or it is listening on a different port.

How to customise the Jackson JSON mapper implicitly used by Spring Boot?

I know the question asking for Spring boot, but I believe lot of people looking for how to do this in non Spring boot, like me searching almost whole day.

Above Spring 4, there is no need to configure MappingJacksonHttpMessageConverter if you only intend to configure ObjectMapper.

You just need to do:

public class MyObjectMapper extends ObjectMapper {

    private static final long serialVersionUID = 4219938065516862637L;

    public MyObjectMapper() {

And in your Spring configuration, create this bean:

public MyObjectMapper myObjectMapper() {        
    return new MyObjectMapper();

gpg decryption fails with no secret key error

Following this procedure worked for me.

To create gpg key. gpg --gen-key --homedir /etc/salt/gpgkeys

export the public key, secret key, and secret subkey.

gpg --homedir /etc/salt/gpgkeys --export test-key > pub.key
gpg --homedir /etc/salt/gpgkeys --export-secret-keys test-key > sec.key
gpg --homedir /etc/salt/gpgkeys --export-secret-subkeys test-key > sub.key

Now import the keys using the following command.

gpg --import pub.key
gpg --import sec.key
gpg --import sub.key

Verify if the keys are imported.

gpg --list-keys
gpg --list-secret-keys

Create a sample file.

echo "hahaha" > a.txt

Encrypt the file using the imported key

gpg --encrypt --sign --armor -r test-key a.txt

To decrypt the file, use the following command.

gpg --decrypt a.txt.asc

Null pointer Exception on .setOnClickListener

Submit is null because it is not part of activity_main.xml

When you call findViewById inside an Activity, it is going to look for a View inside your Activity's layout.

try this instead :

Submit = (Button)loginDialog.findViewById(;

Another thing : you use


but what you want is probably


See this question about the difference between @id and @+id.

7-Zip command to create and extract a password-protected ZIP file on Windows?


7z a secure.7z * -pSECRET


7z        : name and path of 7-Zip executable
a         : add to archive
secure.7z : name of destination archive
*         : add all files from current directory to destination archive
-pSECRET  : specify the password "SECRET"

To open :

7z x secure.7z

Then provide the SECRET password

Note: If the password contains spaces or special characters, then enclose it with single quotes

7z a secure.7z * -p"pa$$word @|"

Android Error [Attempt to invoke virtual method 'void' on a null object reference]

I got the same error once, I created a template for a default toolbar( toolbar.xml) and then in another view I created a collapsable toolbar.

I required to add the collapsable toolbar to a view that show some information of the user(like whatsapp), but the method findViewById was referencing the default toolbar(id toolbar), not the collapsable one( id toolbar as well) yes, I wrote the same id to both toolbar, so when I tried to access the activity the app crashed showing me the error.

I fixed the error by changing the id of the collapsable toolbar to id:col_toolbar and the error gone away and my app worked perfectly

Spring Boot - Error creating bean with name 'dataSource' defined in class path resource

Are you running the application as a jar? ( java -jar xxxx.jar)

If so, do you have the stored in that jar ?

If no, try to figure out why :

  • To be automatically package in the jar, the files can be in : src/main/resources/
  • The maven plugin in the pom.xml can also be configured

- java.lang.NullPointerException - setText on null object reference

The problem is the tv.setText(text). The variable tv is probably null and you call the setText method on that null, which you can't. My guess that the problem is on the findViewById method, but it's not here, so I can't tell more, without the code.

NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equalsIgnoreCase(java.lang.String)' on a null object reference

The exception occurs due to this statement,


It seem that the previous statement

String called_from = getIntent().getStringExtra("called");

returned a null reference.

You can check whether the intent to start this activity contains such a key "called".

Add a new item to recyclerview programmatically?

simply add to your data structure ( mItems ) , and then notify your adapter about dataset change

private void addItem(String item) {

addItem("New Item");

JWT refresh token flow

Based in this implementation with Node.js of JWT with refresh token:

1) In this case they use a uid and it's not a JWT. When they refresh the token they send the refresh token and the user. If you implement it as a JWT, you don't need to send the user, because it would inside the JWT.

2) They implement this in a separated document (table). It has sense to me because a user can be logged in in different client applications and it could have a refresh token by app. If the user lose a device with one app installed, the refresh token of that device could be invalidated without affecting the other logged in devices.

3) In this implementation it response to the log in method with both, access token and refresh token. It seams correct to me.

How can I scroll up more (increase the scroll buffer) in iTerm2?

There is an option “unlimited scrollback buffer” which you can find under Preferences > Profiles > Terminal or you can just pump up number of lines that you want to have in history in the same place.

How do I make WRAP_CONTENT work on a RecyclerView

I have not worked on my answer but the way I know it StaggridLayoutManager with no. of grid 1 can solve your problem as StaggridLayout will automatically adjust its height and width on the size of the content. if it works dont forget to check it as a right answer.Cheers..

How do I append to a table in Lua

I'd personally make use of the table.insert function:


This saves you from having to iterate over the whole table therefore saving valuable resources such as memory and time.

Cannot resolve method 'getSupportFragmentManager ( )' inside Fragment

you should use

getActivity.getSupportFragmentManager() like
//in my fragment 
SupportMapFragment fm = (SupportMapFragment)    

I have also this issues but resolved after adding getActivity() before getSupportFragmentManager.

java.lang.NullPointerException: Attempt to invoke virtual method on a null object reference

Your app is crashing at:

welcomePlayer.setText("Welcome Back, " + String.valueOf(mPlayer.getName(this)) + " !");

because mPlayer=null.

You forgot to initialize Player mPlayer in your PlayGame Activity.

mPlayer = new Player(context,"");

How to use SearchView in Toolbar Android

You have to use Appcompat library for that. Which is used like below:


<menu xmlns:android="" 


Activity file (in Java):

public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater menuInflater = getMenuInflater();
    menuInflater.inflate(, menu);

     MenuItem searchItem = menu.findItem(;

    SearchManager searchManager = (SearchManager) MainActivity.this.getSystemService(Context.SEARCH_SERVICE);

    SearchView searchView = null;
    if (searchItem != null) {
        searchView = (SearchView) searchItem.getActionView();
    if (searchView != null) {
        return super.onCreateOptionsMenu(menu);

Activity file (in Kotlin):

override fun onCreateOptionsMenu(menu: Menu?): Boolean {
    menuInflater.inflate(, menu)

    val searchItem: MenuItem? = menu?.findItem(
    val searchManager = getSystemService(Context.SEARCH_SERVICE) as SearchManager
    val searchView: SearchView? = searchItem?.actionView as SearchView

    return super.onCreateOptionsMenu(menu)

manifest file:

      android:value="com.apkgetter.SearchResultsActivity" /> 

            android:launchMode="singleTop" >
                <action android:name="android.intent.action.SEARCH" />
                <action android:name="android.intent.action.VIEW" />

                android:resource="@xml/searchable" />

searchable xml file:

<?xml version="1.0" encoding="utf-8"?>
<searchable xmlns:android=""
    android:label="@string/app_name" />

And at last, your SearchResultsActivity class code. for showing result of your search.

Android: remove left margin from actionbar's custom layout

Setting "contentInset..." attributes to 0 in the Toolbar didn't work for me. Nilesh Senta's solution to update the style worked!


<style name="AppTheme" parent="Theme.AppCompat.Light">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
    <item name="actionBarStyle">@style/Actionbar</item>
    <item name="android:titleTextStyle">@style/ActionbarTitle</item>

<style name="Actionbar" parent="Widget.AppCompat.ActionBar">
    <item name="contentInsetStart">0dp</item>
    <item name="contentInsetEnd">0dp</item>

java (onCreate)

ActionBar actionBar =  getSupportActionBar();


ActionBar.LayoutParams layoutParams = new ActionBar.LayoutParams(

View view = LayoutInflater.from(this).inflate(R.layout.actionbar_main, null);

actionBar.setCustomView(view, layoutParams);

How do I encrypt and decrypt a string in python?

Although its very old, but I thought of sharing another idea to do this:

from Crypto.Cipher import AES    
from Crypto.Hash import SHA256

password = ("anything")    
hash_obj ='utf-8'))    
hkey = hash_obj.digest()

def encrypt(info):
    msg = info
    BLOCK_SIZE = 16
    PAD = "{"
    padding = lambda s: s + (BLOCK_SIZE - len(s) % BLOCK_SIZE) * PAD
    cipher =, AES.MODE_ECB)
    result = cipher.encrypt(padding(msg).encode('utf-8'))
    return result  

msg = "Hello stackoverflow!"
cipher_text = encrypt(msg)

def decrypt(info):
    msg = info
    PAD = "{"
    decipher =, AES.MODE_ECB)
    pt = decipher.decrypt(msg).decode('utf-8')
    pad_index = pt.find(PAD)
    result = pt[: pad_index]
    return result

plaintext = decrypt(cipher_text)


> b'\xcb\x0b\x8c\xdc#\n\xdd\x80\xa6|\xacu\x1dEg;\x8e\xa2\xaf\x80\xea\x95\x80\x02\x13\x1aem\xcb\xf40\xdb'

> Hello stackoverflow!

NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference


 mAdapter = new RecordingsListAdapter(this, recordings);


 mAdapter = new RecordingsListAdapter(getActivity(), recordings);

and also make sure that recordings!=null at mAdapter = new RecordingsListAdapter(this, recordings);

Unable to add window -- token null is not valid; is your activity running?

You need to pass your activity in the constructor

 PopupWindow popupWindow = new PopupWindow(YourActivity.this)

AES Encrypt and Decrypt

CryptoSwift is very interesting project but for now it has some AES speed limitations. Be carefull if you need to do some serious crypto - it might be worth to go through the pain of bridge implemmenting CommonCrypto.

BigUps to Marcin for pureSwift implementation

How to fix symbol lookup error: undefined symbol errors in a cluster environment

yum update

helped me out. After I had

wget: symbol lookup error: wget: undefined symbol: psl_latest

How to get Toolbar from fragment?

You need to cast your activity from getActivity() to AppCompatActivity first. Here's an example:

((AppCompatActivity) getActivity()).getSupportActionBar().setTitle();

The reason you have to cast it is because getActivity() returns a FragmentActivity and you need an AppCompatActivity

In Kotlin:

(activity as AppCompatActivity).supportActionBar?.title = "My Title"

Python NLTK: SyntaxError: Non-ASCII character '\xc3' in file (Sentiment Analysis -NLP)

Add the following to the top of your file # coding=utf-8

If you go to the link in the error you can seen the reason why:

Defining the Encoding

Python will default to ASCII as standard encoding if no other encoding hints are given. To define a source code encoding, a magic comment must be placed into the source files either as first or second line in the file, such as: # coding=

Tomcat 8 throwing - org.apache.catalina.webresources.Cache.getResource Unable to add the resource

I had the same issue when upgrading from Tomcat 7 to 8: a continuous large flood of log warnings about cache.

1. Short Answer

Add this within the Context xml element of your $CATALINA_BASE/conf/context.xml:

<!-- The default value is 10240 kbytes, even when not added to context.xml.
So increase it high enough, until the problem disappears, for example set it to 
a value 5 times as high: 51200. -->
<Resources cacheMaxSize="51200" />

So the default is 10240 (10 mbyte), so set a size higher than this. Than tune for optimum settings where the warnings disappear. Note that the warnings may come back under higher traffic situations.

1.1 The cause (short explanation)

The problem is caused by Tomcat being unable to reach its target cache size due to cache entries that are less than the TTL of those entries. So Tomcat didn't have enough cache entries that it could expire, because they were too fresh, so it couldn't free enough cache and thus outputs warnings.

The problem didn't appear in Tomcat 7 because Tomcat 7 simply didn't output warnings in this situation. (Causing you and me to use poor cache settings without being notified.)

The problem appears when receiving a relative large amount of HTTP requests for resources (usually static) in a relative short time period compared to the size and TTL of the cache. If the cache is reaching its maximum (10mb by default) with more than 95% of its size with fresh cache entries (fresh means less than less than 5 seconds in cache), than you will get a warning message for each webResource that Tomcat tries to load in the cache.

1.2 Optional info

Use JMX if you need to tune cacheMaxSize on a running server without rebooting it.

The quickest fix would be to completely disable cache: <Resources cachingAllowed="false" />, but that's suboptimal, so increase cacheMaxSize as I just described.

2. Long Answer

2.1 Background information

A WebSource is a file or directory in a web application. For performance reasons, Tomcat can cache WebSources. The maximum of the static resource cache (all resources in total) is by default 10240 kbyte (10 mbyte). A webResource is loaded into the cache when the webResource is requested (for example when loading a static image), it's then called a cache entry. Every cache entry has a TTL (time to live), which is the time that the cache entry is allowed to stay in the cache. When the TTL expires, the cache entry is eligible to be removed from the cache. The default value of the cacheTTL is 5000 milliseconds (5 seconds).

There is more to tell about caching, but that is irrelevant for the problem.

2.2 The cause

The following code from the Cache class shows the caching policy in detail:

152  // Content will not be cached but we still need metadata size
153 long delta = cacheEntry.getSize();
154 size.addAndGet(delta);
156 if (size.get() > maxSize) {
157 // Process resources unordered for speed. Trades cache
158 // efficiency (younger entries may be evicted before older
159 // ones) for speed since this is on the critical path for
160 // request processing
161 long targetSize =
162 maxSize * (100 - TARGET_FREE_PERCENT_GET) / 100;
163 long newSize = evict(
164 targetSize, resourceCache.values().iterator());
165 if (newSize > maxSize) {
166 // Unable to create sufficient space for this resource
167 // Remove it from the cache
168 removeCacheEntry(path);
169 log.warn(sm.getString("cache.addFail", path));
170 }
171 }

When loading a webResource, the code calculates the new size of the cache. If the calculated size is larger than the default maximum size, than one or more cached entries have to be removed, otherwise the new size will exceed the maximum. So the code will calculate a "targetSize", which is the size the cache wants to stay under (as an optimum), which is by default 95% of the maximum. In order to reach this targetSize, entries have to be removed/evicted from the cache. This is done using the following code:

215  private long evict(long targetSize, Iterator<CachedResource> iter) {
217 long now = System.currentTimeMillis();
219 long newSize = size.get();
221 while (newSize > targetSize && iter.hasNext()) {
222 CachedResource resource =;
224 // Don't expire anything that has been checked within the TTL
225 if (resource.getNextCheck() > now) {
226 continue;
227 }
229 // Remove the entry from the cache
230 removeCacheEntry(resource.getWebappPath());
232 newSize = size.get();
233 }
235 return newSize;
236 }

So a cache entry is removed when its TTL is expired and the targetSize hasn't been reached yet.

After the attempt to free cache by evicting cache entries, the code will do:

165  if (newSize > maxSize) {
166 // Unable to create sufficient space for this resource
167 // Remove it from the cache
168 removeCacheEntry(path);
169 log.warn(sm.getString("cache.addFail", path));
170 }

So if after the attempt to free cache, the size still exceeds the maximum, it will show the warning message about being unable to free:

cache.addFail=Unable to add the resource at [{0}] to the cache for web application [{1}] because there was insufficient free space available after evicting expired cache entries - consider increasing the maximum size of the cache

2.3 The problem

So as the warning message says, the problem is

insufficient free space available after evicting expired cache entries - consider increasing the maximum size of the cache

If your web application loads a lot of uncached webResources (about maximum of cache, by default 10mb) within a short time (5 seconds), then you'll get the warning.

The confusing part is that Tomcat 7 didn't show the warning. This is simply caused by this Tomcat 7 code:

1606  // Add new entry to cache
1607 synchronized (cache) {
1608 // Check cache size, and remove elements if too big
1609 if ((cache.lookup(name) == null) && cache.allocate(entry.size)) {
1610 cache.load(entry);
1611 }
1612 }

combined with:

231  while (toFree > 0) {
232 if (attempts == maxAllocateIterations) {
233 // Give up, no changes are made to the current cache
234 return false;
235 }

So Tomcat 7 simply doesn't output any warning at all when it's unable to free cache, whereas Tomcat 8 will output a warning.

So if you are using Tomcat 8 with the same default caching configuration as Tomcat 7, and you got warnings in Tomcat 8, than your (and mine) caching settings of Tomcat 7 were performing poorly without warning.

2.4 Solutions

There are multiple solutions:

  1. Increase cache (recommended)
  2. Lower the TTL (not recommended)
  3. Suppress cache log warnings (not recommended)
  4. Disable cache

2.4.1. Increase cache (recommended)

As described here:

By adding <Resources cacheMaxSize="XXXXX" /> within the Context element in $CATALINA_BASE/conf/context.xml, where "XXXXX" stands for an increased cache size, specified in kbytes. The default is 10240 (10 mbyte), so set a size higher than this.

You'll have to tune for optimum settings. Note that the problem may come back when you suddenly have an increase in traffic/resource requests.

To avoid having to restart the server every time you want to try a new cache size, you can change it without restarting by using JMX.

To enable JMX, add this to $CATALINA_BASE/conf/server.xml within the Server element: <Listener className="org.apache.catalina.mbeans.JmxRemoteLifecycleListener" rmiRegistryPortPlatform="6767" rmiServerPortPlatform="6768" /> and download catalina-jmx-remote.jar from and put it in $CATALINA_HOME/lib. Then use jConsole (shipped by default with the Java JDK) to connect over JMX to the server and look through the settings for settings to increase the cache size while the server is running. Changes in these settings should take affect immediately.

2.4.2. Lower the TTL (not recommended)

Lower the cacheTtl value by something lower than 5000 milliseconds and tune for optimal settings.

For example: <Resources cacheTtl="2000" />

This comes effectively down to having and filling a cache in ram without using it.

2.4.3. Suppress cache log warnings (not recommended)

Configure logging to disable the logger for org.apache.catalina.webresources.Cache.

For more info about logging in Tomcat:

2.4.4. Disable cache

You can disable the cache by setting cachingAllowed to false. <Resources cachingAllowed="false" />

Although I can remember that in a beta version of Tomcat 8, I was using JMX to disable the cache. (Not sure why exactly, but there may be a problem with disabling the cache via server.xml.)

How to add buttons like refresh and search in ToolBar in Android?

Try to do this:


and if you made your custom toolbar (which i presume you did) then you can use the simplest way possible to do this:

toolbarTitle = (TextView)findViewById(;
toolbarSubTitle = (TextView)findViewById(;

Same goes for any other views you put in your toolbar. Hope it helps.

How to edit nginx.conf to increase file size upload

Add client_max_body_size

Now that you are editing the file you need to add the line into the server block, like so;

server {
    client_max_body_size 8M;

    //other lines...

If you are hosting multiple sites add it to the http context like so;

http {
    client_max_body_size 8M;

    //other lines...

And also update the upload_max_filesize in your php.ini file so that you can upload files of the same size.

Saving in Vi

Once you are done you need to save, this can be done in vi with pressing esc key and typing :wq and returning.

Restarting Nginx and PHP

Now you need to restart nginx and php to reload the configs. This can be done using the following commands;

sudo service nginx restart
sudo service php5-fpm restart

Or whatever your php service is called.

How do I get the position selected in a RecyclerView?

public void onClick(View v) {
     int pos = getAdapterPosition();

Simple as that, on ViewHolder

Installing NumPy and SciPy on 64-bit Windows (with Pip)

Package version are very important.

I found some stable combination that works on my Windows10 64 bit machine:

pip install numpy-1.12.0+mkl-cp36-cp36m-win64.whl
pip install scipy-0.18.1-cp36-cp36m-win64.whl
pip install matplotlib-2.0.0-cp36-cp36m-win64.whl


Nested Recycler view height doesn't wrap its content

As @yigit mentioned, you need to override onMeasure(). Both @user2302510 and @DenisNek have good answers but if you want to support ItemDecoration you can use this custom layout manager.

And other answers cannot scroll when there are more items than can be displayed on the screen though. This one is using default implemantation of onMeasure() when there are more items than screen size.

public class MyLinearLayoutManager extends LinearLayoutManager {

public MyLinearLayoutManager(Context context, int orientation, boolean reverseLayout)    {
    super(context, orientation, reverseLayout);

private int[] mMeasuredDimension = new int[2];

public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
                      int widthSpec, int heightSpec) {
    final int widthMode = View.MeasureSpec.getMode(widthSpec);
    final int heightMode = View.MeasureSpec.getMode(heightSpec);
    final int widthSize = View.MeasureSpec.getSize(widthSpec);
    final int heightSize = View.MeasureSpec.getSize(heightSpec);
    int width = 0;
    int height = 0;
    for (int i = 0; i < getItemCount(); i++) {
        measureScrapChild(recycler, i,
                View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),

        if (getOrientation() == HORIZONTAL) {
            width = width + mMeasuredDimension[0];
            if (i == 0) {
                height = mMeasuredDimension[1];
        } else {
            height = height + mMeasuredDimension[1];
            if (i == 0) {
                width = mMeasuredDimension[0];

    // If child view is more than screen size, there is no need to make it wrap content. We can use original onMeasure() so we can scroll view.
    if (height < heightSize && width < widthSize) {

        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
                width = widthSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:

        switch (heightMode) {
            case View.MeasureSpec.EXACTLY:
                height = heightSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:

        setMeasuredDimension(width, height);
    } else {
        super.onMeasure(recycler, state, widthSpec, heightSpec);

private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                               int heightSpec, int[] measuredDimension) {

   View view = recycler.getViewForPosition(position);

   // For adding Item Decor Insets to view
   super.measureChildWithMargins(view, 0, 0);
    if (view != null) {
        RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
        int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                    getPaddingLeft() + getPaddingRight() + getDecoratedLeft(view) + getDecoratedRight(view), p.width);
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                    getPaddingTop() + getPaddingBottom() + getPaddingBottom() + getDecoratedBottom(view) , p.height);
            view.measure(childWidthSpec, childHeightSpec);

            // Get decorated measurements
            measuredDimension[0] = getDecoratedMeasuredWidth(view) + p.leftMargin + p.rightMargin;
            measuredDimension[1] = getDecoratedMeasuredHeight(view) + p.bottomMargin + p.topMargin;

And if you want to use it with GridLayoutManager just extends it from GridLayoutManager and change

for (int i = 0; i < getItemCount(); i++)


for (int i = 0; i < getItemCount(); i = i + getSpanCount())

Display a RecyclerView in Fragment

This was asked some time ago now, but based on the answer that @nacho_zona3 provided, and previous experience with fragments, the issue is that the views have not been created by the time you are trying to find them with the findViewById() method in onCreate() to fix this, move the following code:

// 1. get a reference to recyclerView
RecyclerView recyclerView = (RecyclerView) findViewById(;

// 2. set layoutManger
recyclerView.setLayoutManager(new LinearLayoutManager(this));

// this is data fro recycler view
ItemData itemsData[] = { new ItemData("Indigo",,
        new ItemData("Red",R.drawable.color_ic_launcher),
        new ItemData("Blue",R.drawable.indigo),
        new ItemData("Green",,
        new ItemData("Amber",R.drawable.color_ic_launcher),
        new ItemData("Deep Orange",R.drawable.indigo)};

// 3. create an adapter
MyAdapter mAdapter = new MyAdapter(itemsData);
// 4. set adapter
// 5. set item animator to DefaultAnimator
recyclerView.setItemAnimator(new DefaultItemAnimator()); 

to your fragment's onCreateView() call. A small amount of refactoring is required because all variables and methods called from this method have to be static. The final code should look like:

 public class ColorsFragment extends Fragment {

     public ColorsFragment() {}

     public View onCreateView(LayoutInflater inflater, ViewGroup container,
         Bundle savedInstanceState) {

         View rootView = inflater.inflate(R.layout.fragment_colors, container, false);
         // 1. get a reference to recyclerView
         RecyclerView recyclerView = (RecyclerView) rootView.findViewById(;

         // 2. set layoutManger
         recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

         // this is data fro recycler view
         ItemData itemsData[] = {
             new ItemData("Indigo",,
                 new ItemData("Red", R.drawable.color_ic_launcher),
                 new ItemData("Blue", R.drawable.indigo),
                 new ItemData("Green",,
                 new ItemData("Amber", R.drawable.color_ic_launcher),
                 new ItemData("Deep Orange", R.drawable.indigo)

         // 3. create an adapter
         MyAdapter mAdapter = new MyAdapter(itemsData);
         // 4. set adapter
         // 5. set item animator to DefaultAnimator
         recyclerView.setItemAnimator(new DefaultItemAnimator());

         return rootView;

So the main thing here is that anywhere you call findViewById() you will need to use rootView.findViewById()

How to convert WebResponse.GetResponseStream return into a string?

As @Heinzi mentioned the character set of the response should be used.

var encoding = response.CharacterSet == ""
    ? Encoding.UTF8
    : Encoding.GetEncoding(response.CharacterSet);

using (var stream = response.GetResponseStream())
    var reader = new StreamReader(stream, encoding);
    var responseString = reader.ReadToEnd();

ASP.NET MVC controller actions that return JSON or partial html

In your action method, return Json(object) to return JSON to your page.

public ActionResult SomeActionMethod() {
  return Json(new {foo="bar", baz="Blech"});

Then just call the action method using Ajax. You could use one of the helper methods from the ViewPage such as

<%= Ajax.ActionLink("SomeActionMethod", new AjaxOptions {OnSuccess="somemethod"}) %>

SomeMethod would be a javascript method that then evaluates the Json object returned.

If you want to return a plain string, you can just use the ContentResult:

public ActionResult SomeActionMethod() {
    return Content("hello world!");

ContentResult by default returns a text/plain as its contentType.
This is overloadable so you can also do:

return Content("<xml>This is poorly formatted xml.</xml>", "text/xml");

Text on image mouseover?

For people coming from the future, you can now do this purely in CSS.

.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: 1px dotted black; 
  margin: 5rem;

/* Tooltip text */
.tooltip .tooltiptext {
  visibility: hidden;
  background-color: black;
  color: #fff;
  text-align: center;
  padding: 5px 0;
  border-radius: 6px;

  width: 120px;
  bottom: 100%;
  left: 50%;
  margin-left: -60px;

  position: absolute;
  z-index: 1;

/* Show the tooltip text when you mouse over the tooltip container */
.tooltip:hover .tooltiptext {
  visibility: visible;
<div class="tooltip">Hover over me
  <span class="tooltiptext">Tooltip text</span>

Using String Format to show decimal up to 2 places or simple integer

If your program needs to run quickly, call value.ToString(formatString) for ~35% faster string formatting performance relative to $"{value:formatString}" and string.Format(formatString, value).


C# String Formatting Performance - VS2017 15.4.5


using System;
using System.Diagnostics;

public static class StringFormattingPerformance
   public static void Main()
      Console.WriteLine("C# String Formatting Performance");
      Console.WriteLine("Milliseconds Per 1 Million Iterations - Best Of 5");
      long stringInterpolationBestOf5 = Measure1MillionIterationsBestOf5(
          (double randomDouble) =>
             return $"{randomDouble:0.##}";
      long stringDotFormatBestOf5 = Measure1MillionIterationsBestOf5(
          (double randomDouble) =>
             return string.Format("{0:0.##}", randomDouble);
      long valueDotToStringBestOf5 = Measure1MillionIterationsBestOf5(
          (double randomDouble) =>
             return randomDouble.ToString("0.##");
$@"            $""{{value:formatString}}"": {stringInterpolationBestOf5} ms
 string.Format(formatString, value): {stringDotFormatBestOf5} ms
       value.ToString(formatString): {valueDotToStringBestOf5} ms");

   private static long Measure1MillionIterationsBestOf5(
       Func<double, string> formatDoubleUpToTwoDecimalPlaces)
      long elapsedMillisecondsBestOf5 = long.MaxValue;
      for (int perfRunIndex = 0; perfRunIndex < 5; ++perfRunIndex)
         var random = new Random();
         var stopwatch = Stopwatch.StartNew();
         for (int i = 0; i < 1000000; ++i)
            double randomDouble = random.NextDouble();
         elapsedMillisecondsBestOf5 = Math.Min(
            elapsedMillisecondsBestOf5, stopwatch.ElapsedMilliseconds);
      return elapsedMillisecondsBestOf5;

Code Output

C# String Formatting Performance
Milliseconds Per 1 Million Iterations - Best Of 5
            $"{value:formatString}": 419 ms
 string.Format(formatString, value): 419 ms
       value.ToString(formatString): 264 ms


Custom Numeric Format Strings []

Qt Charts BarChart Example []

How do I check if a string is a number (float)?

You can generalize the exception technique in a useful way by returning more useful values than True and False. For example this function puts quotes round strings but leaves numbers alone. Which is just what I needed for a quick and dirty filter to make some variable definitions for R.

import sys

def fix_quotes(s):
        return s
    except ValueError:
        return '"{0}"'.format(s)

for line in sys.stdin:
    input = line.split()
    print input[0], '<- c(', ','.join(fix_quotes(c) for c in input[1:]), ')'

When should I use a struct rather than a class in C#?

Briefly, use struct if:

  1. your object properties/fields do not need to be changed. I mean you just want to give them an initial value and then read them.

  2. properties and fields in your object are value type and they are not so large.

If that's the case, you can take advantage of structs for a better performance and optimized memory allocation as they use only stacks rather than both stacks and heaps (in classes)

javascript regex - look behind alternative?

If you can look ahead but back, you could reverse the string first and then do a lookahead. Some more work will need to be done, of course.

How to do a timer in Angular 5

You can simply use setInterval to create such timer in Angular, Use this Code for timer -

timeLeft: number = 60;

startTimer() {
    this.interval = setInterval(() => {
      if(this.timeLeft > 0) {
      } else {
        this.timeLeft = 60;

  pauseTimer() {

<button (click)='startTimer()'>Start Timer</button>
<button (click)='pauseTimer()'>Pause</button>

<p>{{timeLeft}} Seconds Left....</p>

Working Example

Another way using Observable timer like below -

import { timer } from 'rxjs';

observableTimer() {
    const source = timer(1000, 2000);
    const abc = source.subscribe(val => {
      console.log(val, '-');
      this.subscribeTimer = this.timeLeft - val;

<p (click)="observableTimer()">Start Observable timer</p> {{subscribeTimer}}

Working Example

For more information read here

How to mkdir only if a directory does not already exist?

This is a simple function (Bash shell) which lets you create a directory if it doesn't exist.

# Create a directory if it doesn't exist
createDirectory() {
    if [ ! -d $1 ]
        mkdir -p $1

You can call the above function as:

createDirectory /tmp/fooDir/BarDir

The above creates fooDir and BarDir if they don't exist. Note the "-p" option in the mkdir command which creates directories recursively.

How to create a function in a cshtml template?

If your method doesn't have to return html and has to do something else then you can use a lambda instead of helper method in Razor

    ViewBag.Title = "Index";
    Layout = "~/Views/Shared/_Layout.cshtml";

    Func<int,int,int> Sum = (a, b) => a + b;



How can I convert an HTML element to a canvas element?

There is a library that try to do what you say.

See this examples and get the code

Reads the DOM, from the html and render it to a canvas, fail on some, but in general works.

"Specified argument was out of the range of valid values"

I was also getting same issue as i tried using value 0 in non-based indexing,i.e starting with 1, not with zero

Twitter Bootstrap modal: How to remove Slide down effect

just remove 'fade' class from modal class

class="modal fade bs-example-modal-lg"


class="modal bs-example-modal-lg"

What is makeinfo, and how do I get it?

In (at least) Ubuntu when using bash, it tells you what package you need to install if you type in a command and its not found in your path. My terminal says you need to install 'texinfo' package.

sudo apt-get install texinfo

How can I give access to a private GitHub repository?

If you are the owner it is simple:

  • Go to your repo and click the Settings button.
  • In the left menu click Collaborators
  • Then Add their name.

Then collaborator should visit this example repo link

Source: Github Docs.

How to set a variable inside a loop for /F

Try this:

setlocal EnableDelayedExpansion


for /F "tokens=*" %%a in ('type %FileName%') do (
    set z=%%a
    echo !z!
    echo %%a

JavaScript - Get Browser Height

Try using jquery:

window_size = $(window).height();

How to get the list of all printers in computer

Look at the static System.Drawing.Printing.PrinterSettings.InstalledPrinters property.

It is a list of the names of all installed printers on the system.

Code for best fit straight line of a scatter plot in python

A one-line version of this excellent answer to plot the line of best fit is:

plt.plot(np.unique(x), np.poly1d(np.polyfit(x, y, 1))(np.unique(x)))

Using np.unique(x) instead of x handles the case where x isn't sorted or has duplicate values.

What is the boundary in multipart/form-data?

Is the ??? free to be defined by the user?


or is it supplied by the HTML?

No. HTML has nothing to do with that. Read below.

Is it possible for me to define the ??? as abcdefg?


If you want to send the following data to the web server:

name = John
age = 12

using application/x-www-form-urlencoded would be like this:


As you can see, the server knows that parameters are separated by an ampersand &. If & is required for a parameter value then it must be encoded.

So how does the server know where a parameter value starts and ends when it receives an HTTP request using multipart/form-data?

Using the boundary, similar to &.

For example:

Content-Disposition: form-data; name="name"

Content-Disposition: form-data; name="age"


In that case, the boundary value is XXX. You specify it in the Content-Type header so that the server knows how to split the data it receives.

So you need to:

  • Use a value that won't appear in the HTTP data sent to the server.

  • Be consistent and use the same value everywhere in the request message.

Create a string of variable length, filled with a repeated character

Unfortunately although the Array.join approach mentioned here is terse, it is about 10X slower than a string-concatenation-based implementation. It performs especially badly on large strings. See below for full performance details.

On Firefox, Chrome, Node.js MacOS, Node.js Ubuntu, and Safari, the fastest implementation I tested was:

function repeatChar(count, ch) {
    if (count == 0) {
        return "";
    var count2 = count / 2;
    var result = ch;

    // double the input until it is long enough.
    while (result.length <= count2) {
        result += result;
    // use substring to hit the precise length target without
    // using extra memory
    return result + result.substring(0, count - result.length);

This is verbose, so if you want a terse implementation you could go with the naive approach; it still performs betweeb 2X to 10X better than the Array.join approach, and is also faster than the doubling implementation for small inputs. Code:

// naive approach: simply add the letters one by one
function repeatChar(count, ch) {
    var txt = "";
    for (var i = 0; i < count; i++) {
        txt += ch;
    return txt;

Further information:

Loading another html page from javascript

Yes. In the javascript code:

window.location.href = "";

How do I get a background location update every n minutes in my iOS application?

Attached is a Swift solution based in:

Define App registers for location updates in the info.plist

Keep the locationManager running all the time

Switch kCLLocationAccuracy between BestForNavigation (for 5 secs to get the location) and ThreeKilometers for the rest of the wait period to avoid battery drainage

This example updates location every 1 min in Foreground and every 15 mins in Background.

The example works fine with Xcode 6 Beta 6, running in a iOS 7 device.

In the App Delegate (mapView is an Optional pointing to the mapView Controller)

func applicationDidBecomeActive(application: UIApplication!) {
    if appLaunched! == false { // Reference to mapView used to limit one location update per timer cycle
        appLaunched = true
        var appDelegate = UIApplication.sharedApplication().delegate as AppDelegate
        var window = appDelegate.window
        var tabBar = window?.rootViewController as UITabBarController
        var navCon = tabBar.viewControllers[0] as UINavigationController
        mapView = navCon.topViewController as? MapViewController

func applicationDidEnterBackground(application: UIApplication!) {
    self.startInitialPeriodWithTimeInterval(15 * 60.0)

func startInitialPeriodWithTimeInterval(timeInterval: NSTimeInterval) {
    timer?.invalidate() // reset timer
    locationManager?.desiredAccuracy = kCLLocationAccuracyBestForNavigation
    timer = NSTimer.scheduledTimerWithTimeInterval(5.0, target: self, selector: Selector("getFirstLocationUpdate:"), userInfo: timeInterval, repeats: false)

func getFirstLocationUpdate(sender: NSTimer) {
    let timeInterval = sender.userInfo as Double
    mapView?.canReportLocation = true
    timer = NSTimer.scheduledTimerWithTimeInterval(timeInterval, target: self, selector: Selector("waitForTimer:"), userInfo: timeInterval, repeats: true)

func waitForTimer(sender: NSTimer) {
    let time = sender.userInfo as Double
    locationManager?.desiredAccuracy = kCLLocationAccuracyBestForNavigation
    finalTimer = NSTimer.scheduledTimerWithTimeInterval(5.0, target: self, selector: Selector("getLocationUpdate"), userInfo: nil, repeats: false)

func getLocationUpdate() {
    mapView?.canReportLocation = true

In the mapView (locationManager points to the object in the AppDelegate)

override func viewDidLoad() {
    var appDelegate = UIApplication.sharedApplication().delegate! as AppDelegate
    locationManager = appDelegate.locationManager!
    locationManager.delegate = self
    canReportLocation = true

  func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
        if canReportLocation! {
            canReportLocation = false
            locationManager.desiredAccuracy = kCLLocationAccuracyThreeKilometers
        } else {
            //println("Ignore location update")

How can I reference a dll in the GAC from Visual Studio?

May be it's too late to answer, but i found a very simple way to do this(without a hack).

  1. Put your dll in GAC (for 3.5 Drag Drop inside "C:\Windows\assembly\")
  2. GoTo Projects --> Properties
  3. Click Reference Path (for 3.5 it's "C:\Windows\assembly\")
  4. and Build

Hope it helps

Using margin:auto to vertically-align a div

I know the question is from 2012, but I found the easiest way ever, and I wanted to share.


<div id="parent">
     <div id="child">Content here</div>

and CSS:

     height: 100%;
     display: table;
#child {
     display: table-cell;
     vertical-align: middle; 

React: how to update state.item[1] in state using setState?

Found this surprisingly hard and none of the ES6 spread magic seemed to work as expected. Was using a structure like this to get rendered element properties for layout purposes.

found using the update method from immutability-helper to be the most straight forward one in this simplified example:

constructor(props) {
    this.state = { values: [] }
    this.updateContainerState = this.updateContainerState.bind(this)

updateContainerState(index, value) {
    this.setState((state) => update(state, { values: { [index]: { $set: value } } }))

as adapted from

of the to be updated array member is a more nested complex object use the appropriate deep copy method based on complexity.

There are surely better ways to handle layout parameters, but this is about how to handle arrays. The relevant values for each child element could also be computed outside of them, but I found it more convenient to pass containerState down, so they childs can fetch properties at will and Update the parent state array at their given index.

import React from 'react'
import update from 'immutability-helper'
import { ContainerElement } from './'
import ChildComponent from './child-component'
export default class ContainerComponent extends React.Component {
  constructor(props) {
    this.state = { values: [] }
    this.updateContainerState = this.updateContainerState.bind(this)

  updateContainerState(index, value) {
    this.setState((state) => update(state, { values: { [index]: { $set: value } } }))

  // ...

  render() {
    let index = 0
    return (

Making macOS Installer Packages which are Developer ID ready

Our example project has two build targets: and We make a component package for each and combine them into a product archive.

A component package contains payload to be installed by the OS X Installer. Although a component package can be installed on its own, it is typically incorporated into a product archive.

Our tools: pkgbuild, productbuild, and pkgutil

After a successful "Build and Archive" open $BUILT_PRODUCTS_DIR in the Terminal.

$ cd ~/Library/Developer/Xcode/DerivedData/.../InstallationBuildProductsLocation
$ pkgbuild --analyze --root ./ HelloWorldAppComponents.plist
$ pkgbuild --analyze --root ./ HelperAppComponents.plist

This give us the component-plist, you find the value description in the "Component Property List" section. pkgbuild -root generates the component packages, if you don't need to change any of the default properties you can omit the --component-plist parameter in the following command.

productbuild --synthesize results in a Distribution Definition.

$ pkgbuild --root ./ \
    --component-plist HelloWorldAppComponents.plist \
$ pkgbuild --root ./ \
    --component-plist HelperAppComponents.plist \
$ productbuild --synthesize \
    --package HelloWorld.pkg --package Helper.pkg \

In the Distribution.xml you can change things like title, background, welcome, readme, license, and so on. You turn your component packages and distribution definition with this command into a product archive:

$ productbuild --distribution ./Distribution.xml \
    --package-path . \

I recommend to take a look at iTunes Installers Distribution.xml to see what is possible. You can extract "Install iTunes.pkg" with:

$ pkgutil --expand "Install iTunes.pkg" "Install iTunes"

Lets put it together

I usually have a folder named Package in my project which includes things like Distribution.xml, component-plists, resources and scripts.

Add a Run Script Build Phase named "Generate Package", which is set to Run script only when installing:

VERSION=$(defaults read "${BUILT_PRODUCTS_DIR}/${FULL_PRODUCT_NAME}/Contents/Info" CFBundleVersion)

PACKAGE_NAME=`echo "$PRODUCT_NAME" | sed "s/ /_/g"`

pkgbuild --root "${INSTALL_ROOT}" \
    --component-plist "./Package/HelloWorldAppComponents.plist" \
    --scripts "./Package/Scripts" \
    --identifier "com.test.pkg.HelloWorld" \
    --version "$VERSION" \
    --install-location "/" \
pkgbuild --root "${BUILT_PRODUCTS_DIR}/" \
    --component-plist "./Package/HelperAppComponents.plist" \
    --identifier "com.test.pkg.Helper" \
    --version "$VERSION" \
    --install-location "/" \
productbuild --distribution "./Package/Distribution.xml"  \
    --package-path "${BUILT_PRODUCTS_DIR}" \
    --resources "./Package/Resources" \

pkgutil --expand "${TMP1_ARCHIVE}" "${TMP2_ARCHIVE}"
# Patches and Workarounds

pkgutil --flatten "${TMP2_ARCHIVE}" "${TMP3_ARCHIVE}"

productsign --sign "Developer ID Installer: John Doe" \

If you don't have to change the package after it's generated with productbuild you could get rid of the pkgutil --expand and pkgutil --flatten steps. Also you could use the --sign paramenter on productbuild instead of running productsign.

Sign an OS X Installer

Packages are signed with the Developer ID Installer certificate which you can download from Developer Certificate Utility.

They signing is done with the --sign "Developer ID Installer: John Doe" parameter of pkgbuild, productbuild or productsign.

Note that if you are going to create a signed product archive using productbuild, there is no reason to sign the component packages.

Developer Certificate Utility

All the way: Copy Package into Xcode Archive

To copy something into the Xcode Archive we can't use the Run Script Build Phase. For this we need to use a Scheme Action.

Edit Scheme and expand Archive. Then click post-actions and add a New Run Script Action:

In Xcode 6:


PACKAGE_NAME=`echo "$PRODUCT_NAME" | sed "s/ /_/g"`

if [ -f "${PKG}" ]; then
    mkdir "${PACKAGES}"
    cp -r "${PKG}" "${PACKAGES}"

In Xcode 5, use this value for PKG instead:


In case your version control doesn't store Xcode Scheme information I suggest to add this as shell script to your project so you can simple restore the action by dragging the script from the workspace into the post-action.


There are two different kinds of scripting: JavaScript in Distribution Definition Files and Shell Scripts.

The best documentation about Shell Scripts I found in WhiteBox - PackageMaker How-to, but read this with caution because it refers to the old package format.

Apple Silicon

In order for the package to run as arm64, the Distribution file has to specify in its hostArchitectures section that it supports arm64 in addition to x86_64:

<options hostArchitectures="arm64,x86_64" />

Additional Reading

Known Issues and Workarounds

Destination Select Pane

The user is presented with the destination select option with only a single choice - "Install for all users of this computer". The option appears visually selected, but the user needs to click on it in order to proceed with the installation, causing some confusion.

Example showing the installer bug

Apples Documentation recommends to use <domains enable_anywhere ... /> but this triggers the new more buggy Destination Select Pane which Apple doesn't use in any of their Packages.

Using the deprecate <options rootVolumeOnly="true" /> give you the old Destination Select Pane. Example showing old Destination Select Pane

You want to install items into the current user’s home folder.

Short answer: DO NOT TRY IT!

Long answer: REALLY; DO NOT TRY IT! Read Installer Problems and Solutions. You know what I did even after reading this? I was stupid enough to try it. Telling myself I'm sure that they fixed the issues in 10.7 or 10.8.

First of all I saw from time to time the above mentioned Destination Select Pane Bug. That should have stopped me, but I ignored it. If you don't want to spend the week after you released your software answering support e-mails that they have to click once the nice blue selection DO NOT use this.

You are now thinking that your users are smart enough to figure the panel out, aren't you? Well here is another thing about home folder installation, THEY DON'T WORK!

I tested it for two weeks on around 10 different machines with different OS versions and what not, and it never failed. So I shipped it. Within an hour of the release I heart back from users who just couldn't install it. The logs hinted to permission issues you are not gonna be able to fix.

So let's repeat it one more time: We do not use the Installer for home folder installations!

RTFD for Welcome, Read-me, License and Conclusion is not accepted by productbuild.

Installer supported since the beginning RTFD files to make pretty Welcome screens with images, but productbuild doesn't accept them.

Workarounds: Use a dummy rtf file and replace it in the package by after productbuild is done.

Note: You can also have Retina images inside the RTFD file. Use multi-image tiff files for this: tiffutil -cat Welcome.tif Welcome_2x.tif -out FinalWelcome.tif. More details.

Starting an application when the installation is done with a BundlePostInstallScriptPath script:



if [ "${COMMAND_LINE_INSTALL}" = "" ]
    /bin/launchctl asuser "${LOGGED_IN_USER_ID}" /usr/bin/open -g PATH_OR_BUNDLE_ID

exit 0

It is important to run the app as logged in user, not as the installer user. This is done with launchctl asuser uid path. Also we only run it when it is not a command line installation, done with installer tool or Apple Remote Desktop.

Debug JavaScript in Eclipse

I'm not a 100% sure but I think Aptana let's you do that.

Get current date in milliseconds

NSTimeInterval milisecondedDate = ([[NSDate date] timeIntervalSince1970] * 1000);

Git commit -a "untracked files"?

As the name suggests 'untracked files' are the files which are not being tracked by git. They are not in your staging area, and were not part of any previous commits. If you want them to be versioned (or to be managed by git) you can do so by telling 'git' by using 'git add'. Check this chapter Recording Changes to the Repository in the Progit book which uses a nice visual to provide a good explanation about recording changes to git repo and also explaining the terms 'tracked' and 'untracked'.


Visual Studio defines _DEBUG when you specify the /MTd or /MDd option, NDEBUG disables standard-C assertions. Use them when appropriate, ie _DEBUG if you want your debugging code to be consistent with the MS CRT debugging techniques and NDEBUG if you want to be consistent with assert().

If you define your own debugging macros (and you don't hack the compiler or C runtime), avoid starting names with an underscore, as these are reserved.

Why is January month 0 in Java Calendar?

I'd say laziness. Arrays start at 0 (everyone knows that); the months of the year are an array, which leads me to believe that some engineer at Sun just didn't bother to put this one little nicety into the Java code.

Get number of digits with JavaScript

var i = 1;
while( ( n /= 10 ) >= 1 ){ i++ }

23432          i = 1
 2343.2        i = 2
  234.32       i = 3
   23.432      i = 4
    2.3432     i = 5

Cycles in family tree software

Your family tree should use directed relations. This way you won't have a cycle.

Bootstrap's JavaScript requires jQuery version 1.9.1 or higher

Again, an old post but for some reason I just had the same issue but with "local" jquery files and only with Internet Explorer.

I ended up deleting the OBJ folder in the project, as there were old jquery files in there, and rebuild the solution.

Callback when CSS3 transition finishes

Another option would be to use the jQuery Transit Framework to handle your CSS3 transitions. The transitions/effects perform well on mobile devices and you don't have to add a single line of messy CSS3 transitions in your CSS file in order to do the animation effects.

Here is an example that will transition an element's opacity to 0 when you click on it and will be removed once the transition is complete:

$("#element").click( function () {
    $('#element').transition({ opacity: 0 }, function () { $(this).remove(); });

JS Fiddle Demo

Styling mat-select in Angular Material

Put your class name on the mat-form-field element. This works for all inputs.

PersistentObjectException: detached entity passed to persist thrown by JPA and Hibernate

Resolved by saving dependent object before the next.

This was happened to me because I was not setting Id (which was not auto generated). and trying to save with relation @ManytoOne

How do I determine k when using k-means clustering?

Yes, you can find the best number of clusters using Elbow method, but I found it troublesome to find the value of clusters from elbow graph using script. You can observe the elbow graph and find the elbow point yourself, but it was lot of work finding it from script.

So another option is to use Silhouette Method to find it. The result from Silhouette completely comply with result from Elbow method in R.

Here`s what I did.

#Dataset for Clustering
n = 150
g = 6 
d <- data.frame(x = unlist(lapply(1:g, function(i) rnorm(n/g, runif(1)*i^2))), 
                y = unlist(lapply(1:g, function(i) rnorm(n/g, runif(1)*i^2))))
#Plot 3X2 plots

#Plot the original dataset
plot(mydata$x,mydata$y,main="Original Dataset")

#Scree plot to deterine the number of clusters
wss <- (nrow(mydata)-1)*sum(apply(mydata,2,var))
  for (i in 2:15) {
    wss[i] <- sum(kmeans(mydata,centers=i)$withinss)
plot(1:15, wss, type="b", xlab="Number of Clusters",ylab="Within groups sum of squares")

# Ward Hierarchical Clustering
d <- dist(mydata, method = "euclidean") # distance matrix
fit <- hclust(d, method="ward") 
plot(fit) # display dendogram
groups <- cutree(fit, k=5) # cut tree into 5 clusters
# draw dendogram with red borders around the 5 clusters 
rect.hclust(fit, k=5, border="red")

#Silhouette analysis for determining the number of clusters
asw <- numeric(20)
for (k in 2:20)
  asw[[k]] <- pam(mydata, k) $ silinfo $ avg.width <- which.max(asw)

cat("silhouette-optimal number of clusters:",, "\n")

# K-Means Cluster Analysis
fit <- kmeans(mydata,
# get cluster means 
# append cluster assignment
mydata <- data.frame(mydata, clusterid=fit$cluster)
plot(mydata$x,mydata$y, col = fit$cluster, main="K-means Clustering results")

Hope it helps!!

Adding elements to a C# array

You can use this snippet:

static void Main(string[] args)

        Console.WriteLine("Enter number:");
        int fnum = 0;
        bool chek = Int32.TryParse(Console.ReadLine(),out fnum);            

        Console.WriteLine("Enter number:");
        int snum = 0;
        chek = Int32.TryParse(Console.ReadLine(),out snum);

        Console.WriteLine("Enter number:");
        int thnum = 0;
        chek = Int32.TryParse(Console.ReadLine(),out thnum);

        int[] arr = AddToArr(fnum,snum,thnum);

        IOrderedEnumerable<int> oarr = arr.OrderBy(delegate(int s)
            return s;

        Console.WriteLine("Here your result:");

        oarr.ToList().FindAll(delegate(int num) {


            return num > 0;



public static int[] AddToArr(params int[] arr) {

    return arr;

I hope this will help to you, just change the type

Field 'id' doesn't have a default value?

To detect run:

select @@sql_mode
-- It will give something like:

To fix, run:

set global sql_mode = ''

How to change value of a request parameter in laravel

Use merge():

    'user_id' => $modified_user_id_here,

Simple! No need to transfer the entire $request->all() to another variable.

How to select element using XPATH syntax on Selenium for Python?


<div id='a'>
    <a class='click'>abc</a>

You could use the XPATH as :



<a class="click">abc</a>

That said your Python code should be as :


Stop node.js program from command line

you can type .exit to quit node js REPL

FtpWebRequest Download File

FYI, Microsoft recommends not using FtpWebRequest for new development:

We don't recommend that you use the FtpWebRequest class for new development. For more information and alternatives to FtpWebRequest, see WebRequest shouldn't be used on GitHub.

The GitHub link directs to this SO page which contains a list of third-party FTP libraries, such as FluentFTP.

Execute external program


public class Code {
  public static void main(String[] args) throws Exception {
    ProcessBuilder builder = new ProcessBuilder("ls", "-ltr");
    Process process = builder.start();

    StringBuilder out = new StringBuilder();
    try (BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()))) {
        String line = null;
      while ((line = reader.readLine()) != null) {

Try online

Resize background image in div using css

With the background-size property in those browsers which support this very new feature of CSS.

Laravel check if collection is empty

To determine if there are any results you can do any of the following:

if ($mentor->first()) { } 
if (!$mentor->isEmpty()) { }
if ($mentor->count()) { }
if (count($mentor)) { }
if ($mentor->isNotEmpty()) { }

Notes / References




count($mentors) works because the Collection implements Countable and an internal count() method:


So what you can do is :

if (!$mentors->intern->employee->isEmpty()) { }

Restoring Nuget References?

You need to Enable NuGet package restore at the VS solution level for the restore missing package to work.

enter image description here

Highcharts - redraw() vs. new Highcharts.chart

@RobinL as mentioned in previous comments, you can use chart.series[n].setData(). First you need to make sure you’ve assigned a chart instance to the chart variable, that way it adopts all the properties and methods you need to access and manipulate the chart.

I’ve also used the second parameter of setData() and had it false, to prevent automatic rendering of the chart. This was because I have multiple data series, so I’ll rather update each of them, with render=false, and then running chart.redraw(). This multiplied performance (I’m having 10,000-100,000 data points and refreshing the data set every 50 milliseconds).

Display all post meta keys and meta values of the same post ID in wordpress

I use it in form of a meta box. Here is a function that dumps values of all the meta data for post.

    function dump_all_meta(){

        echo "<h3>All Post Meta</h3>";

        // Get all the data.

        foreach( $getPostCustom as $name=>$value ) {

            echo "<strong>".$name."</strong>"."  =>  ";

            foreach($getPostCustom as $name=>$value) {

        echo "<strong>".$name."</strong>"."  =>  ";

        foreach($value as $nameAr=>$valueAr) {
                echo "<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;";
                echo $nameAr."  =>  ";
                echo var_dump($valueAr);

        echo "<br /><br />";

    } // Callback funtion ended.

Hope it helps. You can use it inside a meta box or at the front-end.

How do I use extern to share variables between source files?

Using extern is only of relevance when the program you're building consists of multiple source files linked together, where some of the variables defined, for example, in source file file1.c need to be referenced in other source files, such as file2.c.

It is important to understand the difference between defining a variable and declaring a variable:

  • A variable is declared when the compiler is informed that a variable exists (and this is its type); it does not allocate the storage for the variable at that point.

  • A variable is defined when the compiler allocates the storage for the variable.

You may declare a variable multiple times (though once is sufficient); you may only define it once within a given scope. A variable definition is also a declaration, but not all variable declarations are definitions.

Best way to declare and define global variables

The clean, reliable way to declare and define global variables is to use a header file to contain an extern declaration of the variable.

The header is included by the one source file that defines the variable and by all the source files that reference the variable. For each program, one source file (and only one source file) defines the variable. Similarly, one header file (and only one header file) should declare the variable. The header file is crucial; it enables cross-checking between independent TUs (translation units — think source files) and ensures consistency.

Although there are other ways of doing it, this method is simple and reliable. It is demonstrated by file3.h, file1.c and file2.c:


extern int global_variable;  /* Declaration of the variable */


#include "file3.h"  /* Declaration made available here */
#include "prog1.h"  /* Function declarations */

/* Variable defined here */
int global_variable = 37;    /* Definition checked against declaration */

int increment(void) { return global_variable++; }


#include "file3.h"
#include "prog1.h"
#include <stdio.h>

void use_it(void)
    printf("Global variable: %d\n", global_variable++);

That's the best way to declare and define global variables.

The next two files complete the source for prog1:

The complete programs shown use functions, so function declarations have crept in. Both C99 and C11 require functions to be declared or defined before they are used (whereas C90 did not, for good reasons). I use the keyword extern in front of function declarations in headers for consistency — to match the extern in front of variable declarations in headers. Many people prefer not to use extern in front of function declarations; the compiler doesn't care — and ultimately, neither do I as long as you're consistent, at least within a source file.


extern void use_it(void);
extern int increment(void);


#include "file3.h"
#include "prog1.h"
#include <stdio.h>

int main(void)
    global_variable += 19;
    printf("Increment: %d\n", increment());
    return 0;
  • prog1 uses prog1.c, file1.c, file2.c, file3.h and prog1.h.

The file is a makefile for prog1 only. It will work with most versions of make produced since about the turn of the millennium. It is not tied specifically to GNU Make.

# Minimal makefile for prog1

PROGRAM = prog1
FILES.c = prog1.c file1.c file2.c
FILES.h = prog1.h file3.h
FILES.o = ${FILES.c:.c=.o}

CC      = gcc
SFLAGS  = -std=c11
GFLAGS  = -g
WFLAG1  = -Wall
WFLAG2  = -Wextra
WFLAG3  = -Werror
WFLAG4  = -Wstrict-prototypes
WFLAG5  = -Wmissing-prototypes
UFLAGS  = # Set on command line only


all:    ${PROGRAM}

    ${CC} -o $@ ${CFLAGS} ${FILES.o} ${LDFLAGS} ${LDLIBS}

prog1.o: ${FILES.h}
file1.o: ${FILES.h}
file2.o: ${FILES.h}

# If it exists, prog1.dSYM is a directory on macOS
DEBRIS = a.out core *~ *.dSYM
RM_FR  = rm -fr

    ${RM_FR} ${FILES.o} ${PROGRAM} ${DEBRIS}


Rules to be broken by experts only, and only with good reason:

  • A header file only contains extern declarations of variables — never static or unqualified variable definitions.

  • For any given variable, only one header file declares it (SPOT — Single Point of Truth).

  • A source file never contains extern declarations of variables — source files always include the (sole) header that declares them.

  • For any given variable, exactly one source file defines the variable, preferably initializing it too. (Although there is no need to initialize explicitly to zero, it does no harm and can do some good, because there can be only one initialized definition of a particular global variable in a program).

  • The source file that defines the variable also includes the header to ensure that the definition and the declaration are consistent.

  • A function should never need to declare a variable using extern.

  • Avoid global variables whenever possible — use functions instead.

The source code and text of this answer are available in my SOQ (Stack Overflow Questions) repository on GitHub in the src/so-0143-3204 sub-directory.

If you're not an experienced C programmer, you could (and perhaps should) stop reading here.

Not so good way to define global variables

With some (indeed, many) C compilers, you can get away with what's called a 'common' definition of a variable too. 'Common', here, refers to a technique used in Fortran for sharing variables between source files, using a (possibly named) COMMON block. What happens here is that each of a number of files provides a tentative definition of the variable. As long as no more than one file provides an initialized definition, then the various files end up sharing a common single definition of the variable:


#include "prog2.h"

long l;   /* Do not do this in portable code */

void inc(void) { l++; }


#include "prog2.h"

long l;   /* Do not do this in portable code */

void dec(void) { l--; }


#include "prog2.h"
#include <stdio.h>

long l = 9;   /* Do not do this in portable code */

void put(void) { printf("l = %ld\n", l); }

This technique does not conform to the letter of the C standard and the 'one definition rule' — it is officially undefined behaviour:

J.2 Undefined behavior

An identifier with external linkage is used, but in the program there does not exist exactly one external definition for the identifier, or the identifier is not used and there exist multiple external definitions for the identifier (6.9).

§6.9 External definitions ¶5

An external definition is an external declaration that is also a definition of a function (other than an inline definition) or an object. If an identifier declared with external linkage is used in an expression (other than as part of the operand of a sizeof or _Alignof operator whose result is an integer constant), somewhere in the entire program there shall be exactly one external definition for the identifier; otherwise, there shall be no more than one.161)

161) Thus, if an identifier declared with external linkage is not used in an expression, there need be no external definition for it.

However, the C standard also lists it in informative Annex J as one of the Common extensions.

J.5.11 Multiple external definitions

There may be more than one external definition for the identifier of an object, with or without the explicit use of the keyword extern; if the definitions disagree, or more than one is initialized, the behavior is undefined (6.9.2).

Because this technique is not always supported, it is best to avoid using it, especially if your code needs to be portable. Using this technique, you can also end up with unintentional type punning.

If one of the files above declared l as a double instead of as a long, C's type-unsafe linkers probably would not spot the mismatch. If you're on a machine with 64-bit long and double, you'd not even get a warning; on a machine with 32-bit long and 64-bit double, you'd probably get a warning about the different sizes — the linker would use the largest size, exactly as a Fortran program would take the largest size of any common blocks.

Note that GCC 10.1.0, which was released on 2020-05-07, changes the default compilation options to use -fno-common, which means that by default, the code above no longer links unless you override the default with -fcommon (or use attributes, etc — see the link).

The next two files complete the source for prog2:


extern void dec(void);
extern void put(void);
extern void inc(void);


#include "prog2.h"
#include <stdio.h>

int main(void)
  • prog2 uses prog2.c, file10.c, file11.c, file12.c, prog2.h.


As noted in comments here, and as stated in my answer to a similar question, using multiple definitions for a global variable leads to undefined behaviour (J.2; §6.9), which is the standard's way of saying "anything could happen". One of the things that can happen is that the program behaves as you expect; and J.5.11 says, approximately, "you might be lucky more often than you deserve". But a program that relies on multiple definitions of an extern variable — with or without the explicit 'extern' keyword — is not a strictly conforming program and not guaranteed to work everywhere. Equivalently: it contains a bug which may or may not show itself.

Violating the guidelines

There are, of course, many ways in which these guidelines can be broken. Occasionally, there may be a good reason to break the guidelines, but such occasions are extremely unusual.


int some_var;    /* Do not do this in a header!!! */

Note 1: if the header defines the variable without the extern keyword, then each file that includes the header creates a tentative definition of the variable. As noted previously, this will often work, but the C standard does not guarantee that it will work.


int some_var = 13;    /* Only one source file in a program can use this */

Note 2: if the header defines and initializes the variable, then only one source file in a given program can use the header. Since headers are primarily for sharing information, it is a bit silly to create one that can only be used once.


static int hidden_global = 3;   /* Each source file gets its own copy  */

Note 3: if the header defines a static variable (with or without initialization), then each source file ends up with its own private version of the 'global' variable.

If the variable is actually a complex array, for example, this can lead to extreme duplication of code. It can, very occasionally, be a sensible way to achieve some effect, but that is very unusual.


Use the header technique I showed first. It works reliably and everywhere. Note, in particular, that the header declaring the global_variable is included in every file that uses it — including the one that defines it. This ensures that everything is self-consistent.

Similar concerns arise with declaring and defining functions — analogous rules apply. But the question was about variables specifically, so I've kept the answer to variables only.

End of Original Answer

If you're not an experienced C programmer, you probably should stop reading here.

Late Major Addition

Avoiding Code Duplication

One concern that is sometimes (and legitimately) raised about the 'declarations in headers, definitions in source' mechanism described here is that there are two files to be kept synchronized — the header and the source. This is usually followed up with an observation that a macro can be used so that the header serves double duty — normally declaring the variables, but when a specific macro is set before the header is included, it defines the variables instead.

Another concern can be that the variables need to be defined in each of a number of 'main programs'. This is normally a spurious concern; you can simply introduce a C source file to define the variables and link the object file produced with each of the programs.

A typical scheme works like this, using the original global variable illustrated in file3.h:


#define EXTERN /* nothing */
#define EXTERN extern

EXTERN int global_variable;


#include "file3a.h"  /* Variable defined - but not initialized */
#include "prog3.h"

int increment(void) { return global_variable++; }


#include "file3a.h"
#include "prog3.h"
#include <stdio.h>

void use_it(void)
    printf("Global variable: %d\n", global_variable++);

The next two files complete the source for prog3:


extern void use_it(void);
extern int increment(void);


#include "file3a.h"
#include "prog3.h"
#include <stdio.h>

int main(void)
    global_variable += 19;
    printf("Increment: %d\n", increment());
    return 0;
  • prog3 uses prog3.c, file1a.c, file2a.c, file3a.h, prog3.h.

Variable initialization

The problem with this scheme as shown is that it does not provide for initialization of the global variable. With C99 or C11 and variable argument lists for macros, you could define a macro to support initialization too. (With C89 and no support for variable argument lists in macros, there is no easy way to handle arbitrarily long initializers.)


#define EXTERN                  /* nothing */
#define INITIALIZER(...)        = __VA_ARGS__
#define EXTERN                  extern
#define INITIALIZER(...)        /* nothing */

EXTERN int global_variable INITIALIZER(37);
EXTERN struct { int a; int b; } oddball_struct INITIALIZER({ 41, 43 });

Reverse contents of #if and #else blocks, fixing bug identified by Denis Kniazhev


#include "file3b.h"  /* Variables now defined and initialized */
#include "prog4.h"

int increment(void) { return global_variable++; }
int oddball_value(void) { return oddball_struct.a + oddball_struct.b; }


#include "file3b.h"
#include "prog4.h"
#include <stdio.h>

void use_them(void)
    printf("Global variable: %d\n", global_variable++);
    oddball_struct.a += global_variable;
    oddball_struct.b -= global_variable / 2;

Clearly, the code for the oddball structure is not what you'd normally write, but it illustrates the point. The first argument to the second invocation of INITIALIZER is { 41 and the remaining argument (singular in this example) is 43 }. Without C99 or similar support for variable argument lists for macros, initializers that need to contain commas are very problematic.

Correct header file3b.h included (instead of fileba.h) per Denis Kniazhev

The next two files complete the source for prog4:


extern int increment(void);
extern int oddball_value(void);
extern void use_them(void);


#include "file3b.h"
#include "prog4.h"
#include <stdio.h>

int main(void)
    global_variable += 19;
    printf("Increment: %d\n", increment());
    printf("Oddball:   %d\n", oddball_value());
    return 0;
  • prog4 uses prog4.c, file1b.c, file2b.c, prog4.h, file3b.h.

Header Guards

Any header should be protected against reinclusion, so that type definitions (enum, struct or union types, or typedefs generally) do not cause problems. The standard technique is to wrap the body of the header in a header guard such as:


...contents of header...

#endif /* FILE3B_H_INCLUDED */

The header might be included twice indirectly. For example, if file4b.h includes file3b.h for a type definition that isn't shown, and file1b.c needs to use both header file4b.h and file3b.h, then you have some more tricky issues to resolve. Clearly, you might revise the header list to include just file4b.h. However, you might not be aware of the internal dependencies — and the code should, ideally, continue to work.

Further, it starts to get tricky because you might include file4b.h before including file3b.h to generate the definitions, but the normal header guards on file3b.h would prevent the header being reincluded.

So, you need to include the body of file3b.h at most once for declarations, and at most once for definitions, but you might need both in a single translation unit (TU — a combination of a source file and the headers it uses).

Multiple inclusion with variable definitions

However, it can be done subject to a not too unreasonable constraint. Let's introduce a new set of file names:

  • external.h for the EXTERN macro definitions, etc.

  • file1c.h to define types (notably, struct oddball, the type of oddball_struct).

  • file2c.h to define or declare the global variables.

  • file3c.c which defines the global variables.

  • file4c.c which simply uses the global variables.

  • file5c.c which shows that you can declare and then define the global variables.

  • file6c.c which shows that you can define and then (attempt to) declare the global variables.

In these examples, file5c.c and file6c.c directly include the header file2c.h several times, but that is the simplest way to show that the mechanism works. It means that if the header was indirectly included twice, it would also be safe.

The restrictions for this to work are:

  1. The header defining or declaring the global variables may not itself define any types.

  2. Immediately before you include a header that should define variables, you define the macro DEFINE_VARIABLES.

  3. The header defining or declaring the variables has stylized contents.


** This header must not contain header guards (like <assert.h> must not).
** Each time it is invoked, it redefines the macros EXTERN, INITIALIZE
** based on whether macro DEFINE_VARIABLES is currently defined.
#undef EXTERN

#define EXTERN              /* nothing */
#define INITIALIZE(...)     = __VA_ARGS__
#define EXTERN              extern
#define INITIALIZE(...)     /* nothing */



struct oddball
    int a;
    int b;

extern void use_them(void);
extern int increment(void);
extern int oddball_value(void);

#endif /* FILE1C_H_INCLUDED */


/* Standard prologue */


#include "external.h"   /* Support macros EXTERN, INITIALIZE */
#include "file1c.h"     /* Type definition for struct oddball */

#if !defined(DEFINE_VARIABLES) || !defined(FILE2C_H_DEFINITIONS)

/* Global variable declarations / definitions */
EXTERN int global_variable INITIALIZE(37);
EXTERN struct oddball oddball_struct INITIALIZE({ 41, 43 });


/* Standard epilogue */

#endif /* FILE2C_H_INCLUDED */


#include "file2c.h"  /* Variables now defined and initialized */

int increment(void) { return global_variable++; }
int oddball_value(void) { return oddball_struct.a + oddball_struct.b; }


#include "file2c.h"
#include <stdio.h>

void use_them(void)
    printf("Global variable: %d\n", global_variable++);
    oddball_struct.a += global_variable;
    oddball_struct.b -= global_variable / 2;


#include "file2c.h"     /* Declare variables */

#include "file2c.h"  /* Variables now defined and initialized */

int increment(void) { return global_variable++; }
int oddball_value(void) { return oddball_struct.a + oddball_struct.b; }


#include "file2c.h"     /* Variables now defined and initialized */

#include "file2c.h"     /* Declare variables */

int increment(void) { return global_variable++; }
int oddball_value(void) { return oddball_struct.a + oddball_struct.b; }

The next source file completes the source (provides a main program) for prog5, prog6 and prog7:


#include "file2c.h"
#include <stdio.h>

int main(void)
    global_variable += 19;
    printf("Increment: %d\n", increment());
    printf("Oddball:   %d\n", oddball_value());
    return 0;
  • prog5 uses prog5.c, file3c.c, file4c.c, file1c.h, file2c.h, external.h.

  • prog6 uses prog5.c, file5c.c, file4c.c, file1c.h, file2c.h, external.h.

  • prog7 uses prog5.c, file6c.c, file4c.c, file1c.h, file2c.h, external.h.

This scheme avoids most problems. You only run into a problem if a header that defines variables (such as file2c.h) is included by another header (say file7c.h) that defines variables. There isn't an easy way around that other than "don't do it".

You can partially work around the problem by revising file2c.h into file2d.h:


/* Standard prologue */


#include "external.h"   /* Support macros EXTERN, INITIALIZE */
#include "file1c.h"     /* Type definition for struct oddball */

#if !defined(DEFINE_VARIABLES) || !defined(FILE2D_H_DEFINITIONS)

/* Global variable declarations / definitions */
EXTERN int global_variable INITIALIZE(37);
EXTERN struct oddball oddball_struct INITIALIZE({ 41, 43 });


/* Standard epilogue */

#endif /* FILE2D_H_INCLUDED */

The issue becomes 'should the header include #undef DEFINE_VARIABLES?' If you omit that from the header and wrap any defining invocation with #define and #undef:

#include "file2c.h"

in the source code (so the headers never alter the value of DEFINE_VARIABLES), then you should be clean. It is just a nuisance to have to remember to write the the extra line. An alternative might be:

#include "externdef.h"


** This header must not contain header guards (like <assert.h> must not).
** Each time it is included, the macro HEADER_DEFINING_VARIABLES should
** be defined with the name (in quotes - or possibly angle brackets) of
** the header to be included that defines variables when the macro
** DEFINE_VARIABLES is defined.  See also: external.h (which uses
** appropriately).
** #define HEADER_DEFINING_VARIABLES "file2c.h"
** #include "externdef.h"


This is getting a tad convoluted, but seems to be secure (using the file2d.h, with no #undef DEFINE_VARIABLES in the file2d.h).


/* Declare variables */
#include "file2d.h"

/* Define variables */
#include "externdef.h"

/* Declare variables - again */
#include "file2d.h"

/* Define variables - again */
#include "externdef.h"

int increment(void) { return global_variable++; }
int oddball_value(void) { return oddball_struct.a + oddball_struct.b; }


/* Standard prologue */


#include "external.h"   /* Support macros EXTERN, INITIALIZE */
#include "file2d.h"     /* struct oddball */

#if !defined(DEFINE_VARIABLES) || !defined(FILE8C_H_DEFINITIONS)

/* Global variable declarations / definitions */
EXTERN struct oddball another INITIALIZE({ 14, 34 });


/* Standard epilogue */

#endif /* FILE8C_H_INCLUDED */


/* Define variables */
#include "externdef.h"

/* Define variables */
#include "externdef.h"

int increment(void) { return global_variable++; }
int oddball_value(void) { return oddball_struct.a + oddball_struct.b; }

The next two files complete the source for prog8 and prog9:


#include "file2d.h"
#include <stdio.h>

int main(void)
    global_variable += 19;
    printf("Increment: %d\n", increment());
    printf("Oddball:   %d\n", oddball_value());
    return 0;


#include "file2d.h"
#include <stdio.h>

void use_them(void)
    printf("Global variable: %d\n", global_variable++);
    oddball_struct.a += global_variable;
    oddball_struct.b -= global_variable / 2;

  • prog8 uses prog8.c, file7c.c, file9c.c.

  • prog9 uses prog8.c, file8c.c, file9c.c.

However, the problems are relatively unlikely to occur in practice, especially if you take the standard advice to


Installation of SQL Server Business Intelligence Development Studio

Business Intelligence Development Studio is Microsoft Visual Studio 2008 with additional project types that are specific to SQL Server business intelligence. Business Intelligence Development Studio is the primary environment that you will use to develop business solutions that include Analysis Services, Integration Services, and Reporting Services projects. Each project type supplies templates for creating the objects required for business intelligence solutions, and provides a variety of designers, tools, and wizards to work with the objects.

If you already have Visual Studio installed, the new project types will be installed along with SQL Server.

More Information

How can I make the computer beep in C#?

In .Net 2.0, you can use Console.Beep().

// Default beep

You can also specify the frequency and length of the beep in milliseconds.

// Beep at 5000 Hz for 1 second
Console.Beep(5000, 1000);

For more information refer

How do I implement JQuery.noConflict() ?

jQuery.noConflict will reset the $ variable so it's no longer an alias of jQuery. Aside from just calling it once, there's not much else you really need to do. Though, you can create your own alias with the return value, if you'd like:

var jq = jQuery.noConflict();

And, generally, you want to do this right after including jQuery and any plugins:

<script type="text/javascript" src="/path/to/jquery.js"></script>
<script type="text/javascript" src="/path/to/jquery-plugin.js"></script>
<script type="text/javascript">
  // Code that uses other library's $ can follow here.
<script type="text/javascript" src="/path/to/prototype.js"></script>

You can also go one step further and free up jQuery with noConflict(true). Though, if you take this route, you'll definitely want an alias as neither $ nor jQuery will probably be what you want:

var jq = jQuery.noConflict(true);

I think this last option is mostly used for mixing versions of jQuery, particularly for out-dated plugins when you want to update jQuery itself:

<script type="text/javascript" src="jquery-1.4.4.js"></script>
<script type="text/javascript" src="jquery-older-plugin.js"></script>
<script type="text/javascript">
    var jq144 = jQuery.noConflict(true);
<script type="text/javascript" src="jquery-1.6.4.js"></script>
<script type="text/javascript" src="jquery-newer-plugin.js"></script>

/bin/sh: apt-get: not found

The image you're using is Alpine based, so you can't use apt-get because it's Ubuntu's package manager.

To fix this just use:

apk update and apk add

Prevent Sequelize from outputting SQL to the console on execution of query?

I am using Sequelize ORM 6.0.0 and am using "logging": false as the rest but posted my answer for latest version of the ORM.

const sequelize = new Sequelize(
            host: process.env.databaseHost,
            dialect: process.env.dialect,
            "logging": false,
            define: {
                // Table names won't be pluralized.
                freezeTableName: true,
                // All tables won't have "createdAt" and "updatedAt" Auto fields.
                timestamps: false

Note: I am storing my secretes in a configuration file .env observing the 12-factor methodology.

How to select specific form element in jQuery?

$("#name", '#form2').val("Hello World")

Using Transactions or SaveChanges(false) and AcceptAllChanges()?

Because some database can throw an exception at dbContextTransaction.Commit() so better this:

using (var context = new BloggingContext()) 
  using (var dbContextTransaction = context.Database.BeginTransaction()) 
          @"UPDATE Blogs SET Rating = 5" + 
              " WHERE Name LIKE '%Entity Framework%'" 

      var query = context.Posts.Where(p => p.Blog.Rating >= 5); 
      foreach (var post in query) 
          post.Title += "[Cool Blog]"; 



    catch (Exception) 

How to get a list of properties with a given attribute?

In addition to previous answers: it's better to use method Any() instead of check length of the collection:

propertiesWithMyAttribute = type.GetProperties()
  .Where(x => x.GetCustomAttributes(typeof(MyAttribute), true).Any());

The example at dotnetfiddle:

How can I capture the result of var_dump to a string?

From the PHP manual:

This function displays structured information about one or more expressions that includes its type and value.

So, here is the real return version of PHP's var_dump(), which actually accepts a variable-length argument list:

function var_dump_str()
    $argc = func_num_args();
    $argv = func_get_args();

    if ($argc > 0) {
        call_user_func_array('var_dump', $argv);
        $result = ob_get_contents();
        return $result;

    return '';

How to define and use function inside Jenkins Pipeline config?

First off, you shouldn't add $ when you're outside of strings ($class in your first function being an exception), so it should be:

def doCopyMibArtefactsHere(projectName) {
    step ([
        $class: 'CopyArtifact',
        projectName: projectName,
        filter: '**/**.mib',
        fingerprintArtifacts: true, 
        flatten: true

def BuildAndCopyMibsHere(projectName, params) {
    build job: project, parameters: params

Now, as for your problem; the second function takes two arguments while you're only supplying one argument at the call. Either you have to supply two arguments at the call:

node { 
    stage('Prepare Mib'){
        BuildAndCopyMibsHere('project1', null)

... or you need to add a default value to the functions' second argument:

def BuildAndCopyMibsHere(projectName, params = null) {
    build job: project, parameters: params

using CASE in the WHERE clause

FROM logs
WHERE pw='correct'
          WHEN id<800 THEN success=1
          ELSE 1=1

Failed to load resource: the server responded with a status of 404 (Not Found) css

i use firebase-database in html signup but last error i cannot understand if anybody know tell me . error is "Failed to load resource: the server responded with a status of 404 ()"

How can I check if a checkbox is checked?

Try This

<script type="text/javascript">
window.onload = function () {
    var input = document.querySelector('input[type=checkbox]');

    function check() {
        if (input.checked) {
        } else {
            alert("You didn't check it.");
    input.onchange = check;

Avoid web.config inheritance in child web application using inheritInChildApplications

If (as I understand) you're trying to completely block inheritance in the web config of your child application, I suggest you to avoid using the tag in web.config. Instead create a new apppool and edit the applicationHost.config file (located in %WINDIR%\System32\inetsrv\Config and %WINDIR%\SysWOW64\inetsrv\config). You just have to find the entry for your apppool and add the attribute enableConfigurationOverride="false" like in the following example:

<add name="MyAppPool" autoStart="true" managedRuntimeVersion="v4.0" managedPipelineMode="Integrated" enableConfigurationOverride="false">
    <processModel identityType="NetworkService" />

This will avoid configuration inheritance in the applications served by MyAppPool.


$.widget is not a function

Maybe placing the jquery.ui.widget.js as second after jquery.ui.core.js.

When is assembly faster than C?

Given the right programmer, Assembler programs can always be made faster than their C counterparts (at least marginally). It would be difficult to create a C program where you couldn't take out at least one instruction of the Assembler.

changing default x range in histogram matplotlib

the following code is for making the same y axis limit on two subplots

f ,ax = plt.subplots(1,2,figsize = (30, 13),gridspec_kw={'width_ratios': [5, 1]})
df.plot(ax = ax[0], linewidth = 2.5)
ylim = [lower_limit,upper_limit]
ax[1].hist(data,normed =1, bins = num_bin, color = 'yellow' ,alpha = 1) 

just a reminder, plt.hist(range=[low, high]) the histogram auto crops the range if the specified range is larger than the max&min of the data points. So if you want to specify the y-axis range number, i prefer to use set_ylim

C++ getters/setters coding style

Collected ideas from multiple C++ sources and put it into a nice, still quite simple example for getters/setters in C++:

class Canvas { public:
    void resize() {
        cout << "resize to " << width << " " << height << endl;

    Canvas(int w, int h) : width(*this), height(*this) {
        cout << "new canvas " << w << " " << h << endl;
        width.value = w;
        height.value = h;

    class Width { public:
        Canvas& canvas;
        int value;
        Width(Canvas& canvas): canvas(canvas) {}
        int & operator = (const int &i) {
            value = i;
            return value;
        operator int () const {
            return value;
    } width;

    class Height { public:
        Canvas& canvas;
        int value;
        Height(Canvas& canvas): canvas(canvas) {}
        int & operator = (const int &i) {
            value = i;
            return value;
        operator int () const {
            return value;
    } height;

int main() {
    Canvas canvas(256, 256);
    canvas.width = 128;
    canvas.height = 64;


new canvas 256 256
resize to 128 256
resize to 128 64

You can test it online here:

PS: FO Yvette <3

c# write text on bitmap

Bitmap bmp = new Bitmap("filename.bmp");

RectangleF rectf = new RectangleF(70, 90, 90, 50);

Graphics g = Graphics.FromImage(bmp);

g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.DrawString("yourText", new Font("Tahoma",8), Brushes.Black, rectf);



'^M' character at end of lines

The cause is the difference between how a Windows-based based OS and a Unix based OS store the end-of-line markers.

Windows based operating systems, thanks to their DOS heritage, store an end-of-line as a pair of characters - 0x0D0A (carriage return + line feed). Unix-based operating systems just use 0x0A (a line feed). The ^M you're seeing is a visual representation of 0x0D (a carriage return).

dos2unix will help with this. You probably also need to adjust the source of the scripts to be 'Unix-friendly'.

Docker error : no space left on device

Clean Docker by using the following command:

docker images --no-trunc | grep '<none>' | awk '{ print $3 }' \
| xargs docker rmi

How do I configure git to ignore some files locally?

In order to ignore untracked files especially if they are located in (a few) folders that are not tracked, a simple solution is to add a .gitignore file to every untracked folder and enter in a single line containing * followed by a new line. It's a really simple and straightforward solution if the untracked files are in a few folders. For me, all files were coming from a single untracked folder vendor and the above just worked.

OpenCV resize fails on large image with "error: (-215) ssize.area() > 0 in function cv::resize"

For me the following work-around worked:

  • split the array up into smaller sub arrays
  • resize the sub arrays
  • merge the sub arrays again

Here the code:

def split_up_resize(arr, res):
    function which resizes large array (direct resize yields error (addedtypo))

    # compute destination resolution for subarrays
    res_1 = (res[0], res[1]/2)
    res_2 = (res[0], res[1] - res[1]/2)

    # get sub-arrays
    arr_1 = arr[0 : len(arr)/2]
    arr_2 = arr[len(arr)/2 :]

    # resize sub arrays
    arr_1 = cv2.resize(arr_1, res_1, interpolation = cv2.INTER_LINEAR)
    arr_2 = cv2.resize(arr_2, res_2, interpolation = cv2.INTER_LINEAR)

    # init resized array
    arr = np.zeros((res[1], res[0]))

    # merge resized sub arrays
    arr[0 : len(arr)/2] = arr_1
    arr[len(arr)/2 :] = arr_2

    return arr

Applying styles to tables with Twitter Bootstrap

you can Add contextual classes to every single row as follows:

<tr class="table-success"></tr>
<tr class="table-error"></tr>
<tr class="table-warning"></tr>
<tr class="table-info"></tr>
<tr class="table-danger"></tr>

You can also add them to table data same as above

You can set your table size by setting classes as table-sm and so on.

You can add custom classes and add your own styling:

<table class="table">
  <thead style = "color:red;background-color:blue">
      <th>First Name</th>
      <th>Last Name</th>

This way you can add custom styling. I have showed inline styling just for example how it works, you can add classes and call them in your css as well.

file_get_contents behind a proxy?

Depending on how the proxy login works stream_context_set_default might help you.

$context  = stream_context_set_default(
      'header'=>'Authorization: Basic ' . base64_encode('username'.':'.'userpass')
$result = file_get_contents('http://..../...');

Sort Dictionary by keys

let dictionary = [
    "A" : [1, 2],
    "Z" : [3, 4],
    "D" : [5, 6]

let sortedKeys = Array(dictionary.keys).sorted(<) // ["A", "D", "Z"]


The sorted array from the above code contains keys only, while values have to be retrieved from the original dictionary. However, 'Dictionary' is also a 'CollectionType' of (key, value) pairs and we can use the global 'sorted' function to get a sorted array containg both keys and values, like this:

let sortedKeysAndValues = sorted(dictionary) { $0.0 < $1.0 }
println(sortedKeysAndValues) // [(A, [1, 2]), (D, [5, 6]), (Z, [3, 4])]

EDIT2: The monthly changing Swift syntax currently prefers

let sortedKeys = Array(dictionary.keys).sort(<) // ["A", "D", "Z"]

The global sorted is deprecated.

Custom Date Format for Bootstrap-DatePicker

I solve it editing the file bootstrap-datapicker.js.

Look for the text bellow in the file and edit the variable "Format:"

var defaults = $.fn.datepicker.defaults = {
    assumeNearbyYear: false,
    autoclose: false,
    beforeShowDay: $.noop,
    beforeShowMonth: $.noop,
    beforeShowYear: $.noop,
    beforeShowDecade: $.noop,
    beforeShowCentury: $.noop,
    calendarWeeks: false,
    clearBtn: false,
    toggleActive: false,
    daysOfWeekDisabled: [],
    daysOfWeekHighlighted: [],
    datesDisabled: [],
    endDate: Infinity,
    forceParse: true,
    format: 'dd/mm/yyyy',
    keyboardNavigation: true,
    language: 'en',
    minViewMode: 0,
    maxViewMode: 4,
    multidate: false,
    multidateSeparator: ',',
    orientation: "auto",
    rtl: false,
    startDate: -Infinity,
    startView: 0,
    todayBtn: false,
    todayHighlight: false,
    weekStart: 0,
    disableTouchKeyboard: false,
    enableOnReadonly: true,
    showOnFocus: true,
    zIndexOffset: 10,
    container: 'body',
    immediateUpdates: false,
    title: '',
    templates: {
        leftArrow: '&laquo;',
        rightArrow: '&raquo;'

Tracing XML request/responses with JAX-WS

One way to do is not using your code but use network packet sniffers like Etheral or WireShark which can capture the HTTP packet with the XML message as payload to it and you can keep logging them to a file or so.

But more sophisticated approach is to write your own message handlers. You can have a look at it here.

Jquery Ajax, return success/error from controller

Use Json class instead of Content as shown following:

    //  When I want to return an error:
    if (!isFileSupported)
        Response.StatusCode = (int) HttpStatusCode.BadRequest;
        return Json("The attached file is not supported", MediaTypeNames.Text.Plain);
        //  When I want to return sucess:
        Response.StatusCode = (int)HttpStatusCode.OK; 
        return Json("Message sent!", MediaTypeNames.Text.Plain);

Also set contentType:

contentType: 'application/json; charset=utf-8',

Automatically create requirements.txt

I blindly followed the accepted answer of using pip3 freeze > requirements.txt

It generated a huge file that listed all the dependencies of the entire solution, which is not what I wanted.

So you need to figure out what sort of requirements.txt you are trying to generate.

If you need a requirements.txt file that has ALL the dependencies, then use the pip3

pip3 freeze > requirements.txt

However, if you want to generate a minimal requirements.txt that only lists the dependencies you need, then use the pipreqs package. Especially helpful if you have numerous requirements.txt files in per component level in the project and not a single file on the solution wide level.

pip install pipreqs
pipreqs [path to folder]
e.g. pipreqs .

Add text to textarea - Jquery

That should work. Better if you pass a function to val:

$('#replyBox').val(function(i, text) {
    return text + quote;

This way you avoid searching the element and calling val twice.

Best way to find the months between two dates

Define a "month" as 1/12 year, then do this:

def month_diff(d1, d2): 
    """Return the number of months between d1 and d2, 
    such that d2 + month_diff(d1, d2) == d1
    diff = (12 * d1.year + d1.month) - (12 * d2.year + d2.month)
    return diff

You might try to define a month as "a period of either 29, 28, 30 or 31 days (depending on the year)". But you you do that, you have an additional problem to solve.

While it's usually clear that June 15th + 1 month should be July 15th, it's not usually not clear if January 30th + 1 month is in February or March. In the latter case, you may be compelled to compute the date as February 30th, then "correct" it to March 2nd. But when you do that, you'll find that March 2nd - 1 month is clearly February 2nd. Ergo, reductio ad absurdum (this operation is not well defined).

Resizing an Image without losing any quality

See if you like the image resizing quality of this open source ASP.NET module. There's a live demo, so you can mess around with it yourself. It yields results that are (to me) impossible to distinguish from Photoshop output. It also has similar file sizes - MS did a good job on their JPEG encoder.

No visible cause for "Unexpected token ILLEGAL"

I had the same problem on my mac and found it was because the Mac was replacing the standard quotes with curly quotes which are illegal javascript characters.

To fix this I had to change the settings on my mac System Preferences=>Keyboard=>Text(tab) uncheck use smart quotes and dashes (default was checked).

how to fix the issue "Command /bin/sh failed with exit code 1" in iphone

just put your script in a file and run that file with 2>/dev/null at the end of command line!

This way, if there is a problem with the command whatsoever, it will not halt your xcode build

in my case I was running just a command to uninstall my previous copy of the app from a connected iphone, so it could give an error if the iphone is not there. To solve it:

$mobiledevice uninstall_app 2>/dev/null

'' is not recognized as an internal or external command, operable program or batch file

When you want to run an executable file from the Command prompt, (cmd.exe), or a batch file, it will:

  • Search the current working directory for the executable file.
  • Search all locations specified in the %PATH% environment variable for the executable file.

If the file isn't found in either of those options you will need to either:

  1. Specify the location of your executable.
  2. Change the working directory to that which holds the executable.
  3. Add the location to %PATH% by apending it, (recommended only with extreme caution).

You can see which locations are specified in %PATH% from the Command prompt, Echo %Path%.

Because of your reported error we can assume that Mobile.exe is not in the current directory or in a location specified within the %Path% variable, so you need to use 1., 2. or 3..

Examples for 1.



"C:\directory path with spaces\My-App\Mobile.exe"

Alternatively you may try:

Start C:\directory_path_without_spaces\My-App\Mobile.exe


Start "" "C:\directory path with spaces\My-App\Mobile.exe"

Where "" is an empty title, (you can optionally add a string between those doublequotes).

Examples for 2.

CD /D C:\directory_path_without_spaces\My-App


CD /D "C:\directory path with spaces\My-App"

You could also use the /D option with Start to change the working directory for the executable to be run by the start command

Start /D C:\directory_path_without_spaces\My-App Mobile.exe


Start "" /D "C:\directory path with spaces\My-App" Mobile.exe

Angular 2 Routing run in new tab

This seems a little confused.

Opening your application in another window or tab will require your entire application to be re-bootstrapped, and then for your router to... pick up that url, convert it into a route, and load the appropriate component.

This is exactly what will happen if you just use a link instead. In fact, that's all that's happening.

The point of the router is to swap components in and out of your router-outlet, which is something that's been bootstrapped and exists within the confines of your running application and isn't shared across multiple windows.

How to develop or migrate apps for iPhone 5 screen resolution?

This is a real universal code, you can create 3 different story board:

Set your project Universal mode, and set your main story iPhone with the iPhone5 storyboard and the ipad main with iPad target storyboard, now add new storyboard target for iphone and modify the resolution for iphone 4s or less now implement your AppDelegate.m

iPhone4/4s (is the same for 3/3Gs) one for iPhone5 and make the project universal, with a new Storyboard target for iPad, now in to AppDelegate.m under the didFinishLaunching add this code:

    if(UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone){
        UIStoryboard *storyBoard;

        CGSize result = [[UIScreen mainScreen] bounds].size;
        CGFloat scale = [UIScreen mainScreen].scale;
        result = CGSizeMake(result.width *scale, result.height *scale);

//----------------HERE WE SETUP FOR IPHONE4/4s/iPod----------------------

        if(result.height == 960){
            storyBoard = [UIStoryboard storyboardWithName:@"iPhone4_Storyboard" bundle:nil];
            UIViewController *initViewController = [storyBoard instantiateInitialViewController];
            [self.window setRootViewController:initViewController];

//----------------HERE WE SETUP FOR IPHONE3/3s/iPod----------------------

        if(result.height == 480){
            storyBoard = [UIStoryboard storyboardWithName:@"iPhone4_Storyboard" bundle:nil];
            UIViewController *initViewController = [storyBoard instantiateInitialViewController];
            [self.window setRootViewController:initViewController];

        return YES;

So you have created a Universal app for iPhone 3/3Gs/4/4s/5 All gen of iPod, and All type of iPad

Remember to integrate all IMG with myImage.png and [email protected]

How do you declare string constants in C?

The main disadvantage of the #define method is that the string is duplicated each time it is used, so you can end up with lots of copies of it in the executable, making it bigger.

jquery to loop through table rows and cells, where checkob is checked, concatenate


I've updated your demo:

Also, I've changed two ^= to *=. See

And note the :checked selector. See

function createcodes() {

    //run through each row
    $('.authors-list tr').each(function (i, row) {

        // reference all the stuff you need first
        var $row = $(row),
            $family = $row.find('input[name*="family"]'),
            $grade = $row.find('input[name*="grade"]'),
            $checkedBoxes = $row.find('input:checked');

        $checkedBoxes.each(function (i, checkbox) {
            // assuming you layout the elements this way, 
            // we'll take advantage of .next()
            var $checkbox = $(checkbox),
                $line = $,
                $size = $;

                $family.val() + ' ' + $size.val() + ', ' + $grade.val()



How to print a int64_t type in C

The C99 way is

#include <inttypes.h>
int64_t my_int = 999999999999999999;
printf("%" PRId64 "\n", my_int);

Or you could cast!

printf("%ld", (long)my_int);
printf("%lld", (long long)my_int); /* C89 didn't define `long long` */
printf("%f", (double)my_int);

If you're stuck with a C89 implementation (notably Visual Studio) you can perhaps use an open source <inttypes.h> (and <stdint.h>):

Setting environment variables for accessing in PHP when using Apache

If your server is Ubuntu and Apache version is 2.4

Server version: Apache/2.4.29 (Ubuntu)

Then you export variables in "/etc/apache2/envvars" location.

Just like this below line, you need to add an extra line in "/etc/apache2/envvars" export GOROOT=/usr/local/go

Necessary to add link tag for favicon.ico?

To choose a different location or file type (e.g. PNG or SVG) for the favicon:
One reason can be that you want to have the icon in a specific location, perhaps in the images folder or something alike. For example:

<link rel="icon" href="_/img/favicon.png">

This diferent location may even be a CDN, just like SO seems to do with <link rel="shortcut icon" href="">.

To learn more about using other file types like PNG check out this question.

For cache busting purposes:
Add a query string to the path for cache-busting purposes:

<link rel="icon" href="/favicon.ico?v=1.1"> 

Favicons are very heavily cached and this a great way to ensure a refresh.

Footnote about default location:
As far as the first bit of the question: all modern browsers would detect a favicon at the default location, so that's not a reason to use a link for it.

Footnote about rel="icon":
As indicated by @Semanino's answer, using rel="shortcut icon" is an old technique which was required by older versions of Internet Explorer, but in most cases can be replaced by the more correct rel="icon" instruction. The article @Semanino based this on properly links to the appropriate spec which shows a rel value of shortcut isn't a valid option.

go to link on button click - jquery

$('.button1').click(function() {
   window.location = "" +;

First of all using window.location is better as according to specification document.location value was read-only and might cause you headaches in older/different browsers. Check notes @MDC DOM document.location page

And for the second - using attr jQuery method to get id is a bad practice - you should use direct native DOM accessor as the value assigned to this is normal DOM element.

'nuget' is not recognized but other nuget commands working

  • Right-click on your project in solution explorer.
  • Select Manage NuGet Packages for Solution.
  • Search NuGet.CommandLine by Microsoft and Install it. Search Nuget.CommandLine
  • On complete installation, you will find a folder named packages in your project. Go to solution explorer and look for it. packages
  • Inside packages look for a folder named NuGet.CommandLine.3.5.0, here 3.5.0 is just version name your folder name will change accordingly. nuGet COmmand Line
  • Inside NuGet.CommandLine.3.5.0 look for a folder named tools. tools
  • Inside tools you will get your nuget.exe nuget.exe

Parsing HTML using Python

Compared to the other parser libraries lxml is extremely fast:

And with cssselect it’s quite easy to use for scraping HTML pages too:

from lxml.html import parse
doc = parse('').getroot()
for div in doc.cssselect('a'):
    print '%s: %s' % (div.text_content(), div.get('href'))

lxml.html Documentation

How to check if an element does NOT have a specific class?

Select element (or group of elements) having class "abc", not having class "xyz":


When selecting regular CSS you can use .abc:not(.xyz).

How to check if user input is not an int value

Try this one:

    for (;;) {
        if (!sc.hasNextInt()) {
            System.out.println(" enter only integers!: ");
  ; // discard
        choose = sc.nextInt();
        if (choose >= 0) {
            System.out.print("no problem with input");

        } else {
            System.out.print("invalid inputs");


Difference between Hive internal tables and external tables?

To answer you Question :

For External Tables, Hive stores the data in the LOCATION specified during creation of the table(generally not in warehouse directory). If the external table is dropped, then the table metadata is deleted but not the data.

For Internal tables, Hive stores data into its warehouse directory. If the table is dropped then both the table metadata and the data will be deleted.

For your reference,

Difference between Internal & External tables :

For External Tables -

  • External table stores files on the HDFS server but tables are not linked to the source file completely.

  • If you delete an external table the file still remains on the HDFS server.

    As an example if you create an external table called “table_test” in HIVE using HIVE-QL and link the table to file “file”, then deleting “table_test” from HIVE will not delete “file” from HDFS.

  • External table files are accessible to anyone who has access to HDFS file structure and therefore security needs to be managed at the HDFS file/folder level.

  • Meta data is maintained on master node, and deleting an external table from HIVE only deletes the metadata not the data/file.

For Internal Tables-

  • Stored in a directory based on settings in hive.metastore.warehouse.dir, by default internal tables are stored in the following directory “/user/hive/warehouse” you can change it by updating the location in the config file .
  • Deleting the table deletes the metadata and data from master-node and HDFS respectively.
  • Internal table file security is controlled solely via HIVE. Security needs to be managed within HIVE, probably at the schema level (depends on organization).

Hive may have internal or external tables, this is a choice that affects how data is loaded, controlled, and managed.

Use EXTERNAL tables when:

  • The data is also used outside of Hive. For example, the data files are read and processed by an existing program that doesn’t lock the files.
  • Data needs to remain in the underlying location even after a DROP TABLE. This can apply if you are pointing multiple schema (tables or views) at a single data set or if you are iterating through various possible schema.
  • Hive should not own data and control settings, directories, etc., you may have another program or process that will do those things.
  • You are not creating table based on existing table (AS SELECT).

Use INTERNAL tables when:

  • The data is temporary.
  • You want Hive to completely manage the life-cycle of the table and data.

Source :

HDInsight: Hive Internal and External Tables Intro

Internal & external tables in Hadoop- HIVE

Can we use join for two different database tables?

SQL Server allows you to join tables from different databases as long as those databases are on the same server. The join syntax is the same; the only difference is that you must fully specify table names.

Let's suppose you have two databases on the same server - Db1 and Db2. Db1 has a table called Clients with a column ClientId and Db2 has a table called Messages with a column ClientId (let's leave asside why those tables are in different databases).

Now, to perform a join on the above-mentioned tables you will be using this query:

select *
from Db1.dbo.Clients c
join Db2.dbo.Messages m on c.ClientId = m.ClientId

Authentication failed because remote party has closed the transport stream

Adding the below code helped me overcome the issue.

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls11;

How to redirect DNS to different ports

Since I had troubles understanding this post here is a simple explanation for people like me. It is useful if:

  • You DO NOT need Load Balacing.
  • You DO NOT want to use nginx to do port forwarding.
  • You DO want to do PORT FORWARDING according to specific subdomains using SRV record.

Then here is what you need to do:

SRV records:

_minecraft._tcp.1.12          IN SRV    1 100 25567 1.12.<>.
_minecraft._tcp.1.13          IN SRV    1 100 25566 1.13.<>.

(I did not need a srv record for 1.14 since my 1.14 minecraft server was already on the 25565 port which is the default port of minecraft.)

And the A records:

1.12                          IN A      <your server IP>
1.13                          IN A      <your server IP>
1.14                          IN A      <your server IP>

Best way to implement keyboard shortcuts in a Windows Forms application?

Hans's answer could be made a little easier for someone new to this, so here is my version.

You do not need to fool with KeyPreview, leave it set to false. To use the code below, just paste it below your form1_load and run with F5 to see it work:

protected override void OnKeyPress(KeyPressEventArgs ex)
    string xo = ex.KeyChar.ToString();

    if (xo == "q") //You pressed "q" key on the keyboard
        Form2 f2 = new Form2();

Creating the checkbox dynamically using JavaScript?

   /* worked for me  */
     <div id="divid"> </div>
     <script type="text/javascript">
         var hold = document.getElementById("divid");
         var checkbox = document.createElement('input');
         checkbox.type = "checkbox"; = "chkbox1"; = "cbid";
         var label = document.createElement('label');
         var tn = document.createTextNode("Not A RoBot");

How do I force my .NET application to run as administrator?

Right click your executable, go to Properties > Compatibility and check the 'Run this program as admin' box.

If you want to run it as admin for all users, do the same thing in 'change setting for all users'.

Convert time in HH:MM:SS format to seconds only?

    $time = 00:06:00;
    $timeInSeconds = strtotime($time) - strtotime('TODAY');

BigDecimal to string

By using below method you can convert java.math.BigDecimal to String.

   BigDecimal bigDecimal = new BigDecimal("10.0001");
   String bigDecimalString = String.valueOf(bigDecimal.doubleValue());
   System.out.println("bigDecimal value in String: "+bigDecimalString);

bigDecimal value in String: 10.0001

What are the best practices for SQLite on Android?

Having had some issues, I think I have understood why I have been going wrong.

I had written a database wrapper class which included a close() which called the helper close as a mirror of open() which called getWriteableDatabase and then have migrated to a ContentProvider. The model for ContentProvider does not use SQLiteDatabase.close() which I think is a big clue as the code does use getWriteableDatabase In some instances I was still doing direct access (screen validation queries in the main so I migrated to a getWriteableDatabase/rawQuery model.

I use a singleton and there is the slightly ominous comment in the close documentation

Close any open database object

(my bolding).

So I have had intermittent crashes where I use background threads to access the database and they run at the same time as foreground.

So I think close() forces the database to close regardless of any other threads holding references - so close() itself is not simply undoing the matching getWriteableDatabase but force closing any open requests. Most of the time this is not a problem as the code is single threading, but in multi-threaded cases there is always the chance of opening and closing out of sync.

Having read comments elsewhere that explains that the SqLiteDatabaseHelper code instance counts, then the only time you want a close is where you want the situation where you want to do a backup copy, and you want to force all connections to be closed and force SqLite to write away any cached stuff that might be loitering about - in other words stop all application database activity, close just in case the Helper has lost track, do any file level activity (backup/restore) then start all over again.

Although it sounds like a good idea to try and close in a controlled fashion, the reality is that Android reserves the right to trash your VM so any closing is reducing the risk of cached updates not being written, but it cannot be guaranteed if the device is stressed, and if you have correctly freed your cursors and references to databases (which should not be static members) then the helper will have closed the database anyway.

So my take is that the approach is:

Use getWriteableDatabase to open from a singleton wrapper. (I used a derived application class to provide the application context from a static to resolve the need for a context).

Never directly call close.

Never store the resultant database in any object that does not have an obvious scope and rely on reference counting to trigger an implicit close().

If doing file level handling, bring all database activity to a halt and then call close just in case there is a runaway thread on the assumption that you write proper transactions so the runaway thread will fail and the closed database will at least have proper transactions rather than potentially a file level copy of a partial transaction.

How can I edit a .jar file?

Here's what I did:

  • Extracted the files using WinRAR
  • Made my changes to the extracted files
  • Opened the original JAR file with WinRAR
  • Used the ADD button to replace the files that I modified

That's it. I have tested it with my Nokia and it's working for me.

Is it possible to use pip to install a package from a private GitHub repository?

If you need to do this in, say, a command line one-liner, it's also possible. I was able to do this for deployment on Google Colab:

  1. Create a Personal Access Token:
  2. Run: pip install git+https://<PERSONAL ACCESS TOKEN><USERNAME>/<REPOSITORY>.git

Templated check for the existence of a class member function?

There are a lot of answers here, but I failed, to find a version, that performs real method resolution ordering, while not using any of the newer c++ features (only using c++98 features).
Note: This version is tested and working with vc++2013, g++ 5.2.0 and the onlline compiler.

So I came up with a version, that only uses sizeof():

template<typename T> T declval(void);

struct fake_void { };
template<typename T> T &operator,(T &,fake_void);
template<typename T> T const &operator,(T const &,fake_void);
template<typename T> T volatile &operator,(T volatile &,fake_void);
template<typename T> T const volatile &operator,(T const volatile &,fake_void);

struct yes { char v[1]; };
struct no  { char v[2]; };
template<bool> struct yes_no:yes{};
template<> struct yes_no<false>:no{};

template<typename T>
struct has_awesome_member {
 template<typename U> static yes_no<(sizeof((
  ))!=0)> check(int);
 template<typename> static no check(...);
 enum{value=sizeof(check<T>(0)) == sizeof(yes)};

struct foo { int awesome_member(void); };
struct bar { };
struct foo_void { void awesome_member(void); };
struct wrong_params { void awesome_member(int); };


Live demo (with extended return type checking and vc++2010 workaround):

No source, as I came up with it myself.

When running the Live demo on the g++ compiler, please note that array sizes of 0 are allowed, meaning that the static_assert used will not trigger a compiler error, even when it fails.
A commonly used work-around is to replace the 'typedef' in the macro with 'extern'.

What is ROWS UNBOUNDED PRECEDING used for in Teradata?

It's the "frame" or "range" clause of window functions, which are part of the SQL standard and implemented in many databases, including Teradata.

A simple example would be to calculate the average amount in a frame of three days. I'm using PostgreSQL syntax for the example, but it will be the same for Teradata:

WITH data (t, a) AS (
  VALUES(1, 1),
        (2, 5),
        (3, 3),
        (4, 5),
        (5, 4),
        (6, 11)
FROM data

... which yields:

t  a  avg
1  1  3.00
2  5  3.00
3  3  4.33
4  5  4.00
5  4  6.67
6 11  7.50

As you can see, each average is calculated "over" an ordered frame consisting of the range between the previous row (1 preceding) and the subsequent row (1 following).

When you write ROWS UNBOUNDED PRECEDING, then the frame's lower bound is simply infinite. This is useful when calculating sums (i.e. "running totals"), for instance:

WITH data (t, a) AS (
  VALUES(1, 1),
        (2, 5),
        (3, 3),
        (4, 5),
        (5, 4),
        (6, 11)
FROM data


t  a  sum
1  1    1
2  5    6
3  3    9
4  5   14
5  4   18
6 11   29

Here's another very good explanations of SQL window functions.

Googlemaps API Key for Localhost

Where it says "Accept requests from these HTTP referrers (websites) (Optional)" you don't need to have any referrer listed. So click the X beside localhost on this page but continue to use your key.

It should then work after a few minutes.

Changes made can sometimes take a few minutes to take effect so wait a few minutes before testing again.

Force encode from US-ASCII to UTF-8 (iconv)

Here's a script that will find all files matching a pattern you pass it, and then converting them from their current file encoding to UTF-8. If the encoding is US ASCII, then it will still show as US ASCII, since that is a subset of UTF-8.

#!/usr/bin/env bash
find . -name "${1}" |
    while read line;
        echo "***************************"
        echo "Converting ${line}"

        encoding=$(file -b --mime-encoding ${line})
        echo "Found Encoding: ${encoding}"

        iconv -f "${encoding}" -t "utf-8" ${line} -o ${line}.tmp
        mv ${line}.tmp ${line}

How to mention C:\Program Files in batchfile

use this as somethink

"C:/Program Files (x86)/Nox/bin/nox_adb" install -r app.apk


"path_to_executable" commands_argument

Accessing a value in a tuple that is in a list

a = [(0,2), (4,3), (9,9), (10,-1)]
print(list(map(lambda item: item[1], a)))

ModelState.IsValid == false, why?

As has just happened to me - this can also happen when you add a required property to your model without updating your form. In this case the ValidationSummary will not list the error message.

Add JVM options in Tomcat

After checking (for windows use the .bat versions of everything mentioned below)

#   Do not set the variables in this script. Instead put them into a script
# in CATALINA_BASE/bin to keep your customizations separate.

Also this

#   CATALINA_OPTS   (Optional) Java runtime options used when the "start",
#                   "run" or "debug" command is executed.
#                   Include here and not in JAVA_OPTS all options, that should
#                   only be used by Tomcat itself, not by the stop process,
#                   the version command etc.
#                   Examples are heap size, GC logging, JMX ports etc

So create a under CATALINA_BASE/bin (same dir where the resides). Edit the file and set the arguments to CATALINA_OPTS

For e.g. the file would look like this if you wanted to change the heap size


Or in your case since you're using windows setenv.bat would be

set CATALINA_OPTS=-agentpath:C:\calltracer\jvmti\calltracer5.dll=traceFile-C:\calltracer\call.trace,filterFile-C:\calltracer\filters.txt,outputType-xml,usage-uncontrolled -Djava.library.path=C:\calltracer\jvmti -Dcalltracerlib=calltracer5

To clear the added options later just delete setenv.bat/sh

How to prevent form from submitting multiple times from client side?

This works very fine for me. It submit the farm and make button disable and after 2 sec active the button.

<button id="submit" type="submit" onclick="submitLimit()">Yes</button>

function submitLimit() {
var btn = document.getElementById('submit')
setTimeout(function() {
    btn.setAttribute('disabled', 'disabled');
}, 1);

setTimeout(function() {
}, 2000);}

In ECMA6 Syntex

function submitLimit() {
submitBtn = document.getElementById('submit');

setTimeout(() => { submitBtn.setAttribute('disabled', 'disabled') }, 1);

setTimeout(() => { submitBtn.removeAttribute('disabled') }, 4000);}

How to get current PHP page name

In your case you can use __FILE__ variable !
It should help.
It is one of predefined.
Read more about predefined constants in PHP

Use of Greater Than Symbol in XML

CDATA is a better general solution.

jQuery/JavaScript: accessing contents of an iframe

You need to attach an event to an iframe's onload handler, and execute the js in there, so that you make sure the iframe has finished loading before accessing it.

$().ready(function () {
    $("#iframeID").ready(function () { //The function below executes once the iframe has finished loading
        $('some selector', frames['nameOfMyIframe'].document).doStuff();

The above will solve the 'not-yet-loaded' problem, but as regards the permissions, if you are loading a page in the iframe that is from a different domain, you won't be able to access it due to security restrictions.

The requested resource does not support HTTP method 'GET'

Resolved this issue by using http(s) when accessing the endpoint. The route I was accessing was not available over http. So I would say verify the protocols for which the route is available.

C++ templates that accept only certain types

There is no keyword for such type checks, but you can put some code in that will at least fail in an orderly fashion:

(1) If you want a function template to only accept parameters of a certain base class X, assign it to a X reference in your function. (2) If you want to accept functions but not primitives or vice versa, or you want to filter classes in other ways, call a (empty) template helper function within your function that's only defined for the classes you want to accept.

You can use (1) and (2) also in member functions of a class to force these type checks on the entire class.

You can probably put it into some smart Macro to ease your pain. :)

How to detect Esc Key Press in React and how to handle it

You'll want to listen for escape's keyCode (27) from the React SyntheticKeyBoardEvent onKeyDown:

const EscapeListen = React.createClass({
  handleKeyDown: function(e) {
    if (e.keyCode === 27) {
      console.log('You pressed the escape key!')

  render: function() {
    return (
      <input type='text'
             onKeyDown={this.handleKeyDown} />

Brad Colthurst's CodePen posted in the question's comments is helpful for finding key codes for other keys.

Allow multi-line in EditText view in Android?

I learned this from, though I don't like the website myself. If you want multiline BUT want to retain the enter button as a post button, set the listview's "horizontally scrolling" to false.


If it doesn't work in xml, doing it programmatically weirdly works.


How to evaluate http response codes from bash/shell script?

i didn't like the answers here that mix the data with the status. found this: you add the -f flag to get curl to fail and pick up the error status code from the standard status var: $?

i don't know if it's perfect for every scenario here, but it seems to fit my needs and i think it's much easier to work with

Table 'performance_schema.session_variables' doesn't exist

If, while using the mysql_upgrade -u root -p --force command You get this error:

Could not create the upgrade info file '/var/lib/mysql/mysql_upgrade_info' in the MySQL Servers datadir, errno: 13

just add the sudo before the command. That worked for me, and I solved my problem. So, it's: sudo mysql_upgrade -u root -p --force :)

How to trim a string in SQL Server before 2017?

Extended version of "REPLACE":

REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(RTRIM(LTRIM(REPLACE("Put in your Field name", ' ',' '))),'''',''), CHAR(9), ''), CHAR(10), ''), CHAR(13), ''), CHAR(160), '') [CorrValue]



  FROM TableName

Oracle & DB2

     , LISTAGG(FieldB, ',') WITHIN GROUP (ORDER BY FieldB) AS FieldBs
  FROM TableName


     , STRING_AGG(FieldB, ',' ORDER BY FieldB) AS FieldBs
  FROM TableName

SQL Server

SQL Server ≥ 2017 & Azure SQL

     , STRING_AGG(FieldB, ',') WITHIN GROUP (ORDER BY FieldB) AS FieldBs
  FROM TableName

SQL Server ≤ 2016 (CTE included to encourage the DRY principle)

  WITH CTE_TableName AS (
       SELECT FieldA, FieldB
         FROM TableName)
SELECT t0.FieldA
     , STUFF((
       SELECT ',' + t1.FieldB
         FROM CTE_TableName t1
        WHERE t1.FieldA = t0.FieldA
        ORDER BY t1.FieldB
          FOR XML PATH('')), 1, LEN(','), '') AS FieldBs
  FROM CTE_TableName t0
 GROUP BY t0.FieldA


Ordering requires a CTE or subquery

  WITH CTE_TableName AS (
       SELECT FieldA, FieldB
         FROM TableName
        ORDER BY FieldA, FieldB)
     , GROUP_CONCAT(FieldB, ',') AS FieldBs
  FROM CTE_TableName

Without ordering

     , GROUP_CONCAT(FieldB, ',') AS FieldBs
  FROM TableName

Video auto play is not working in Safari and Chrome desktop browser

I had a case where it had something to do with the order of the different filetypes. Try to change it and see if that helps.

Selenium: WebDriverException:Chrome failed to start: crashed as google-chrome is no longer running so ChromeDriver is assuming that Chrome has crashed

A simple solution that no one else has said but worked for me was not running without sudo or not as root.

What is &amp used for

if you're doing a string of characters. make:

let linkGoogle = ''; 
let origin = '&origin=' + locations[0][1] + ',' + locations[0][2];

aNav.href = linkGoogle + origin;

Safe width in pixels for printing web pages?

A printer doesn't understand pixels, it understand dots (pt in CSS). The best solution is to write an extra CSS for printing, with all of its measures in dots.

Then, in your HTML code, in head section, put:

<link href="style.css" rel="stylesheet" type="text/css" media="screen">
<link href="style_print.css" rel="stylesheet" type="text/css" media="print">

Plotting with ggplot2: "Error: Discrete value supplied to continuous scale" on categorical y-axis

if x is numeric, then add scale_x_continuous(); if x is character/factor, then add scale_x_discrete(). This might solve your problem.

Send message to specific client with and node.js

In 1.0 you should use:


How can I check if a MySQL table exists with PHP?

125 microsecond table exists check

.000125 sec. (125µs)

mysql_unbuffered_query("SET profiling = 1");  // for profiling only

@mysql_unbuffered_query("SELECT 1 FROM `table` LIMIT 1 ");
if (mysql_errno() == 1146){


elseif(mysql_errno() > 0){

  echo mysql_error();    


$results = mysql_query("SHOW PROFILE");  // for profiling only

Execution time, measured using mysql profiling, when a table exists, or not, is about .000125 sec. (125µs)

The LIMIT 1 is important for speed. This minimizes the Sorting Result and Sending Data query State times. And table size is not a factor.

I always use an unbuffered query when no results are required.


--------------------  -------
starting              0.000025  
checking permissions  0.000006  
Opening tables        0.000065  
query end             0.000005  
closing tables        0.000003  
freeing items         0.000013  
logging slow query    0.000003  
cleaning up           0.000003  
TOTAL                 0.000123  <<<<<<<<<<<< 123 microseconds


--------------------  -------
starting              0.000024
checking permissions  0.000005
Opening tables        0.000013
System lock           0.000007
init                  0.000006
optimizing            0.000003
statistics            0.000009
preparing             0.000008
executing             0.000003
Sending data          0.000019
end                   0.000004
query end             0.000004
closing tables        0.000006
freeing items         0.00001
logging slow query    0.000003
cleaning up           0.000003
TOTAL                 0.000127 <<<<<<<<<<<< 127 microseconds

How to check if a process is in hang state (Linux)

What do you mean by ‘hang state’? Typically, a process that is unresponsive and using 100% of a CPU is stuck in an endless loop. But there's no way to determine whether that has happened or whether the process might not eventually reach a loop exit state and carry on.

Desktop hang detectors just work by sending a message to the application's event loop and seeing if there's any response. If there's not for a certain amount of time they decide the app has ‘hung’... but it's entirely possible it was just doing something complicated and will come back to life in a moment once it's done. Anyhow, that's not something you can use for any arbitrary process.

how to avoid a new line with p tag?

I came across this for css

span, p{overflow:hidden; white-space: nowrap;}

via similar stackoverflow question

MySQL load NULL values from CSV data

Preprocess your input CSV to replace blank entries with \N.

Attempt at a regex: s/,,/,\n,/g and s/,$/,\N/g

Good luck.

Comparing the contents of two files in Sublime Text

The Diff Option only appears if the files are in a folder that is part of a Project.

Than you can actually compare files natively right in Sublime Text.

Navigate to the folder containing them through Open Folder... or in a project Select the two files (ie, by holding Ctrl on Windows or ? on macOS) you want to compare in the sidebar Right click and select the Diff files... option.

How to make image hover in css?

Exact solution to your problem

You can change the image on hover by using content:url("YOUR-IMAGE-PATH");

For image hover use below line in your css:


and to change the image on hover using the below config inside img:hover:


Google Android USB Driver and ADB

instead of modifying adb_usb.ini file I made changes on the file android_winusb.inf under directory android-sdk\extras\google\usb_driver\ alone and it worked for the tablet MID Q88 but i copied both sections [Google.NTamd64] and [Google.NTx86]

;Google MID Q88
%SingleAdbInterface%        = USB_INSTALL, USB\VID_18D1&PID_0003&MI_01
%CompositeAdbInterface%     = USB_INSTALL, USB\VID_18D1&PID_0003&REV_0230&MI_01

What is difference between Errors and Exceptions?

Error and Exception both extend Throwable, but mostly Error is thrown by JVM in a scenario which is fatal and there is no way for the application program to recover from that error. For instance OutOfMemoryError.

Though even application can raise an Error but its just not a good a practice, instead applications should use checked exceptions for recoverable conditions and runtime exceptions for programming errors.

Making a flex item float right

You can't use float inside flex container and the reason is that float property does not apply to flex-level boxes as you can see here Fiddle.

So if you want to position child element to right of parent element you can use margin-left: auto but now child element will also push other div to the right as you can see here Fiddle.

What you can do now is change order of elements and set order: 2 on child element so it doesn't affect second div

.parent {_x000D_
  display: flex;_x000D_
.child {_x000D_
  margin-left: auto;_x000D_
  order: 2;_x000D_
<div class="parent">_x000D_
  <div class="child">Ignore parent?</div>_x000D_
  <div>another child</div>_x000D_

How to fill DataTable with SQL Table

You need to modify the method GetData() and add your "experimental" code there, and return t1.

Why do we check up to the square root of a prime number to determine if it is prime?

Let's say m = sqrt(n) then m × m = n. Now if n is not a prime then n can be written as n = a × b, so m × m = a × b. Notice that m is a real number whereas n, a and b are natural numbers.

Now there can be 3 cases:

  1. a > m ? b < m
  2. a = m ? b = m
  3. a < m ? b > m

In all 3 cases, min(a, b) = m. Hence if we search till m, we are bound to find at least one factor of n, which is enough to show that n is not prime.

What exactly is Spring Framework for?

Basically Spring is a framework for which is a pattern that allows building very decoupled systems.

The problem

For example, suppose you need to list the users of the system and thus declare an interface called UserLister:

public interface UserLister {
    List<User> getUsers();

And maybe an implementation accessing a database to get all the users:

public class UserListerDB implements UserLister {
    public List<User> getUsers() {
        // DB access code here

In your view you'll need to access an instance (just an example, remember):

public class SomeView {
    private UserLister userLister;

    public void render() {
        List<User> users = userLister.getUsers();

Note that the code above hasn't initialized the variable userLister. What should we do? If I explicitly instantiate the object like this:

UserLister userLister = new UserListerDB();

...I'd couple the view with my implementation of the class that access the DB. What if I want to switch from the DB implementation to another that gets the user list from a comma-separated file (remember, it's an example)? In that case, I would go to my code again and change the above line to:

UserLister userLister = new UserListerCommaSeparatedFile();

This has no problem with a small program like this but... What happens in a program that has hundreds of views and a similar number of business classes? The maintenance becomes a nightmare!

Spring (Dependency Injection) approach

What Spring does is to wire the classes up by using an XML file or annotations, this way all the objects are instantiated and initialized by Spring and injected in the right places (Servlets, Web Frameworks, Business classes, DAOs, etc, etc, etc...).

Going back to the example in Spring we just need to have a setter for the userLister field and have either an XML file like this:

<bean id="userLister" class="UserListerDB" />

<bean class="SomeView">
    <property name="userLister" ref="userLister" />

or more simply annotate the filed in our view class with @Inject:

private UserLister userLister;

This way when the view is created it magically will have a UserLister ready to work.

List<User> users = userLister.getUsers();  // This will actually work
                                           // without adding any line of code

It is great! Isn't it?

  • What if you want to use another implementation of your UserLister interface? Just change the XML.
  • What if don't have a UserLister implementation ready? Program a temporal mock implementation of UserLister and ease the development of the view.
  • What if I don't want to use Spring anymore? Just don't use it! Your application isn't coupled to it. Inversion of Control states: "The application controls the framework, not the framework controls the application".

There are some other options for Dependency Injection around there, what in my opinion has made Spring so famous besides its simplicity, elegance and stability is that the guys of SpringSource have programmed many many POJOs that help to integrate Spring with many other common frameworks without being intrusive in your application. Also, Spring has several good subprojects like Spring MVC, Spring WebFlow, Spring Security and again a loooong list of etceteras.

Hope this helps. Anyway, I encourage you to read Martin Fowler's article about Dependency Injection and Inversion of Control because he does it better than me. After understanding the basics take a look at Spring Documentation, in my opinion, it is used to be the best Spring book ever.

FromBody string parameter is giving null

I just ran into this and was frustrating. My setup: The header was set to Content-Type: application/JSON and was passing the info from the body with JSON format, and was reading [FromBody] on the controller.

Everything was set up fine and I expect it to work, but the problem was with the JSON sent over. Since it was a complex structure, one of my classes which was defined 'Abstract' was not getting initialized and hence the values weren't assigned to the model properly. I removed the abstract keyword and it just worked..!!!

One tip, the way I could figure this out was to send data in parts to my controller and check when it becomes null... since it was a complex model I was appending one model at a time to my request params. Hope it helps someone who runs into this stupid issue.

What is the difference between #import and #include in Objective-C?

I know this thread is old... but in "modern times".. there is a far superior "include strategy" via clang's @import modules - that is oft-overlooked..

Modules improve access to the API of software libraries by replacing the textual preprocessor inclusion model with a more robust, more efficient semantic model. From the user’s perspective, the code looks only slightly different, because one uses an import declaration rather than a #include preprocessor directive:

@import Darwin; // Like including all of /usr/include. @see /usr/include/


@import Foundation;  //  Like #import <Foundation/Foundation.h>
@import ObjectiveC;  //  Like #import <objc/runtime.h>

However, this module import behaves quite differently from the corresponding #include: when the compiler sees the module import above, it loads a binary representation of the module and makes its API available to the application directly. Preprocessor definitions that precede the import declaration have no impact on the API provided... because the module itself was compiled as a separate, standalone module. Additionally, any linker flags required to use the module will automatically be provided when the module is imported. This semantic import model addresses many of the problems of the preprocessor inclusion model.

To enable modules, pass the command-line flag -fmodules aka CLANG_ENABLE_MODULES in Xcode- at compile time. As mentioned above.. this strategy obviates ANY and ALL LDFLAGS. As in, you can REMOVE any "OTHER_LDFLAGS" settings, as well as any "Linking" phases..

enter image description here

I find compile / launch times to "feel" much snappier (or possibly, there's just less of a lag while "linking"?).. and also, provides a great opportunity to purge the now extraneous Project-Prefix.pch file, and corresponding build settings, GCC_INCREASE_PRECOMPILED_HEADER_SHARING, GCC_PRECOMPILE_PREFIX_HEADER, and GCC_PREFIX_HEADER, etc.

Also, while not well-documented… You can create module.maps for your own frameworks and include them in the same convenient fashion. You can take a look at my ObjC-Clang-Modules github repo for some examples of how to implement such miracles.

Django -- Template tag in {% if %} block

Sorry for comment in an old post but if you want to use an else if statement this will help you

{% if title == source %}
    Do This
{% elif title == value %}
    Do This
{% else %}
    Do This
{% endif %}

For more info see Django Documentation

Saving data to a file in C#

Look into the XMLSerializer class.

If you want to save the state of objects and be able to recreate them easily at another time, serialization is your best bet.

Serialize it so you are returned the fully-formed XML. Write this to a file using the StreamWriter class.

Later, you can read in the contents of your file, and pass it to the serializer class along with an instance of the object you want to populate, and the serializer will take care of deserializing as well.

Here's a code snippet taken from Microsoft Support:

using System;

public class clsPerson
  public  string FirstName;
  public  string MI;
  public  string LastName;

class class1
   static void Main(string[] args)
      clsPerson p=new clsPerson();
      p.FirstName = "Jeff";
      p.MI = "A";
      p.LastName = "Price";
      System.Xml.Serialization.XmlSerializer x = new System.Xml.Serialization.XmlSerializer(p.GetType());

      // at this step, instead of passing Console.Out, you can pass in a 
      // Streamwriter to write the contents to a file of your choosing.
      x.Serialize(Console.Out, p);


Django optional url parameters

Even simpler is to use:


The "(a|b)" means a or b, so in your case it would be one or more word characters (\w+) or nothing.

So it would look like:


How do you define a class of constants in Java?

Aren't enums best choice for these kinds of stuff?

How to convert QString to std::string?

Try this:

#include <QDebug>
QString string;
// do things...
qDebug() << "right" << string << std::endl;

Find out whether radio button is checked with JQuery?

If you have a group of radio buttons sharing the same name attribute and upon submit or some event you want to check if one of these radio buttons was checked, you can do this simply by the following code :

  $('#submit_button').click(function() {
    if (!$("input[name='name']:checked").val()) {
       alert('Nothing is checked!');
        return false;
    else {
      alert('One of the radio buttons is checked!');


jQuery API Ref


You can return json in PHP this way:

header('Content-Type: application/json');
echo json_encode(array('foo' => 'bar'));

How to spawn a process and capture its STDOUT in .NET?

Redirecting the stream is asynchronous and will potentially continue after the process has terminated. It is mentioned by Umar to cancel after process termination process.CancelOutputRead(). However that has data loss potential.

This is working reliably for me:

while (process.StandardOutput.EndOfStream == false)

I didn't try this approach but I like the suggestion from Sly:

if (process.WaitForExit(timeout))

"Use of undeclared type" in Swift, even though type is internal, and exists in same module

Sometimes errors can be very silly

Before checking all the solutions up here , make sure you have imported all the basic stuff

     import Foundation
     import UIKit

It is quite a possibility that when you import some files from outside to your project, which may miss this basic things as I experienced once .

Java: how do I check if a Date is within a certain range?

Since Java 8

NOTE: All, but one, Date's constructors are deprecated. Most of the Date's methods are deprecated. REF: Date: Deprecated Methods. All, but Date::from(Instant), static methods are deprecated.

So, since java 8 consider using Instant (immutable, thread-safe, leap-seconds aware) type rather than Date. REF: Instant

  static final LocalTime MARKETS_OPEN = LocalTime.of(07, 00);
  static final LocalTime MARKETS_CLOSE = LocalTime.of(20, 00);

    // Instant utcTime = testDate.toInstant();
    var bigAppleTime = ZonedDateTime.ofInstant(utcTime, ZoneId.of("America/New_York"));

within the range INCLUSIVE:

    return !bigAppleTime.toLocalTime().isBefore(MARKETS_OPEN)
        && !bigAppleTime.toLocalTime().isAfter(MARKETS_CLOSE);

within the range EXCLUSIVE:

    return bigAppleTime.toLocalTime().isAfter(MARKETS_OPEN)
        && bigAppleTime.toLocalTime().isBefore(MARKETS_CLOSE);

Bootstrap carousel resizing image

Put the following code into head section in your web page programming.

  <style>.carousel-inner > .item > img { width:100%; height:570px; } </style>

Android - Center TextView Horizontally in LinearLayout

What's happening is that since the the TextView is filling the whole width of the inner LinearLayout it is already in the horizontal center of the layout. When you use android:layout_gravity it places the widget, as a whole, in the gravity specified. Instead of placing the whole widget center what you're really trying to do is place the content in the center which can be accomplished with android:gravity="center_horizontal" and the android:layout_gravity attribute can be removed.

CSS Cell Margin

<!DOCTYPE html>_x000D_
border-spacing: 16px 4px;_x000D_
 td {_x000D_
    border: 1px solid black;_x000D_
<table style="width:100%">_x000D_
    <td>Smith</td>  _x000D_
    <td>Jackson</td>  _x000D_
    <td>Doe</td>  _x000D_

Using padding is not correct way of doing it, it may change the look but it is not what you wanted. This may solve your issue.

.Net System.Mail.Message adding multiple "To" addresses

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Mail;
using System.Web;

namespace HMS.HtmlHelper
    public class SendmailHelper
        //Created SendEMail method for sendiing mails to users 
        public bool SendEMail(string FromName, string ToAddress, string Subject, string Message)
            bool valid =false;
                string smtpUserName = System.Configuration.ConfigurationManager.AppSettings["smtpusername"].ToString();
                string smtpPassword = System.Configuration.ConfigurationManager.AppSettings["smtppassword"].ToString();
                MailMessage mail = new MailMessage();``
                mail.From = new MailAddress(smtpUserName, FromName);
                mail.Subject = Subject;
                mail.Body = Message.ToString();
                mail.IsBodyHtml = true;
                SmtpClient smtp = new SmtpClient();
                smtp.Port = Convert.ToInt32(System.Configuration.ConfigurationManager.AppSettings["smtpserverport"]);
                smtp.Host = System.Configuration.ConfigurationManager.AppSettings["SmtpServer"]; /
                smtp.Credentials = new System.Net.NetworkCredential(smtpUserName, smtpPassword);
                smtp.EnableSsl = Convert.ToBoolean(System.Configuration.ConfigurationManager.AppSettings["ssl"]); ;
                valid = true;

            catch (Exception ex)
                valid =false ;

            return valid;

        public string FormatMultipleEmailAddresses(string emailAddresses)
            var delimiters = new[] { ',', ';' };

            var addresses = emailAddresses.Split(delimiters, StringSplitOptions.RemoveEmptyEntries);

            return string.Join(",", addresses);


What is the difference between Builder Design pattern and Factory Design pattern?

First some general things to follow my argumentation:

The main challenge in designing big software systems is that they have to be flexible and uncomplicated to change. For this reason, there are some metrics like coupling and cohesion. To achieve systems that can be easily altered or extended in its functionality without the need to redesign the whole system from scratch, you can follow the design principles (like SOLID, etc.). After a while some developer recognized that if they follow those principles there are some similar solutions that worked well to similar problems. Those standard solutions turned out to be the design patterns.

So the design patterns are to support you to follow the general design principles in order to achieve loosely coupled systems with high cohesion.

Answering the question:

By asking the difference between two patterns you have to ask yourself what pattern makes your system in which way more flexible. Each pattern has its own purpose to organize dependencies between classes in your system.

The Abstract Factory Pattern: GoF: “Provide an interface for creating families of related or dependent objects without specifying their concrete classes.”

What does this mean: By providing an interface like this the call to the constructor of each of the family’s product is encapsulated in the factory class. And because this is the only place in your whole system where those constructors are called you can alter your system by implementing a new factory class. If you exchange the representation of the factory through another, you can exchange a whole set of products without touching the majority of your code.

The Builder Pattern: GoF: “Separate the construction of a complex object from its representation so that the same construction process can create different representations.”

What does this mean: You encapsulate the process of construction in another class, called the director (GoF). This director contains the algorithm of creating new instances of the product (e.g. compose a complex product out of other parts). To create the integral parts of the whole product the director uses a builder. By exchanging the builder in the director you can use the same algorithm to create the product, but change the representations of single parts (and so the representation of the product). To extend or modify your system in the representation of the product, all you need to do is to implement a new builder class.

So in short: The Abstract Factory Pattern’s purpose is to exchange a set of products which are made to be used together. The Builder Pattern’s purpose is to encapsulate the abstract algorithm of creating a product to reuse it for different representations of the product.

In my opinion you can’t say that the Abstract Factory Pattern is the big brother of the Builder Pattern. YES, they are both creational patterns, but the main intent of the patterns is entirely different.

Jquery bind double click and single click separately

var singleClickTimer = 0; //define a var to hold timer event in parent scope{ //using jquery click handler
    if (e.detail == 1) { //ensure this is the first click
        singleClickTimer = setTimeout(function(){ //create a timer
            alert('single'); //run your single click code
        },250); //250 or 1/4th second is about right

jqueryElem.dblclick(function(e){ //using jquery dblclick handler
    clearTimeout(singleClickTimer); //cancel the single click
    alert('double'); //run your double click code

How can I find the OWNER of an object in Oracle?

You can query the ALL_OBJECTS view:

select owner
     , object_name
     , object_type
 where object_name = 'FOO'

To find synonyms:

select *
 where synonym_name = 'FOO'

Just to clarify, if a user user's SQL statement references an object name with no schema qualification (e.g. 'FOO'), Oracle FIRST checks the user's schema for an object of that name (including synonyms in that user's schema). If Oracle can't resolve the reference from the user's schema, Oracle then checks for a public synonym.

If you are looking specifically for constraints on a particular table_name:

select c.*
  from all_constraints c 
 where c.table_name = 'FOO'
 union all
select cs.*
  from all_constraints cs
  join all_synonyms s 
    on (s.table_name = cs.table_name
     and s.table_owner = cs.owner 
     and s.synonym_name = 'FOO'


-- addendum:

If your user is granted access to the DBA_ views (e.g. if your user has been granted SELECT_CATALOG_ROLE), you can substitute 'DBA_' in place of 'ALL_' in the preceding SQL examples. The ALL_x views only show objects which you have been granted privileges. The DBA_x views will show all database objects, whether you have privileges on them or not.

What are Keycloak's OAuth2 / OpenID Connect endpoints?


you will see everything here, plus if the identity provider is also Keycloak then feeding this URL will setup everything also true with other identity providers if they support and they already handled it

How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops

Expanding on patszim's answer for those in a rush.

  1. Open Excel workbook.
  2. Alt+F11 to open VBA/Macros window.
  3. Add reference to regex under Tools then References
    ![Excel VBA Form add references
  4. and selecting Microsoft VBScript Regular Expression 5.5
    ![Excel VBA add regex reference
  5. Insert a new module (code needs to reside in the module otherwise it doesn't work).
    ![Excel VBA insert code module
  6. In the newly inserted module,
    ![Excel VBA insert code into module
  7. add the following code:

    Function RegxFunc(strInput As String, regexPattern As String) As String
        Dim regEx As New RegExp
        With regEx
            .Global = True
            .MultiLine = True
            .IgnoreCase = False
            .pattern = regexPattern
        End With
        If regEx.Test(strInput) Then
            Set matches = regEx.Execute(strInput)
            RegxFunc = matches(0).Value
            RegxFunc = "not matched"
        End If
    End Function
  8. The regex pattern is placed in one of the cells and absolute referencing is used on it. ![Excel regex function in-cell usage Function will be tied to workbook that its created in.
    If there's a need for it to be used in different workbooks, store the function in Personal.XLSB

Overlaying a DIV On Top Of HTML 5 Video

Here's an example that will center the content within the parent div. This also makes sure the overlay starts at the edge of the video, even when centered.

<div class="outer-container">
    <div class="inner-container">
        <div class="video-overlay">Bug Buck Bunny - Trailer</div>
        <video id="player" src="" controls autoplay loop></video>

with css as

.outer-container {
    border: 1px dotted black;
    width: 100%;
    height: 100%;
    text-align: center;
.inner-container {
    border: 1px solid black;
    display: inline-block;
    position: relative;
.video-overlay {
    position: absolute;
    left: 0px;
    top: 0px;
    margin: 10px;
    padding: 5px 5px;
    font-size: 20px;
    font-family: Helvetica;
    color: #FFF;
    background-color: rgba(50, 50, 50, 0.3);
video {
    width: 100%;
    height: 100%;

here's the jsfiddle

Hope that helps :)

Python reading from a file and saving to utf-8

You can't do that using open. use codecs.

when you are opening a file in python using the open built-in function you will always read/write the file in ascii. To write it in utf-8 try this:

import codecs
file ='data.txt','w','utf-8')

Listen to port via a Java socket

Try this piece of code, rather than ObjectInputStream.

BufferedReader in = new BufferedReader (new InputStreamReader (socket.getInputStream ()));
while (true)
    String cominginText = "";
        cominginText = in.readLine ();
        System.out.println (cominginText);
    catch (IOException e)
        //error ("System: " + "Connection to server lost!");
        System.exit (1);

Python Progress Bar

Guess i'm a little late but this should work for people working with the current versions of python 3, since this uses "f-strings", as introduced in Python 3.6 PEP 498:


from numpy import interp

class Progress:
    def __init__(self, value, end, title='Downloading',buffer=20):
        self.title = title
        #when calling in a for loop it doesn't include the last number
        self.end = end -1
        self.buffer = buffer
        self.value = value

    def progress(self):
        maped = int(interp(self.value, [0, self.end], [0, self.buffer]))
        print(f'{self.title}: [{"#"*maped}{"-"*(self.buffer - maped)}]{self.value}/{self.end} {((self.value/self.end)*100):.2f}%', end='\r')


#some loop that does perfroms a task
for x in range(21)  #set to 21 to include until 20
    Progress(x, 21)


Downloading: [########------------] 8/20 40.00%

C# with MySQL INSERT parameters

What I did is like this.

String person;
String address;
person = your value;
address =your value;
string connString = ConfigurationManager.ConnectionStrings["default"].ConnectionString;
    MySqlConnection conn = new MySqlConnection(connString);
    MySqlCommand comm = conn.CreateCommand();
    comm.CommandText = "INSERT INTO room(person,address) VALUES('"+person+"','"+address+"')";

Python subprocess/Popen with a modified environment

you might use my_env.get("PATH", '') instead of my_env["PATH"] in case PATH somehow not defined in the original environment, but other than that it looks fine.

Reason: no suitable image found

You may still get this issue after tried @Jieyi Hu Answer. may it's seems fixed but if it's comes again (possibly on xCode 9).

However, this workaround seems to work (applies to Cocoapods 1.5.x):

  1. clean your project
  2. close Xcode and delete DerivedData
  3. open Podfile in your project , and add this:

    post_install do |installer| installer.pods_project.build_configurations.each do |config| config.build_settings.delete('CODE_SIGNING_ALLOWED') config.build_settings.delete('CODE_SIGNING_REQUIRED') end end

  4. pod update


Thank you @Cédric /storage/emulated/0/New file.txt: open failed: EACCES (Permission denied)

I suspect you are running Android 6.0 Marshmallow (API 23) or later. If this is the case, you must implement runtime permissions before you try to read/write external storage.

JavaScript ternary operator example with functions

Heh, there are some pretty exciting uses of ternary syntax in your question; I like the last one the best...

x = (1 < 2) ? true : false;

The use of ternary here is totally unnecessary - you could simply write

x = (1 < 2);

Likewise, the condition element of a ternary statement is always evaluated as a Boolean value, and therefore you can express:

(IsChecked == true) ? removeItem($this) : addItem($this);

Simply as:

(IsChecked) ? removeItem($this) : addItem($this);

In fact, I would also remove the IsChecked temporary as well which leaves you with:

($this.hasClass("IsChecked")) ? removeItem($this) : addItem($this);

As for whether this is acceptable syntax, it sure is! It's a great way to reduce four lines of code into one without impacting readability. The only word of advice I would give you is to avoid nesting multiple ternary statements on the same line (that way lies madness!)

How to get anchor text/href on click using jQuery?


Using the example from Sarfraz above.

<div class="res">
    <a class="info_link" href="~/Resumes/Resumes1271354404687.docx">

For href:

  $('.res').on('click', '.info_link', function(){

Cannot install signed apk to device manually, got error "App not installed"

In Android Studio 3.0 and Above

As described here

Note: The Run button builds an APK with testOnly="true", which means the APK can only be installed via adb (which Android Studio uses). If you want a debuggable APK that people can install without adb, select your debug variant and click Build Bundle(s) / APK(s) > Build APK(s).

Add android:testOnly="false" inside Application tag in AndroidManifest.xml


What good are SQL Server schemas?

If you keep your schema discrete then you can scale an application by deploying a given schema to a new DB server. (This assumes you have an application or system which is big enough to have distinct functionality).

An example, consider a system that performs logging. All logging tables and SPs are in the [logging] schema. Logging is a good example because it is rare (if ever) that other functionality in the system would overlap (that is join to) objects in the logging schema.

A hint for using this technique -- have a different connection string for each schema in your application / system. Then you deploy the schema elements to a new server and change your connection string when you need to scale.

How to search if dictionary value contains certain string with Python

>>> myDict
{'lastName': ['Stone', 'Lee'], 'age': ['12'], 'firstName': ['Alan', 'Mary-Ann'],
 'address': ['34 Main Street, 212 First Avenue']}

>>> Set = set()

>>> not ['' for Key, Values in myDict.items() for Value in Values if 'Mary' in Value and Set.add(Key)] and list(Set)

Convert an array to string

My suggestion:

using System.Linq;

string myStringOutput = String.Join(",", myArray.Select(p => p.ToString()).ToArray());


How to determine the first and last iteration in a foreach loop?

You can use the counter and array length.

    $array = array(1,2,3,4);

    $i = 0;
    $len = count($array);
    foreach ($array as $item) {
        if ($i === 0) {
            // first
        } else if ($i === $len - 1) {
            // last
        // …

How to call a function after delay in Kotlin?

A simple example to show a toast after 3 seconds :

fun onBtnClick() {
    val handler = Handler()
    handler.postDelayed({ showToast() }, 3000)

fun showToast(){
    Toast.makeText(context, "Its toast!", Toast.LENGTH_SHORT).show()

Using os.walk() to recursively traverse directories in Python

There are more suitable functions for this in os package. But if you have to use os.walk, here is what I come up with

def walkdir(dirname):
    for cur, _dirs, files in os.walk(dirname):
        pref = ''
        head, tail = os.path.split(cur)
        while head:
            pref += '---'
            head, _tail = os.path.split(head)
        for f in files:


>>> walkdir('.')

How to remove border from specific PrimeFaces p:panelGrid?

As mentioned by BalusC, the border is set by PrimeFaces on the generated tr and td elements, not on the table. However when trying with PrimeFaces version 5, it looks like there is a more specific match from the PrimeFaces CSS .ui-panelgrid .ui-panelgrid-cell > solid which still result in black borders being shown when appyling the style suggested.

Try using following style in order to overide the Primefaces one without using the !important declaration:

.companyHeaderGrid tr, .companyHeaderGrid td.ui-panelgrid-cell {
    border: none;

As mention make sure your CSS is loaded after the PrimeFaces one.

Which versions of SSL/TLS does System.Net.WebRequest support?

This is an important question. The SSL 3 protocol (1996) is irreparably broken by the Poodle attack published 2014. The IETF have published "SSLv3 MUST NOT be used". Web browsers are ditching it. Mozilla Firefox and Google Chrome have already done so.

Two excellent tools for checking protocol support in browsers are SSL Lab's client test and . The latter does not require Javascript, so you can try it from .NET's HttpClient:

// set proxy if you need to
// WebRequest.DefaultWebProxy = new WebProxy("http://localhost:3128");

File.WriteAllText("howsmyssl-httpclient.html", new HttpClient().GetStringAsync("").Result);

// alternative using WebClient for older framework versions
// new WebClient().DownloadFile("", "howsmyssl-webclient.html");

The result is damning:

Your client is using TLS 1.0, which is very old, possibly susceptible to the BEAST attack, and doesn't have the best cipher suites available on it. Additions like AES-GCM, and SHA256 to replace MD5-SHA-1 are unavailable to a TLS 1.0 client as well as many more modern cipher suites.

That's concerning. It's comparable to 2006's Internet Explorer 7.

To list exactly which protocols a HTTP client supports, you can try the version-specific test servers below:

var test_servers = new Dictionary<string, string>();
test_servers["SSL 2"] = "";
test_servers["SSL 3"] = "";
test_servers["TLS 1.0"] = "";
test_servers["TLS 1.1"] = "";
test_servers["TLS 1.2"] = "";

var supported = new Func<string, bool>(url =>
    try { return new HttpClient().GetAsync(url).Result.IsSuccessStatusCode; }
    catch { return false; }

var supported_protocols = test_servers.Where(server => supported(server.Value));
Console.WriteLine(string.Join(", ", supported_protocols.Select(x => x.Key)));

I'm using .NET Framework 4.6.2. I found HttpClient supports only SSL 3 and TLS 1.0. That's concerning. This is comparable to 2006's Internet Explorer 7.

Update: It turns HttpClient does support TLS 1.1 and 1.2, but you have to turn them on manually at System.Net.ServicePointManager.SecurityProtocol. See

I don't know why it uses bad protocols out-the-box. That seems a poor setup choice, tantamount to a major security bug (I bet plenty of applications don't change the default). How can we report it?

Difference Between $.getJSON() and $.ajax() in jQuery


data: { patientID: "1" },


data: "{ 'patientID': '1' }",

Further reading: 3 mistakes to avoid when using jQuery with ASP.NET

This Activity already has an action bar supplied by the window decor

It could also be because you have a style without a parent specified:

<style name="DarkModeTheme" >
    <item name="searchBarBgColor">#D6D6D6</item>

Remove it, and it should fix the problem.

Convert php array to Javascript

You do not have to call parseJSON since the output of json_encode is a javascript literal. Just assign it to a js variable.

<script type="text/javascript">
    //Assign php generated json to JavaScript variable
    var tempArray = <?php echo json_encode($php_array); ?>;

   //You will be able to access the properties as 

bower command not found

This turned out to NOT be a bower problem, though it showed up for me with bower.

It seems to be a node-which problem. If a file is in the path, but has the setuid/setgid bit set, which will not find it.

Here is a files with the s bit set: (unix 'which' will find it with no problems).

ls -al /usr/local/bin -rwxrwsr-- 110 root nmt 5535636 Jul 17 2012 git

Here is a node-which attempt:

> which.sync('git')
Error: not found: git

I change the permissions (chomd 755 git). Now node-which can find it.

> which.sync('git')

Hope this helps.

Filtering Pandas Dataframe using OR statement

From the docs:

Another common operation is the use of boolean vectors to filter the data. The operators are: | for or, & for and, and ~ for not. These must be grouped by using parentheses.


alldata_balance = alldata[(alldata[IBRD] !=0) | (alldata[IMF] !=0)]

How to add an image in the title bar using html?

it works

Add this inside your head tag

<link rel="shortcut icon" href="" />

jQuery javascript regex Replace <br> with \n

Not really anything to do with jQuery, but if you want to trim a pattern from a string, then use a regular expression:

<textarea id="ta0"></textarea>
<button onclick="
  var ta = document.getElementById('ta0');
  var text = 'some<br>text<br />to<br/>replace';
  var re = /<br *\/?>/gi;
  ta.value = text.replace(re, '\n');
">Add stuff to text area</button>