Programs & Examples On #Gwt gin

GIN brings automatic dependency injection to GWT client-side code.

Get a Windows Forms control by name in C#

Assuming you have Windows.Form Form1 as the parent form which owns the menu you've created. One of the form's attributes is named .Menu. If the menu was created programmatically, it should be the same, and it would be recognized as a menu and placed in the Menu attribute of the Form.

In this case, I had a main menu called File. A sub menu, called a MenuItem under File contained the tag Open and was named menu_File_Open. The following worked. Assuming you

// So you don't have to fully reference the objects.
using System.Windows.Forms;

// More stuff before the real code line, but irrelevant to this discussion.

MenuItem my_menuItem = (MenuItem)Form1.Menu.MenuItems["menu_File_Open"];

// Now you can do what you like with my_menuItem;

Android ImageView Zoom-in and Zoom-Out

I am Using this one it is working perfectly.


My a MyZoomableImageViewTouch class is below:

public class MyZoomableImageViewTouch extends ImageViewTouch

    static final float SCROLL_DELTA_THRESHOLD = 1.0f;

    public MyZoomableImageViewTouch(Context context, AttributeSet attrs, int defStyle)
        super(context, attrs, defStyle);

    public MyZoomableImageViewTouch(Context context, AttributeSet attrs) {
        super(context, attrs);

    public MyZoomableImageViewTouch(Context context)

    private void init() {
        View.OnTouchListener listener = new View.OnTouchListener() {
            public boolean onTouch(View v, MotionEvent event) {
                if (getScale() > 1f) {
                } else {
                return false;

    protected float onDoubleTapPost(float scale, float maxZoom) {
        if (scale != 1f) {
            mDoubleTapDirection = 1;
            return 1f;
        if (mDoubleTapDirection == 1) {
            mDoubleTapDirection = -1;
            if ((scale + (mScaleFactor * 2)) <= maxZoom) {
                return scale + mScaleFactor;
            } else {
                mDoubleTapDirection = -1;
                return maxZoom;
        } else {
            mDoubleTapDirection = 1;
            return 1f;

    public boolean canScroll(int direction) {
        RectF bitmapRect = getBitmapRect();
        updateRect(bitmapRect, mScrollRect);
        Rect imageViewRect = new Rect();

        if (null == bitmapRect) {
            return false;

        if (Math.abs(bitmapRect.right - imageViewRect.right) < SCROLL_DELTA_THRESHOLD) {
            if (direction < 0) {
                return false;

        if (Math.abs(bitmapRect.left - mScrollRect.left) < SCROLL_DELTA_THRESHOLD) {
            if (direction > 0) {
                return false;
        return true;

    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)
        if (getScale() == 1f) return false;
        if (distanceX != 0 && !canScroll((int) -distanceX)) {
            return false;
        } else {
            mUserScaled = true;
            scrollBy(-distanceX, -distanceY);
            return true;

Updating to latest version of CocoaPods?

I change the line "pod 'Alamofire', '~> 4.0'" to "pod 'Alamofire', :git => '', :commit => '3cc5b4e'" after that in terminal: "pod install --repo-update" and it works.

Difference between .keystore file and .jks file

One reason to choose .keystore over .jks is that Unity recognizes the former but not the latter when you're navigating to select your keystore file (Unity 2017.3, macOS).

Could not connect to Redis at Connection refused with homebrew

If after install you need to run redis on all time, just type in terminal:

redis-server &

Running redis using upstart on Ubuntu

I've been trying to understand how to setup systems from the ground up on Ubuntu. I just installed redis onto the box and here's how I did it and some things to look out for.

To install:

sudo apt-get install redis-server

That will create a redis user and install the init.d script for it. Since upstart is now the replacement for using init.d, I figure I should convert it to run using upstart.

To disable the default init.d script for redis:

sudo update-rc.d redis-server disable

Then create /etc/init/redis-server.conf with the following script:

description "redis server"

start on runlevel [23]
stop on shutdown

exec sudo -u redis /usr/bin/redis-server /etc/redis/redis.conf


What this is the script for upstart to know what command to run to start the process. The last line also tells upstart to keep trying to respawn if it dies.

One thing I had to change in /etc/redis/redis.conf is daemonize yes to daemonize no. What happens if you don't change it then redis-server will fork and daemonize itself, and the parent process goes away. When this happens, upstart thinks that the process has died/stopped and you won't have control over the process from within upstart.

Now you can use the following commands to control your redis-server:

sudo start redis-server
sudo restart redis-server
sudo stop redis-server

Hope this was helpful!

Lombok is not generating getter and setter

If you use STS. You must have Lombok installed in your Eclipse by running lombok-abc.jar

Please Following the Steps:

-Include pom in Maven . -Exit/Shutdown STS(must) -Find lombok Jar in ~.m2\repository\org\projectlombok\lombok\1.18.12 -From Command enter image description here

After then enter image description here

After then select the STS.exe enter image description here

After then click to update/update

enter image description here

then Quit Installer

Happy Coding


Iterate through Nested JavaScript Objects

I made a pick method like lodash pick. It is not exactly good like lodash _.pick, but you can pick any property event any nested property.

  • You just have to pass your object as a first argument then an array of properties in which you want to get their value as a second argument.

for example:

let car = { name: 'BMW', meta: { model: 2018, color: 'white'};
pick(car,['name','model']) // Output will be {name: 'BMW', model: 2018}

Code :

const pick = (object, props) => {
  let newObject = {};
  if (isObjectEmpty(object)) return {}; // Object.keys(object).length <= 0;

  for (let i = 0; i < props.length; i++) {
    Object.keys(object).forEach(key => {
      if (key === props[i] && object.hasOwnProperty(props[i])) {
        newObject[key] = object[key];
      } else if (typeof object[key] === "object") {
        Object.assign(newObject, pick(object[key], [props[i]]));
  return newObject;

function isObjectEmpty(obj) {
  for (let key in obj) {
    if (obj.hasOwnProperty(key)) return false;
  return true;
export default pick;

and here is the link to live example with unit tests

How to read a configuration file in Java

It depends.

Start with Basic I/O, take a look at Properties, take a look at Preferences API and maybe even Java API for XML Processing and Java Architecture for XML Binding

And if none of those meet your particular needs, you could even look at using some kind of Database

Create a zip file and download it

but the file i am getting from server after download it gives the size of 226 bytes

This is the size of a ZIP header. Apparently there is no data in the downloaded ZIP file. So, can you verify that the files to be added into the ZIP file are, indeed, there (relative to the path of the download PHP script)?

Consider adding a check on addFile too:

foreach($file_names as $file)
    $inputFile = $file_path . $file;
    if (!file_exists($inputFile))
        trigger_error("The input file $inputFile does not exist", E_USER_ERROR);
    if (!is_readable($inputFile))
        trigger_error("The input file $inputFile exists, but has wrong permissions or ownership", E_USER_ERROR);
    if (!$zip->addFile($inputFile, $file))
        trigger_error("Could not add $inputFile to ZIP file", E_USER_ERROR);

The observed behaviour is consistent with some problem (path error, permission problems, ...) preventing the files from being added to the ZIP file. On receiving an "empty" ZIP file, the client issues an error referring to the ZIP central directory missing (the actual error being that there is no directory, and no files).

Display more Text in fullcalendar

I would recommend the use of the eventAfterRender callback instead of eventRender. Indeed if you use eventRender you might jeopardize the correct display of the events, in coffee script, it something like :

    eventAfterRender: (event, element) ->

how to fetch data from database in Hibernate

I know that it is very late to answer the question, but it may help someone like me who spent lots off time to fetch data using hql

So the thing is you just have to write a query

Query query = session.createQuery("from Employee");

it will give you all the data list but to fetch data from this you have to write this line.

List<Employee> fetchedData = query.list();

As simple as it looks.

How can I reload .emacs after changing it?

Here is a quick and easy way to quick test your config. You can also use C-x C-e at the end of specific lisp to execute certain function individually.

C-x C-e runs the command eval-last-sexp (found in global-map), which is an interactive compiled Lisp function.

It is bound to C-x C-e.


Evaluate sexp before point; print value in the echo area. Interactively, with prefix argument, print output into current buffer.

Normally, this function truncates long output according to the value of the variables ‘eval-expression-print-length’ and ‘eval-expression-print-level’. With a prefix argument of zero, however, there is no such truncation. Such a prefix argument also causes integers to be printed in several additional formats (octal, hexadecimal, and character).

If ‘eval-expression-debug-on-error’ is non-nil, which is the default, this command arranges for all errors to enter the debugger.

How can I make a TextBox be a "password box" and display stars when using MVVM?

You can make your TextBox as customed PasswordBox by simply adding the following value to FontFamily property of your TextBox control.

    Text="{Binding Password}"

In my case this works perfectly. This will show dot in place of the actual text (not star(*) though).

How to get df linux command output always in GB

If you also want it to be a command you can reference without remembering the arguments, you could simply alias it:

alias df-gb='df -BG'

So if you type:


into a terminal, you'll get your intended output of the disk usage in GB.

EDIT: or even use just df -h to get it in a standard, human readable format.

How to get the cursor to change to the hand when hovering a <button> tag

 #more {
    font-family:Verdana, Geneva, sans-serif;
    cursor: pointer;

What does bundle exec rake mean?

When you directly run the rake task or execute any binary file of a gem, there is no guarantee that the command will behave as expected. Because it might happen that you already have the same gem installed on your system which have a version say 1.0 but in your project you have higher version say 2.0. In this case you can not predict which one will be used.

To enforce the desired gem version you take the help of bundle exec command which would execute the binary in context of current bundle. That means when you use bundle exec, bundler checks the gem version configured for the current project and use that to perform the task.

I have also written a post about it which also shows how we can avoid using it using bin stubs.

Get values from other sheet using VBA

Try the worksheet activate command before you need data from the sheet:


Regex for password must contain at least eight characters, at least one number and both lower and uppercase letters and special characters

Try this one:

  1. Minimum six characters
  2. At least one uppercase character
  3. At least one lowercase character
  4. At least one special character


"/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&.])[A-Za-z\d$@$!%*?&.]{6, 20}/"

Optional Special Characters:

  1. At least one special character
  2. At least one number
  3. Special characters are optional
  4. Minimum six characters and maximum 16 characters



If the min and max condition is not required then remove .{6, 16}

  • 6 is minimum character limit
  • 20 is maximum character limit
  • ?= means match expression

Calling startActivity() from outside of an Activity?

In my case I have used context for startActivity, after changing that with ActivityName.this . it solves. I'm using method from util class so this happens.

Hope it help some one.

Create File If File Does Not Exist


using FileStream fileStream = File.Open(path, FileMode.Append);
using StreamWriter file = new StreamWriter(fileStream);
// ...

How to check if a variable is both null and /or undefined in JavaScript

You can wrap it in your own function:

function isNullAndUndef(variable) {

    return (variable !== null && variable !== undefined);

How to iterate through range of Dates in Java?

This will help you start 30 days back and loop through until today's date. you can easily change range of dates and direction.

private void iterateThroughDates() throws Exception {
    Calendar start = Calendar.getInstance();
    start.add(Calendar.DATE, -30);
    Calendar end = Calendar.getInstance();
    for (Calendar date = start; date.before(end); date.add(Calendar.DATE, 1))

Is it possible to make Font Awesome icons larger than 'fa-5x'?

Alternatively you can edit the source and create your own incrementations

FontAwesome 5

// Icon Sizes
// -------------------------

.larger(@factor) when (@factor > 0) {
  .larger((@factor - 1));

  .@{fa-css-prefix}-@{factor}x {
    font-size: (@factor * 1em);

/* makes the font 33% larger relative to the icon container */
.@{fa-css-prefix}-lg {
  font-size: (4em / 3);
  line-height: (3em / 4);
  vertical-align: -.0667em;

.@{fa-css-prefix}-xs {
  font-size: .75em;

.@{fa-css-prefix}-sm {
  font-size: .875em;

// Change the number below to create your own incrementations
// This currently creates classes .fa-1x - .fa-10x

FontAwesome 4

// Icon Sizes
// -------------------------

/* makes the font 33% larger relative to the icon container */
.@{fa-css-prefix}-lg {
    font-size: (4em / 3);
    line-height: (3em / 4);
    vertical-align: -15%;

.@{fa-css-prefix}-2x { font-size: 2em; }
.@{fa-css-prefix}-3x { font-size: 3em; }
.@{fa-css-prefix}-4x { font-size: 4em; }
.@{fa-css-prefix}-5x { font-size: 5em; }

// Your custom sizes
.@{fa-css-prefix}-6x { font-size: 6em; }
.@{fa-css-prefix}-7x { font-size: 7em; }
.@{fa-css-prefix}-8x { font-size: 8em; }

Switch with if, else if, else, and loops inside case

but i only wanted the for statement to be attached to the if statement, not the else if statements as well.

Well get rid of the else then. If the else if is not supposed to be part of the for then write it as:

           for(int i=0; i<something_in_the_array.length;i++)

                break;  // redundant now

           else if(whatever_value==3)
                break;  // redundant now

Having said that:

  • it is not at all clear what you are really trying to do here,
  • not having the else part in the loop doesn't seem to make a lot of sense here,
  • a lot of people (myself included) think it is to always use braces ... so that people don't get tripped up by incorrect indentation when reading your code. (And in this case, it might help us figure out what you are really trying to do here ...)

Finally, braces are less obtrusive if you put the opening brace on the end of the previous line; e.g.

  if (something) {

rather than:

  if (something) 

ActiveXObject creation error " Automation server can't create object"

This error is cause by security clutches between the web application and your java. To resolve it, look into your java setting under control panel. Move the security level to a medium.

Populating spinner directly in the layout xml

I'm not sure about this, but give it a shot.

In your strings.xml define:

<string-array name="array_name">
<item>Array Item One</item>
<item>Array Item Two</item>
<item>Array Item Three</item>

In your layout:


I've heard this doesn't always work on the designer, but it compiles fine.

How can I stop redis-server?

redis-cli shutdown is most effective. The accepted answer does not work for me (OSX Lion). Thanks, @JesseBuesking.

Fast way to discover the row count of a table in PostgreSQL

You can get the count by the below query (without * or any column names).

select from table_name;

Is it not possible to stringify an Error using JSON.stringify?

I was working on a JSON format for log appenders and ended up here trying to solve a similar problem. After a while, I realized I could just make Node do the work:

const util = require("util");
return JSON.stringify(obj, (name, value) => {
    if (value instanceof Error) {
        return util.format(value);
    } else {
        return value;

Dynamic type languages versus static type languages

It is all about the right tool for the job. Neither is better 100% of the time. Both systems were created by man and have flaws. Sorry, but we suck and making perfect stuff.

I like dynamic typing because it gets out of my way, but yes runtime errors can creep up that I didn't plan for. Where as static typing may fix the aforementioned errors, but drive a novice(in typed languages) programmer crazy trying to cast between a constant char and a string.

How to escape double quotes in JSON

if you want to escape double quote in JSON use \\ to escape it.

example if you want to create json of following javascript object

{time: '7 "o" clock'}

then you must write in following way

'{"time":"7 \\"o\\" clock"}'

if we parse it using JSON.parse()

JSON.parse('{"time":"7 \\"o\\" clock"}')

result will be

{time: "7 "o" clock"}

Running a shell script through Cygwin on Windows

The existing answers all seem to run this script in a DOS console window.

This may be acceptable, but for example means that colour codes (changing text colour) don't work but instead get printed out as they are:

there is no item "[032mGroovy[0m"

I found this solution some time ago, so I'm not sure whether mintty.exe is a standard Cygwin utility or whether you have to run the setup program to get it, but I run like this:

D:\apps\cygwin64\bin\mintty.exe -i /Cygwin-Terminal.ico  bash.exe .\

... this causes the script to run in a Cygwin BASH console instead of a Windows DOS console.

How to break lines at a specific character in Notepad++?

  1. Click Ctrl + h or Search -> Replace on the top menu
  2. Under the Search Mode group, select Regular expression
  3. In the Find what text field, type ],\s*
  4. In the Replace with text field, type ],\n
  5. Click Replace All

Python list directory, subdirectory, and files

Here is a one-liner:

import os

[val for sublist in [[os.path.join(i[0], j) for j in i[2]] for i in os.walk('./')] for val in sublist]
# Meta comment to ease selecting text

The outer most val for sublist in ... loop flattens the list to be one dimensional. The j loop collects a list of every file basename and joins it to the current path. Finally, the i loop iterates over all directories and sub directories.

This example uses the hard-coded path ./ in the os.walk(...) call, you can supplement any path string you like.

Note: os.path.expanduser and/or os.path.expandvars can be used for paths strings like ~/

Extending this example:

Its easy to add in file basename tests and directoryname tests.

For Example, testing for *.jpg files:

... for j in i[2] if j.endswith('.jpg')] ...

Additionally, excluding the .git directory:

... for i in os.walk('./') if '.git' not in i[0].split('/')]

Simple and fast method to compare images for similarity

Can the screenshot or icon be transformed (scaled, rotated, skewed ...)? There are quite a few methods on top of my head that could possibly help you:

  • Simple euclidean distance as mentioned by @carlosdc (doesn't work with transformed images and you need a threshold).
  • (Normalized) Cross Correlation - a simple metrics which you can use for comparison of image areas. It's more robust than the simple euclidean distance but doesn't work on transformed images and you will again need a threshold.
  • Histogram comparison - if you use normalized histograms, this method works well and is not affected by affine transforms. The problem is determining the correct threshold. It is also very sensitive to color changes (brightness, contrast etc.). You can combine it with the previous two.
  • Detectors of salient points/areas - such as MSER (Maximally Stable Extremal Regions), SURF or SIFT. These are very robust algorithms and they might be too complicated for your simple task. Good thing is that you do not have to have an exact area with only one icon, these detectors are powerful enough to find the right match. A nice evaluation of these methods is in this paper: Local invariant feature detectors: a survey.

Most of these are already implemented in OpenCV - see for example the cvMatchTemplate method (uses histogram matching): The salient point/area detectors are also available - see OpenCV Feature Detection.

Remove an entire column from a data.frame in R

You can set it to NULL.

> Data$genome <- NULL
> head(Data)
   chr region
1 chr1    CDS
2 chr1   exon
3 chr1    CDS
4 chr1   exon
5 chr1    CDS
6 chr1   exon

As pointed out in the comments, here are some other possibilities:

Data[2] <- NULL    # Wojciech Sobala
Data[[2]] <- NULL  # same as above
Data <- Data[,-2]  # Ian Fellows
Data <- Data[-2]   # same as above

You can remove multiple columns via:

Data[1:2] <- list(NULL)  # Marek
Data[1:2] <- NULL        # does not work!

Be careful with matrix-subsetting though, as you can end up with a vector:

Data <- Data[,-(2:3)]             # vector
Data <- Data[,-(2:3),drop=FALSE]  # still a data.frame

set the width of select2 input (through Angular-ui directive)

add method container css in your script like this :

      containerCss : {"display":"block"}

it will set your select's width same as width your div.

How to disable copy/paste from/to EditText

If you want to disable ActionMode for copy/pasting, you need to override 2 callbacks. This works for both TextView and EditText (or TextInputEditText)

import android.view.ActionMode

fun TextView.disableCopyPaste() {
  isLongClickable = false
  customSelectionActionModeCallback = object : ActionMode.Callback {
    override fun onCreateActionMode(mode: ActionMode?, menu: Menu) = false
    override fun onPrepareActionMode(mode: ActionMode?, menu: Menu) = false
    override fun onActionItemClicked(mode: ActionMode?, item: MenuItem) = false
    override fun onDestroyActionMode(mode: ActionMode?) {}
  //disable action mode when edittext gain focus at first
    customInsertionActionModeCallback = object : ActionMode.Callback {
      override fun onCreateActionMode(mode: ActionMode?, menu: Menu) = false
      override fun onPrepareActionMode(mode: ActionMode?, menu: Menu) = false
      override fun onActionItemClicked(mode: ActionMode?, item: MenuItem) = false
      override fun onDestroyActionMode(mode: ActionMode?) {}

This extension is based off above @Alexandr solution and worked fine for me.

How to resolve Error listenerStart when deploying web-app in Tomcat 5.5?

I encountered this error when the JDK that I compiled the app under was different from the tomcat JVM. I verified that the Tomcat manager was running jvm 1.6.0 but the app was compiled under java 1.7.0.

After upgrading Java and changing JAVA_HOME in our startup script (/etc/init.d/tomcat) the error went away.

CSS Background Opacity

You can use CSS 3 :before to have a semi-transparent background and you can do this with just one container. Use something like this


Then apply some CSS

article {
  position: relative;
  z-index: 1;

article::before {
  content: "";
  position: absolute;
  top: 0; 
  left: 0;
  width: 100%; 
  height: 100%;  
  opacity: .4; 
  z-index: -1;
  background: url(path/to/your/image);


Note: You might need to adjust the z-index values.

Escape text for HTML

Didn't see this here

System.Web.HttpUtility.JavaScriptStringEncode("Hello, this is Satan's Site")

it was the only thing that worked (asp 4.0+) when dealing with html like this. The&apos; gets rendered as ' (using htmldecode) in the html, causing it to fail:

<a href="article.aspx?id=268" onclick="'modules/xxx/id/268', 'It&apos;s Allstars'); return false;">It's Allstars</a>

How to change the color of an image on hover

If I understand correctly then it would be easier if you gave your image a transparent background and set the background container's background-color property without having to use filters and so on.

Shows you how to use filters in IE. Maybe if you leverage something from that. Not very cross-browser compatible though. Another option might be to have two images and use them as background-images (rather than img tags), swap one out after another using the :hover pseudo selector.

AngularJS $resource RESTful example

$resource was meant to retrieve data from an endpoint, manipulate it and send it back. You've got some of that in there, but you're not really leveraging it for what it was made to do.

It's fine to have custom methods on your resource, but you don't want to miss out on the cool features it comes with OOTB.

EDIT: I don't think I explained this well enough originally, but $resource does some funky stuff with returns. Todo.get() and Todo.query() both return the resource object, and pass it into the callback for when the get completes. It does some fancy stuff with promises behind the scenes that mean you can call $save() before the get() callback actually fires, and it will wait. It's probably best just to deal with your resource inside of a promise then() or the callback method.

Standard use

var Todo = $resource('/api/1/todo/:id');

//create a todo
var todo1 = new Todo(); = 'bar';
todo1.something = 123;

//get and update a todo
var todo2 = Todo.get({id: 123}); += '!';

//which is basically the same as...
Todo.get({id: 123}, function(todo) { += '!';

//get a list of todos
Todo.query(function(todos) {
  //do something with todos
  angular.forEach(todos, function(todo) { += ' something';

//delete a todo
Todo.$delete({id: 123});

Likewise, in the case of what you posted in the OP, you could get a resource object and then call any of your custom functions on it (theoretically):

var something = src.GetTodo({id: 123}); = 'hi there';

I'd experiment with the OOTB implementation before I went and invented my own however. And if you find you're not using any of the default features of $resource, you should probably just be using $http on it's own.

Update: Angular 1.2 and Promises

As of Angular 1.2, resources support promises. But they didn't change the rest of the behavior.

To leverage promises with $resource, you need to use the $promise property on the returned value.

Example using promises

var Todo = $resource('/api/1/todo/:id');

Todo.get({id: 123}).$promise.then(function(todo) {
   // success
   $scope.todos = todos;
}, function(errResponse) {
   // fail

Todo.query().$promise.then(function(todos) {
   // success
   $scope.todos = todos;
}, function(errResponse) {
   // fail

Just keep in mind that the $promise property is a property on the same values it was returning above. So you can get weird:

These are equivalent

var todo = Todo.get({id: 123}, function() {
   $scope.todo = todo;

Todo.get({id: 123}, function(todo) {
   $scope.todo = todo;

Todo.get({id: 123}).$promise.then(function(todo) {
   $scope.todo = todo;

var todo = Todo.get({id: 123});
todo.$promise.then(function() {
   $scope.todo = todo;

Warning about `$HTTP_RAW_POST_DATA` being deprecated

If the .htaccess file not avilable create it on root folder and past this line of code.

Put this in .htaccess file (tested working well for API)

<IfModule mod_php5.c>
    php_value always_populate_raw_post_data -1

Trigger Change event when the Input value changed programmatically?

Vanilla JS solution:

var el = document.getElementById('changeProgramatic');
el.value='New Value'
el.dispatchEvent(new Event('change'));

Note that dispatchEvent doesn't work in old IE (see: caniuse). So you should probably only use it on internal websites (not on websites having wide audience).

So as of 2019 you just might want to make sure your customers/audience don't use Windows XP (yes, some still do in 2019). You might want to use conditional comments to warn customers that you don't support old IE (pre IE 11 in this case), but note that conditional comments only work until IE9 (don't work in IE10). So you might want to use feature detection instead. E.g. you could do an early check for: typeof document.body.dispatchEvent === 'function'.

Imported a csv-dataset to R but the values becomes factors

You can set this globally for all read.csv/read.* commands with options(stringsAsFactors=F)

Then read the file as follows: <- read.table( "filename.csv", )

Make a link in the Android browser start up my app?

Just want to open the app through browser? You can achieve it using below code:


<a href="intent:#Intent;action=packageName;category=android.intent.category.DEFAULT;category=android.intent.category.BROWSABLE;end">Click here</a>


      <action android:name="packageName" />
      <category android:name="android.intent.category.DEFAULT" />
      <category android:name="android.intent.category.BROWSABLE" />

This intent filter should be in Launcher Activity.

If you want to pass the data on click of browser link, just refer this link.

Understanding offsetWidth, clientWidth, scrollWidth and -Height, respectively

The CSS box model is rather complicated, particularly when it comes to scrolling content. While the browser uses the values from your CSS to draw boxes, determining all the dimensions using JS is not straight-forward if you only have the CSS.

That's why each element has six DOM properties for your convenience: offsetWidth, offsetHeight, clientWidth, clientHeight, scrollWidth and scrollHeight. These are read-only attributes representing the current visual layout, and all of them are integers (thus possibly subject to rounding errors).

Let's go through them in detail:

  • offsetWidth, offsetHeight: The size of the visual box incuding all borders. Can be calculated by adding width/height and paddings and borders, if the element has display: block
  • clientWidth, clientHeight: The visual portion of the box content, not including borders or scroll bars , but includes padding . Can not be calculated directly from CSS, depends on the system's scroll bar size.
  • scrollWidth, scrollHeight: The size of all of the box's content, including the parts that are currently hidden outside the scrolling area. Can not be calculated directly from CSS, depends on the content.

CSS2 Box Model

Try it out: jsFiddle

Since offsetWidth takes the scroll bar width into account, we can use it to calculate the scroll bar width via the formula

scrollbarWidth = offsetWidth - clientWidth - getComputedStyle().borderLeftWidth - getComputedStyle().borderRightWidth

Unfortunately, we may get rounding errors, since offsetWidth and clientWidth are always integers, while the actual sizes may be fractional with zoom levels other than 1.

Note that this

scrollbarWidth = getComputedStyle().width + getComputedStyle().paddingLeft + getComputedStyle().paddingRight - clientWidth

does not work reliably in Chrome, since Chrome returns width with scrollbar already substracted. (Also, Chrome renders paddingBottom to the bottom of the scroll content, while other browsers don't)

Read and write into a file using VBScript

Don't think can only use openTextFile for reading (1), writing (2), or appending (8). Reference here.

If you were using VB6 instead of VBScript, you could do:

Open "Filename" [For Mode] [AccessRestriction] [LockType] As #FileNumber

Using the Random mode. For example:

Open "C:\New\maddy.txt" For Random As #1

How to ignore a particular directory or file for tslint?

As an addition

To disable all rules for the next line // tslint:disable-next-line

To disable specific rules for the next line: // tslint:disable-next-line:rule1 rule2...

To disable all rules for the current line: someCode(); // tslint:disable-line

To disable specific rules for the current line: someCode(); // tslint:disable-line:rule1

How can I echo a newline in a batch file?

echo hello &

This means you could define & echo. as a constant for a newline \n.

TypeError: can't pickle _thread.lock objects

I had the same problem with Pool() in Python 3.6.3.

Error received: TypeError: can't pickle _thread.RLock objects

Let's say we want to add some number num_to_add to each element of some list num_list in parallel. The code is schematically like this:

class DataGenerator:
    def __init__(self, num_list, num_to_add)
        self.num_list = num_list # e.g. [4,2,5,7]
        self.num_to_add = num_to_add # e.g. 1 

    def run(self):
        new_num_list = Manager().list()

        pool = Pool(processes=50)
        results = [pool.apply_async(run_parallel, (num, new_num_list)) 
                      for num in num_list]
        roots = [r.get() for r in results]

    def run_parallel(self, num, shared_new_num_list):
        new_num = num + self.num_to_add # uses class parameter

The problem here is that self in function run_parallel() can't be pickled as it is a class instance. Moving this parallelized function run_parallel() out of the class helped. But it's not the best solution as this function probably needs to use class parameters like self.num_to_add and then you have to pass it as an argument.


def run_parallel(num, shared_new_num_list, to_add): # to_add is passed as an argument
    new_num = num + to_add

class DataGenerator:
    def __init__(self, num_list, num_to_add)
        self.num_list = num_list # e.g. [4,2,5,7]
        self.num_to_add = num_to_add # e.g. 1

    def run(self):
        new_num_list = Manager().list()

        pool = Pool(processes=50)
        results = [pool.apply_async(run_parallel, (num, new_num_list, self.num_to_add)) # num_to_add is passed as an argument
                      for num in num_list]
        roots = [r.get() for r in results]

Other suggestions above didn't help me.

Unknown Column In Where Clause

See the following MySQL manual page:

"A select_expr can be given an alias using AS alias_name. The alias is used as the expression's column name and can be used in GROUP BY, ORDER BY, or HAVING clauses."


It is not permissible to refer to a column alias in a WHERE clause, because the column value might not yet be determined when the WHERE clause is executed. See Section B.5.4.4, “Problems with Column Aliases”.

Does Java read integers in little endian or big endian?

There's no way this could influence anything in Java, since there's no (direct non-API) way to map some bytes directly into an int in Java.

Every API that does this or something similar defines the behaviour pretty precisely, so you should look up the documentation of that API.

How to set image name in Dockerfile?

Here is another version if you have to reference a specific docker file:

version: "3"
    container_name: nginx
      context: ../..
      dockerfile: ./docker/nginx/Dockerfile
    image: my_nginx:latest

Then you just run

docker-compose build

Center a column using Twitter Bootstrap 3

Use mx-auto in your div class using Bootstrap 4.

<div class="container">
  <div class="row">
    <div class="mx-auto">
      You content here

How to allow CORS in react.js?

Suppose you want to hit https://yourwebsitedomain/app/getNames from http://localhost:3000 then just make the following changes:

packagae.json :

   "name": "version-compare-app",
   "proxy": "https://yourwebsitedomain/",
   "dependencies": {
    "@testing-library/jest-dom": "^4.2.4",
    "@testing-library/react": "^9.5.0",

In your component use it as follows:

import axios from "axios";

componentDidMount() {
const getNameUrl =

axios.get(getChallenge).then(data => {


Stop your local server and re run npm start. You should be able to see the data in browser's console logged

How to write to files using utl_file in oracle

Here is a robust function for using UTL_File.putline that includes the necessary error handling. It also handles headers, footers and a few other exceptional cases.

PROCEDURE usp_OUTPUT_ToFileAscii(p_Path IN VARCHAR2, p_FileName IN VARCHAR2, p_Input IN refCursor, p_Header in VARCHAR2, p_Footer IN VARCHAR2, p_WriteMode VARCHAR2) IS

              vLine VARCHAR2(30000);
              vFile UTL_FILE.file_type; 
              vExists boolean;
              vLength number;
              vBlockSize number;

        UTL_FILE.fgetattr(p_path, p_FileName, vExists, vLength, vBlockSize);

                 FETCH p_Input INTO vLine;
         IF p_input%ROWCOUNT > 0
            IF vExists THEN
               vFile := UTL_FILE.FOPEN_NCHAR(p_Path, p_FileName, p_WriteMode);
               --even if the append flag is passed if the file doesn't exist open it with W.
                vFile := UTL_FILE.FOPEN(p_Path, p_FileName, 'W');
            END IF;
            --GET HANDLE TO FILE
            IF p_Header IS NOT NULL THEN 
              UTL_FILE.PUT_LINE(vFile, p_Header);
            END IF;
            UTL_FILE.PUT_LINE(vFile, vLine);
            DBMS_OUTPUT.PUT_LINE('Record count > 0');

                FETCH p_Input INTO vLine;

                EXIT WHEN p_Input%NOTFOUND;

                UTL_FILE.PUT_LINE(vFile, vLine);

             END LOOP;

             IF p_Footer IS NOT NULL THEN 
                UTL_FILE.PUT_LINE(vFile, p_Footer);
             END IF;

             CLOSE p_Input;
          DBMS_OUTPUT.PUT_LINE('Record count = 0');

        END IF; 

           DBMS_OUTPUT.PUT_LINE ('invalid_path'); 

           DBMS_OUTPUT.PUT_LINE ('invalid_mode'); 

           DBMS_OUTPUT.PUT_LINE ('invalid_filehandle'); 

           DBMS_OUTPUT.PUT_LINE ('invalid_operation'); 

           DBMS_OUTPUT.PUT_LINE ('read_error');

          DBMS_OUTPUT.PUT_LINE ('write_error'); 

          DBMS_OUTPUT.PUT_LINE ('internal_error'); 
          DBMS_OUTPUT.PUT_LINE ('other write error'); 

How to set default value for form field in Symfony2?

Don't use:

'data' => 'Default value'

Read here:

"The data option always overrides the value taken from the domain data (object) when rendering. This means the object value is also overriden when the form edits an already persisted object, causing it to lose its persisted value when the form is submitted."

Use the following:

Lets say, for this example, you have an Entity Foo, and there is a field "active" (in this example is CheckBoxType, but process is the same to every other type), which you want to be checked by default

In your FooFormType class add:

use Symfony\Component\Form\FormEvent;
use Symfony\Component\Form\FormEvents;
public function buildForm( FormBuilderInterface $builder, array $options )

    $builder->add('active', CheckboxType::class, array(
        'label' => 'Active',

        function(FormEvent $event){                 
            $foo = $event->getData();
            // Set Active to true (checked) if form is "create new" ($foo->active = null)
            if(is_null($foo->getActive())) $foo->setActive(true);
public function configureOptions( OptionsResolver $resolver )
        'data_class' => 'AppBundle:Foo',

Toggle display:none style with JavaScript

You can do this through straight javascript and DOM, but I really recommend learning JQuery. Here is a function you can use to actually toggle that object.

EDIT: Adding the actual code:


HTML snippet:

<a href="#" id="showAll" title="Show Tags">Show All Tags</a>
<ul id="tags" class="subforums" style="display:none;overflow-x: visible; overflow-y: visible; ">
    <li>Tag 1</li>
    <li>Tag 2</li>
    <li>Tag 3</li>
    <li>Tag 4</li>
    <li>Tag 5</li>

Javascript code using JQuery from Google's Content Distribution Network:

$(function() {
    $('#showAll').click(function(){  //Adds click event listener  
        $('#tags').toggle('slow'); // Toggles visibility.  Use the 'slow' parameter to add a nice effect.

You can test directly from this link:

Additional Comments on JQuery:

Someone has suggested that using JQuery for something like this is wrong because it is a 50k Library. I have a strong opinion against that.

JQuery is widely used because of the huge advantages it offers (like many other javascript frameworks). Additionally, JQuery is hosted by Content Distribution Networks (CDNs) like Google's CDN that will guarantee that the library is cached in the client's browser. It will have minimal impact on the client.

Additionally, with JQuery you can use powerful selectors, adding event listener, and use functions that are for the most part guaranteed to be cross-browser.

If you are a beginner and want to learn Javascript, please don't discount frameworks like JQuery. It will make your life so much easier.

Ruby, remove last N characters from a string?

if you are using rails, try:

"my_string".last(2) # => "ng"


To get the string WITHOUT the last 2 chars:

n = "my_string".size
"my_string"[0..n-3] # => "my_stri"

Note: the last string char is at n-1. So, to remove the last 2, we use n-3.

Postgresql: password authentication failed for user "postgres"

i had a similar problem. Ubuntu was left me log in in console with any password for superuser. Except when i connected with -h localhost in psql line command.

I Observed too that "localhost:8080/MyJSPSiteLogIn" - showed: Fatal: autentication error with user "user".

pg_hba.conf was ok.

I noted had two versions of postgres running in the same service.

Solved - uninstalling inutil version.

AngularJS : automatically detect change in model

And if you need to style your form elements according to it's state (modified/not modified) dynamically or to test whether some values has actually changed, you can use the following module, developed by myself:

It adds additional properties and methods to the form and it's child elements. With it, you can test whether some element contains new data or even test if entire form has new unsaved data.

You can setup the following watch: $scope.$watch('myForm.modified', handler) and your handler will be called if some form elements actually contains new data or if it reversed to initial state.

Also, you can use modified property of individual form elements to actually reduce amount of data sent to a server via AJAX call. There is no need to send unchanged data.

As a bonus, you can revert your form to initial state via call to form's reset() method.

You can find the module's demo here:


Can I rollback a transaction I've already committed? (data loss)

No, you can't undo, rollback or reverse a commit.


(Note: if you deleted the data directory off the filesystem, do NOT stop the database. The following advice applies to an accidental commit of a DELETE or similar, not an rm -rf /data/directory scenario).

If this data was important, STOP YOUR DATABASE NOW and do not restart it. Use pg_ctl stop -m immediate so that no checkpoint is run on shutdown.

You cannot roll back a transaction once it has commited. You will need to restore the data from backups, or use point-in-time recovery, which must have been set up before the accident happened.

If you didn't have any PITR / WAL archiving set up and don't have backups, you're in real trouble.

Urgent mitigation

Once your database is stopped, you should make a file system level copy of the whole data directory - the folder that contains base, pg_clog, etc. Copy all of it to a new location. Do not do anything to the copy in the new location, it is your only hope of recovering your data if you do not have backups. Make another copy on some removable storage if you can, and then unplug that storage from the computer. Remember, you need absolutely every part of the data directory, including pg_xlog etc. No part is unimportant.

Exactly how to make the copy depends on which operating system you're running. Where the data dir is depends on which OS you're running and how you installed PostgreSQL.

Ways some data could've survived

If you stop your DB quickly enough you might have a hope of recovering some data from the tables. That's because PostgreSQL uses multi-version concurrency control (MVCC) to manage concurrent access to its storage. Sometimes it will write new versions of the rows you update to the table, leaving the old ones in place but marked as "deleted". After a while autovaccum comes along and marks the rows as free space, so they can be overwritten by a later INSERT or UPDATE. Thus, the old versions of the UPDATEd rows might still be lying around, present but inaccessible.

Additionally, Pg writes in two phases. First data is written to the write-ahead log (WAL). Only once it's been written to the WAL and hit disk, it's then copied to the "heap" (the main tables), possibly overwriting old data that was there. The WAL content is copied to the main heap by the bgwriter and by periodic checkpoints. By default checkpoints happen every 5 minutes. If you manage to stop the database before a checkpoint has happened and stopped it by hard-killing it, pulling the plug on the machine, or using pg_ctl in immediate mode you might've captured the data from before the checkpoint happened, so your old data is more likely to still be in the heap.

Now that you have made a complete file-system-level copy of the data dir you can start your database back up if you really need to; the data will still be gone, but you've done what you can to give yourself some hope of maybe recovering it. Given the choice I'd probably keep the DB shut down just to be safe.


You may now need to hire an expert in PostgreSQL's innards to assist you in a data recovery attempt. Be prepared to pay a professional for their time, possibly quite a bit of time.

I posted about this on the Pg mailing list, and ?????? ?????? linked to depesz's post on pg_dirtyread, which looks like just what you want, though it doesn't recover TOASTed data so it's of limited utility. Give it a try, if you're lucky it might work.

See: pg_dirtyread on GitHub.

I've removed what I'd written in this section as it's obsoleted by that tool.

See also PostgreSQL row storage fundamentals


See my blog entry Preventing PostgreSQL database corruption.

On a semi-related side-note, if you were using two phase commit you could ROLLBACK PREPARED for a transction that was prepared for commit but not fully commited. That's about the closest you get to rolling back an already-committed transaction, and does not apply to your situation.

Testing web application on Mac/Safari when I don't own a Mac

Meanwhile, MacOS High Sierra can be run in VirtualBox (on a PC) for Free. It's not really fast but it works for general browser testing.

How to setup see here:

I'm using this for a while now and it works quite well

JOIN queries vs multiple queries

Here is a link with 100 useful queries, these are tested in Oracle database but remember SQL is a standard, what differ between Oracle, MS SQL Server, MySQL and other databases are the SQL dialect:

Perform an action in every sub-directory using Bash

Handy one-liners

for D in *; do echo "$D"; done
for D in *; do find "$D" -type d; done ### Option A

find * -type d ### Option B

Option A is correct for folders with spaces in between. Also, generally faster since it doesn't print each word in a folder name as a separate entity.

# Option A
$ time for D in ./big_dir/*; do find "$D" -type d > /dev/null; done
real    0m0.327s
user    0m0.084s
sys     0m0.236s

# Option B
$ time for D in `find ./big_dir/* -type d`; do echo "$D" > /dev/null; done
real    0m0.787s
user    0m0.484s
sys     0m0.308s

How can I select all children of an element except the last child?

Nick Craver's solution works but you can also use this:

:nth-last-child(n+2) { /* Your code here */ }

Chris Coyier of CSS Tricks made a nice :nth tester for this.

Speed comparison with Project Euler: C vs Python vs Erlang vs Haskell

Question 3: Can you offer me some hints how to optimize these implementations without changing the way I determine the factors? Optimization in any way: nicer, faster, more "native" to the language.

The C implementation is suboptimal (as hinted at by Thomas M. DuBuisson), the version uses 64-bit integers (i.e. long datatype). I'll investigate the assembly listing later, but with an educated guess, there are some memory accesses going on in the compiled code, which make using 64-bit integers significantly slower. It's that or generated code (be it the fact that you can fit less 64-bit ints in a SSE register or round a double to a 64-bit integer is slower).

Here is the modified code (simply replace long with int and I explicitly inlined factorCount, although I do not think that this is necessary with gcc -O3):

#include <stdio.h>
#include <math.h>

static inline int factorCount(int n)
    double square = sqrt (n);
    int isquare = (int)square;
    int count = isquare == square ? -1 : 0;
    int candidate;
    for (candidate = 1; candidate <= isquare; candidate ++)
        if (0 == n % candidate) count += 2;
    return count;

int main ()
    int triangle = 1;
    int index = 1;
    while (factorCount (triangle) < 1001)
        triangle += index;
    printf ("%d\n", triangle);

Running + timing it gives:

$ gcc -O3 -lm -o euler12 euler12.c; time ./euler12
./euler12  2.95s user 0.00s system 99% cpu 2.956 total

For reference, the haskell implementation by Thomas in the earlier answer gives:

$ ghc -O2 -fllvm -fforce-recomp euler12.hs; time ./euler12                                                                                      [9:40]
[1 of 1] Compiling Main             ( euler12.hs, euler12.o )
Linking euler12 ...
./euler12  9.43s user 0.13s system 99% cpu 9.602 total

Conclusion: Taking nothing away from ghc, its a great compiler, but gcc normally generates faster code.

How to retrieve Jenkins build parameters using the Groovy API?

Regarding parameters:

See this answer first. To get a list of all the builds for a project (obtained as per that answer):


When you find your particular build, you need to get all actions of type ParametersAction with build.getActions(hudson.model.ParametersAction). You then query the returned object for your specific parameters.

Regarding p4.change: I suspect that it is also stored as an action. In Jenkins Groovy console get all actions for a build that contains p4.change and examine them - it will give you an idea what to look for in your code.

Java Round up Any Number

The easiest way to do this is just: You will receive a float or double and want it to convert it to the closest round up then just do System.out.println((int)Math.ceil(yourfloat)); it'll work perfectly

Filezilla FTP Server Fails to Retrieve Directory Listing

Most of the answers here involves configuring, actually just by adding sftp:// on your host (see below image) you can instantly fixed that kind of problem, works for me.

enter image description here

And also take note that if you follow Vaggelis guide you are lowering your security, sftp is better than using plain ftp.

I just changed the encryption from "Use explicit FTP over TLS if available" to "Only use plain FTP" (insecure) at site manager and it works!

Good way to encapsulate Integer.parseInt()

In some cases you should handle parsing errors as fail-fast situations, but in others cases, such as application configuration, I prefer to handle missing input with default values using Apache Commons Lang 3 NumberUtils.

int port = NumberUtils.toInt(properties.getProperty("port"), 8080);

Warning: push.default is unset; its implicit value is changing in Git 2.0

I realize this is an old post but as I just ran into the same issue and had trouble finding the answer I thought I'd add a bit.

So @hammar's answer is correct. Using push.default simple is, in a way, like configuring tracking on your branches so you don't need to specify remotes and branches when pushing and pulling. The matching option will push all branches to their corresponding counterparts on the default remote (which is the first one that was set up unless you've configured your repo otherwise).

One thing I hope others find useful in the future is that I was running Git 1.8 on OS X Mountain Lion and never saw this error. Upgrading to Mavericks is what suddenly made it show up (running git --version will show git version (Apple Git-47) which I'd never seen until the update to the OS.

Convert java.util.Date to java.time.LocalDate

Better way is:

Date date = ...;

Advantages of this version:

  • works regardless the input is an instance of java.util.Date or it's a subclass of java.sql.Date (unlike @JodaStephen's way). This is common with JDBC-originated data. java.sql.Date.toInstant() always throws an exception.

  • it's the same for JDK8 and JDK7 with JSR-310 backport

I personally use an utility class (but it is not backport-compatible):

 * Utilities for conversion between the old and new JDK date types 
 * (between {@code java.util.Date} and {@code java.time.*}).
 * <p>
 * All methods are null-safe.
public class DateConvertUtils {

     * Calls {@link #asLocalDate(Date, ZoneId)} with the system default time zone.
    public static LocalDate asLocalDate(java.util.Date date) {
        return asLocalDate(date, ZoneId.systemDefault());

     * Creates {@link LocalDate} from {@code java.util.Date} or it's subclasses. Null-safe.
    public static LocalDate asLocalDate(java.util.Date date, ZoneId zone) {
        if (date == null)
            return null;

        if (date instanceof java.sql.Date)
            return ((java.sql.Date) date).toLocalDate();
            return Instant.ofEpochMilli(date.getTime()).atZone(zone).toLocalDate();

     * Calls {@link #asLocalDateTime(Date, ZoneId)} with the system default time zone.
    public static LocalDateTime asLocalDateTime(java.util.Date date) {
        return asLocalDateTime(date, ZoneId.systemDefault());

     * Creates {@link LocalDateTime} from {@code java.util.Date} or it's subclasses. Null-safe.
    public static LocalDateTime asLocalDateTime(java.util.Date date, ZoneId zone) {
        if (date == null)
            return null;

        if (date instanceof java.sql.Timestamp)
            return ((java.sql.Timestamp) date).toLocalDateTime();
            return Instant.ofEpochMilli(date.getTime()).atZone(zone).toLocalDateTime();

     * Calls {@link #asUtilDate(Object, ZoneId)} with the system default time zone.
    public static java.util.Date asUtilDate(Object date) {
        return asUtilDate(date, ZoneId.systemDefault());

     * Creates a {@link java.util.Date} from various date objects. Is null-safe. Currently supports:<ul>
     * <li>{@link java.util.Date}
     * <li>{@link java.sql.Date}
     * <li>{@link java.sql.Timestamp}
     * <li>{@link java.time.LocalDate}
     * <li>{@link java.time.LocalDateTime}
     * <li>{@link java.time.ZonedDateTime}
     * <li>{@link java.time.Instant}
     * </ul>
     * @param zone Time zone, used only if the input object is LocalDate or LocalDateTime.
     * @return {@link java.util.Date} (exactly this class, not a subclass, such as java.sql.Date)
    public static java.util.Date asUtilDate(Object date, ZoneId zone) {
        if (date == null)
            return null;

        if (date instanceof java.sql.Date || date instanceof java.sql.Timestamp)
            return new java.util.Date(((java.util.Date) date).getTime());
        if (date instanceof java.util.Date)
            return (java.util.Date) date;
        if (date instanceof LocalDate)
            return java.util.Date.from(((LocalDate) date).atStartOfDay(zone).toInstant());
        if (date instanceof LocalDateTime)
            return java.util.Date.from(((LocalDateTime) date).atZone(zone).toInstant());
        if (date instanceof ZonedDateTime)
            return java.util.Date.from(((ZonedDateTime) date).toInstant());
        if (date instanceof Instant)
            return java.util.Date.from((Instant) date);

        throw new UnsupportedOperationException("Don't know hot to convert " + date.getClass().getName() + " to java.util.Date");

     * Creates an {@link Instant} from {@code java.util.Date} or it's subclasses. Null-safe.
    public static Instant asInstant(Date date) {
        if (date == null)
            return null;
            return Instant.ofEpochMilli(date.getTime());

     * Calls {@link #asZonedDateTime(Date, ZoneId)} with the system default time zone.
    public static ZonedDateTime asZonedDateTime(Date date) {
        return asZonedDateTime(date, ZoneId.systemDefault());

     * Creates {@link ZonedDateTime} from {@code java.util.Date} or it's subclasses. Null-safe.
    public static ZonedDateTime asZonedDateTime(Date date, ZoneId zone) {
        if (date == null)
            return null;
            return asInstant(date).atZone(zone);


The asLocalDate() method here is null-safe, uses toLocalDate(), if input is java.sql.Date (it may be overriden by the JDBC driver to avoid timezone problems or unnecessary calculations), otherwise uses the abovementioned method.

How to Resize image in Swift?

See my blog post, Resize image in swift and objective C, for further details.

Image resize function in swift as below.

func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
    let size = image.size

    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / size.height

    // Figure out what our orientation is, and use that to form the rectangle
    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSizeMake(size.width * heightRatio, size.height * heightRatio)
    } else {
        newSize = CGSizeMake(size.width * widthRatio,  size.height * widthRatio)

    // This is the rect that we've calculated out and this is what is actually used below
    let rect = CGRectMake(0, 0, newSize.width, newSize.height)

    // Actually do the resizing to the rect using the ImageContext stuff
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()

    return newImage

Use the above function and resize image with 200*200 as below code

self.resizeImage(UIImage(named: "yourImageName")!, targetSize: CGSizeMake(200.0, 200.0))

swift3 updated

 func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
    let size = image.size

    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / size.height

    // Figure out what our orientation is, and use that to form the rectangle
    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
    } else {
        newSize = CGSize(width: size.width * widthRatio,  height: size.height * widthRatio)

    // This is the rect that we've calculated out and this is what is actually used below
    let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)

    // Actually do the resizing to the rect using the ImageContext stuff
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.draw(in: rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()

    return newImage!

How to make google spreadsheet refresh itself every 1 minute?

If you are only looking for a refresh rate for the GOOGLEFINANCE function, keep in mind that data delays can be up to 20 minutes (per Google Finance Disclaimer).

Single-symbol refresh rate (using GoogleClock)

Here is a modified version of the refresh action, taking the data delay into consideration, to save on unproductive refresh cycles.


For example, with:

  • DATA DELAY: 15 (minutes)



Results in a dynamic data-based refresh rate of:


Multi-symbol refresh rate (using GoogleClock)

If your sheet contains a number of rows of symbols, you could add a datadelay column for each symbol and use the lowest value, for example:


Where dataDelayValuesNamedRange is the absolute reference or named reference of the range of cells that contain the data delay values for each symbol (assuming these values are different).

Without GoogleClock()

The GoogleClock() function was removed in 2014 and replaced with settings setup for refreshing sheets. At present, I have confirmed that replacement settings is only on available in Sheets from when accessed from a desktop browser, not the mobile app (I'm using Google's mobile Sheets app updated 2016-03-14).

(This part of the answer is based on, and portions copied from, Google Docs Help)

To change how often "some" Google Sheets functions update:

  1. Open a spreadsheet. Click File > Spreadsheet settings.
  2. In the RECALCULATION section, choose a setting from the drop-down menu.
  3. Setting options are:
    • On change
    • On change and every minute
    • On change and every hour

NOTE External data functions recalculate at the following intervals:

  • ImportRange: 30 minutes
  • ImportHtml, ImportFeed, ImportData, ImportXml: 1 hour
  • GoogleFinance: 2 minutes

The references in earlier sections to the display and use of the datadelay attribute still apply, as well as the concepts for more efficient coding of sheets.

On a positive note, the new refresh option continues to be refreshed by Google servers regardless of whether you have the sheet loaded or not. That's a positive for shared sheets for sure; even more so for Google Apps Scripts (GAS), where GAS is used in workflow code or referenced data is used as a trigger for an event.

[*] in my understanding so far (I am currently testing this)

Problems after upgrading to Xcode 10: Build input file cannot be found

This worked for me in Xcode 10:

  • Click Project icon/name in your Xcode project
  • Go to General tab
  • Click [Choose info.plist File] under Identity section
  • Select the info.Plist file
  • Check Info tab to see if info.plist was loaded successfully
  • Build and run

Difference between -XX:+UseParallelGC and -XX:+UseParNewGC

Parallel GC

  • XX:+UseParallelGC Use parallel garbage collection for scavenges. (Introduced in 1.4.1)
  • XX:+UseParallelOldGC Use parallel garbage collection for the full collections. Enabling this option automatically sets -XX:+UseParallelGC. (Introduced in 5.0 update 6.)


UseParNewGC A parallel version of the young generation copying collector is used with the concurrent collector (i.e. if -XX:+ UseConcMarkSweepGC is used on the command line then the flag UseParNewGC is also set to true if it is not otherwise explicitly set on the command line).

Perhaps the easiest way to understand was combinations of garbage collection algorithms made by Alexey Ragozin

<table border="1" style="width:100%">_x000D_
    <td align="center">Young collector</td>_x000D_
    <td align="center">Old collector</td>_x000D_
    <td align="center">JVM option</td>_x000D_
    <td>Serial (DefNew)</td>_x000D_
    <td>Serial Mark-Sweep-Compact</td>_x000D_
    <td>Parallel scavenge (PSYoungGen)</td>_x000D_
    <td>Serial Mark-Sweep-Compact (PSOldGen)</td>_x000D_
    <td>Parallel scavenge (PSYoungGen)</td>_x000D_
    <td>Parallel Mark-Sweep-Compact (ParOldGen)</td>_x000D_
    <td>Serial (DefNew)</td>_x000D_
    <td>Concurrent Mark Sweep</td>_x000D_
    <td>Parallel (ParNew)</td>_x000D_
    <td>Concurrent Mark Sweep</td>_x000D_
    <td colspan="2">G1</td>_x000D_


  1. Apply -XX:+UseParallelGC when you require parallel collection method over YOUNG generation ONLY, (but still) use serial-mark-sweep method as OLD generation collection
  2. Apply -XX:+UseParallelOldGC when you require parallel collection method over YOUNG generation (automatically sets -XX:+UseParallelGC) AND OLD generation collection
  3. Apply -XX:+UseParNewGC & -XX:+UseConcMarkSweepGC when you require parallel collection method over YOUNG generation AND require CMS method as your collection over OLD generation memory
  4. You can't apply -XX:+UseParallelGC or -XX:+UseParallelOldGC with -XX:+UseConcMarkSweepGC simultaneously, that's why your require -XX:+UseParNewGC to be paired with CMS otherwise use -XX:+UseSerialGC explicitly OR -XX:-UseParNewGC if you wish to use serial method against young generation

Install tkinter for Python

If you are using Python 3 it might be because you are typing Tkinter not tkinter

How can I determine whether a 2D Point is within a Polygon?

Here is a C# version of the answer given by nirg, which comes from this RPI professor. Note that use of the code from that RPI source requires attribution.

A bounding box check has been added at the top. However, as James Brown points out, the main code is almost as fast as the bounding box check itself, so the bounding box check can actually slow the overall operation, in the case that most of the points you are checking are inside the bounding box. So you could leave the bounding box check out, or an alternative would be to precompute the bounding boxes of your polygons if they don't change shape too often.

public bool IsPointInPolygon( Point p, Point[] polygon )
    double minX = polygon[ 0 ].X;
    double maxX = polygon[ 0 ].X;
    double minY = polygon[ 0 ].Y;
    double maxY = polygon[ 0 ].Y;
    for ( int i = 1 ; i < polygon.Length ; i++ )
        Point q = polygon[ i ];
        minX = Math.Min( q.X, minX );
        maxX = Math.Max( q.X, maxX );
        minY = Math.Min( q.Y, minY );
        maxY = Math.Max( q.Y, maxY );

    if ( p.X < minX || p.X > maxX || p.Y < minY || p.Y > maxY )
        return false;

    bool inside = false;
    for ( int i = 0, j = polygon.Length - 1 ; i < polygon.Length ; j = i++ )
        if ( ( polygon[ i ].Y > p.Y ) != ( polygon[ j ].Y > p.Y ) &&
             p.X < ( polygon[ j ].X - polygon[ i ].X ) * ( p.Y - polygon[ i ].Y ) / ( polygon[ j ].Y - polygon[ i ].Y ) + polygon[ i ].X )
            inside = !inside;

    return inside;

What is the difference between char * const and const char *?

// Some more complex constant variable/pointer declaration.
// Observing cases when we get error and warning would help
// understanding it better.

int main(void)
  char ca1[10]= "aaaa"; // char array 1
  char ca2[10]= "bbbb"; // char array 2

  char *pca1= ca1;
  char *pca2= ca2;

  char const *ccs= pca1;
  char * const csc= pca2;
  ccs[1]='m';  // Bad - error: assignment of read-only location ‘*(ccs + 1u)’
  ccs= csc;    // Good

  csc[1]='n';  // Good
  csc= ccs;    // Bad - error: assignment of read-only variable ‘csc’

  char const **ccss= &ccs;     // Good
  char const **ccss1= &csc;    // Bad - warning: initialization from incompatible pointer type

  char * const *cscs= &csc;    // Good
  char * const *cscs1= &ccs;   // Bad - warning: initialization from incompatible pointer type

  char ** const cssc=   &pca1; // Good
  char ** const cssc1=  &ccs;  // Bad - warning: initialization from incompatible pointer type
  char ** const cssc2=  &csc;  // Bad - warning: initialization discards ‘const’
                               //                qualifier from pointer target type

  *ccss[1]= 'x'; // Bad - error: assignment of read-only location ‘**(ccss + 8u)’
  *ccss= ccs;    // Good
  *ccss= csc;    // Good
  ccss= ccss1;   // Good
  ccss= cscs;    // Bad - warning: assignment from incompatible pointer type

  *cscs[1]= 'y'; // Good
  *cscs= ccs;    // Bad - error: assignment of read-only location ‘*cscs’
  *cscs= csc;    // Bad - error: assignment of read-only location ‘*cscs’
  cscs= cscs1;   // Good
  cscs= cssc;    // Good

  *cssc[1]= 'z'; // Good
  *cssc= ccs;    // Bad - warning: assignment discards ‘const’
                 //                qualifier from pointer target type
  *cssc= csc;    // Good
  *cssc= pca2;   // Good
  cssc= ccss;    // Bad - error: assignment of read-only variable ‘cssc’
  cssc= cscs;    // Bad - error: assignment of read-only variable ‘cssc’
  cssc= cssc1;   // Bad - error: assignment of read-only variable ‘cssc’

Multiple conditions in ngClass - Angular 4

<a [ngClass]="{'class1':array.status === 'active','class2':array.status === 'idle','class3':array.status === 'inactive',}">

How is an HTTP POST request made in node.js?

Axios is a promise based HTTP client for the browser and Node.js. Axios makes it easy to send asynchronous HTTP requests to REST endpoints and perform CRUD operations. It can be used in plain JavaScript or with a library such as Vue or React.

const axios = require('axios');

        var dataToPost = {
          email: "your email",
          password: "your password"

        let axiosConfiguration = {
          headers: {
              'Content-Type': 'application/json;charset=UTF-8',
              "Access-Control-Allow-Origin": "*",
        };'endpoint or url', dataToPost, axiosConfiguration)
        .then((res) => {
          console.log("Response: ", res);
        .catch((err) => {
          console.log("error: ", err);

Change bar plot colour in geom_bar with ggplot2 in r

If you want all the bars to get the same color (fill), you can easily add it inside geom_bar.

ggplot(data=df, aes(x=c1+c2/2, y=c3)) + 
geom_bar(stat="identity", width=c2, fill = "#FF6666")

enter image description here

Add fill = the_name_of_your_var inside aes to change the colors depending of the variable :

c4 = c("A", "B", "C")
df = cbind(df, c4)
ggplot(data=df, aes(x=c1+c2/2, y=c3, fill = c4)) + 
geom_bar(stat="identity", width=c2)

enter image description here

Use scale_fill_manual() if you want to manually the change of colors.

ggplot(data=df, aes(x=c1+c2/2, y=c3, fill = c4)) + 
geom_bar(stat="identity", width=c2) + 
scale_fill_manual("legend", values = c("A" = "black", "B" = "orange", "C" = "blue"))

enter image description here

Drop shadow for PNG image in CSS

This won't be possible with css - an image is a square, and so the shadow would be the shadow of a square. The easiest way would be to use photoshop/gimp or any other image editor to apply the shadow like core draw.

How do you close/hide the Android soft keyboard using Java?

Here are both hide & show methods.


fun hideKeyboard(activity: Activity) {
    val v = activity.currentFocus
    val imm = activity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    assert(v != null)
    imm.hideSoftInputFromWindow(v!!.windowToken, InputMethodManager.HIDE_NOT_ALWAYS)

private fun showKeyboard(activity: Activity) {
    val v = activity.currentFocus
    val imm = activity.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    assert(v != null)
    imm.showSoftInput(v, InputMethodManager.SHOW_IMPLICIT)


public static void hideKeyboard(Activity activity) {
    View v = activity.getCurrentFocus();
    InputMethodManager imm = (InputMethodManager) activity.getSystemService(Context.INPUT_METHOD_SERVICE);
    assert imm != null && v != null;
    imm.hideSoftInputFromWindow(v.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);

private static void showKeyboard(Activity activity) {
    View v = activity.getCurrentFocus();
    InputMethodManager imm = (InputMethodManager) activity.getSystemService(Context.INPUT_METHOD_SERVICE);
    assert imm != null && v != null;
    imm.showSoftInput(v, InputMethodManager.SHOW_IMPLICIT);

undefined reference to boost::system::system_category() when compiling

When using CMAKE and find_package, make sure it is :

find_package(Boost COMPONENTS system ...)

and not

find_package(boost COMPONENTS system ...)

Some people may have lost hours for that ...

Hide text within HTML?

Not sure if this was what you were asking for, but I was personally trying to 'hide' some info in my html so that if someone inspected it, they would see the text in the source code.

It turns out that you can add ANY attribute, and so long as it isn't understood by the browser, it will just be left buried in the tag. My code was an easter egg: For people who couldn't afford to do the Makers Academy course, I basically encouraged them to inspect the element, where they would be given a secret URL where they could apply for a special, cut-price course (it's in haml, but it's the same idea in HTML):

        %h2 I can't afford to do the course... What should I do?
        %p{:url_you_should_visit => ''} Inspect and you shall find.

Or in html:

<p url_you_should_visit="">Inspect and you shall find.</p>

Because 'url' is not a recognised html attribute, it makes no difference but is still discoverable. You could do the same with anything you wanted. You could have an attribute (in html) like:

<p thanks="Thanks to all the bloggers that helped me"> Some text </p>

And they'll be able to find your little easter egg if they want it... Hope that helps - it certainly helped me :)

How to match a substring in a string, ignoring case

you can also use: s.lower() in str.lower()

How to use sed to replace only the first occurrence in a file?

sed '0,/pattern/s/pattern/replacement/' filename

this worked for me.


sed '0,/<Menu>/s/<Menu>/<Menu><Menu>Sub menu<\/Menu>/' try.txt > abc.txt

Editor's note: both work with GNU sed only.

Save the plots into a PDF

import datetime
import numpy as np
from matplotlib.backends.backend_pdf import PdfPages
import matplotlib.pyplot as plt

# Create the PdfPages object to which we will save the pages:
# The with statement makes sure that the PdfPages object is closed properly at
# the end of the block, even if an Exception occurs.
with PdfPages('multipage_pdf.pdf') as pdf:
    plt.figure(figsize=(3, 3))
    plt.plot(range(7), [3, 1, 4, 1, 5, 9, 2], 'r-o')
    plt.title('Page One')
    pdf.savefig()  # saves the current figure into a pdf page

    plt.rc('text', usetex=True)
    plt.figure(figsize=(8, 6))
    x = np.arange(0, 5, 0.1)
    plt.plot(x, np.sin(x), 'b-')
    plt.title('Page Two')

    plt.rc('text', usetex=False)
    fig = plt.figure(figsize=(4, 5))
    plt.plot(x, x*x, 'ko')
    plt.title('Page Three')
    pdf.savefig(fig)  # or you can pass a Figure object to pdf.savefig

    # We can also set the file's metadata via the PdfPages object:
    d = pdf.infodict()
    d['Title'] = 'Multipage PDF Example'
    d['Author'] = u'Jouni K. Sepp\xe4nen'
    d['Subject'] = 'How to create a multipage pdf file and set its metadata'
    d['Keywords'] = 'PdfPages multipage keywords author title subject'
    d['CreationDate'] = datetime.datetime(2009, 11, 13)
    d['ModDate'] =

How does the data-toggle attribute work? (What's its API?)

The data-* attributes is used to store custom data private to the page or application

So Bootstrap uses these attributes for saving states of objects

W3School data-* description

How to select a radio button by default?

They pretty much got it there... just like a checkbox, all you have to do is add the attribute checked="checked" like so:

<input type="radio" checked="checked">

...and you got it.


ASP.NET MVC: What is the purpose of @section?

You want to use sections when you want a bit of code/content to render in a placeholder that has been defined in a layout page.

In the specific example you linked, he has defined the RenderSection in the _Layout.cshtml. Any view that uses that layout can define an @section of the same name as defined in Layout, and it will replace the RenderSection call in the layout.

Perhaps you're wondering how we know Index.cshtml uses that layout? This is due to a bit of MVC/Razor convention. If you look at the dialog where he is adding the view, the box "Use layout or master page" is checked, and just below that it says "Leave empty if it is set in a Razor _viewstart file". It isn't shown, but inside that _ViewStart.cshtml file is code like:

    Layout = "~/Views/Shared/_Layout.cshtml";

The way viewstarts work is that any cshtml file within the same directory or child directories will run the ViewStart before it runs itself.

Which is what tells us that Index.cshtml uses Shared/_Layout.cshtml.

SQL Server: Cannot insert an explicit value into a timestamp column

There is some good information in these answers. Suppose you are dealing with databases which you can't alter, and that you are copying data from one version of the table to another, or from the same table in one database to another. Suppose also that there are lots of columns, and you either need data from all the columns, or the columns which you don't need don't have default values. You need to write a query with all the column names.

Here is a query which returns all the non-timestamp column names for a table, which you can cut and paste into your insert query. FYI: 189 is the type ID for timestamp.

declare @TableName nvarchar(50) = 'Product';

select stuff(
        ', ' +
        (select id from sysobjects where xtype = 'U' and name = @TableName) tables
        inner join syscolumns columns on =
    where columns.xtype <> 189
    for xml path('')), 1, 2, '')

Just change the name of the table at the top from 'Product' to your table name. The query will return a list of column names:

ProductID, Name, ProductNumber, MakeFlag, FinishedGoodsFlag, Color, SafetyStockLevel, ReorderPoint, StandardCost, ListPrice, Size, SizeUnitMeasureCode, WeightUnitMeasureCode, Weight, DaysToManufacture, ProductLine, Class, Style, ProductSubcategoryID, ProductModelID, SellStartDate, SellEndDate, DiscontinuedDate, rowguid, ModifiedDate

If you are copying data from one database (DB1) to another database(DB2) you could use this query.

insert DB2.dbo.Product (ProductID, Name, ProductNumber, MakeFlag, FinishedGoodsFlag, Color, SafetyStockLevel, ReorderPoint, StandardCost, ListPrice, Size, SizeUnitMeasureCode, WeightUnitMeasureCode, Weight, DaysToManufacture, ProductLine, Class, Style, ProductSubcategoryID, ProductModelID, SellStartDate, SellEndDate, DiscontinuedDate, rowguid, ModifiedDate)
select ProductID, Name, ProductNumber, MakeFlag, FinishedGoodsFlag, Color, SafetyStockLevel, ReorderPoint, StandardCost, ListPrice, Size, SizeUnitMeasureCode, WeightUnitMeasureCode, Weight, DaysToManufacture, ProductLine, Class, Style, ProductSubcategoryID, ProductModelID, SellStartDate, SellEndDate, DiscontinuedDate, rowguid, ModifiedDate 
from DB1.dbo.Product

Event on a disabled input

Disabled elements don't fire mouse events. Most browsers will propagate an event originating from the disabled element up the DOM tree, so event handlers could be placed on container elements. However, Firefox doesn't exhibit this behaviour, it just does nothing at all when you click on a disabled element.

I can't think of a better solution but, for complete cross browser compatibility, you could place an element in front of the disabled input and catch the click on that element. Here's an example of what I mean:

<div style="display:inline-block; position:relative;">
  <input type="text" disabled />
  <div style="position:absolute; left:0; right:0; top:0; bottom:0;"></div>


$("div > div").click(function (evt) {
    $(this).hide().prev("input[disabled]").prop("disabled", false).focus();

Example: (updated to use jQuery 1.7 with prop instead of attr).

jQuery jump or scroll to certain position, div or target on the page from button onclick

$("html, body").scrollTop($(element).offset().top); // <-- Also integer can be used

ORA-01843 not a valid month- Comparing Dates

I know this is a bit late, but I'm having a similar issue. SQL*Plus executes the query successfully, but Oracle SQL Developer shows the ORA-01843: not a valid month error.

SQL*Plus seems to know that the date I'm using is in the valid format, whereas Oracle SQL Developer needs to be told explicitly what format my date is in.

  • SQL*Plus statement:

    select count(*) from some_table where DATE_TIME_CREATED < '09-12-23';


  • Oracle SQL Developer statement:

     select count(*) from some_table where DATE_TIME_CREATED < TO_DATE('09-12-23','RR-MM-DD');

How can I submit form on button click when using preventDefault()?

Ok, first e.preventDefault(); it's not a Jquery element, it's a method of javascript, now what it's true it's if you add this method you avoid the submit the event, now what you could do it's send the form by ajax something like this

     url: $(this).attr('action'),
     data : $(this).serialize(),
     success : function (data){


how to destroy an object in java?

Set to null. Then there are no references anymore and the object will become eligible for Garbage Collection. GC will automatically remove the object from the heap.

Unable to allocate array with shape and data type

I came across this problem on Windows too. The solution for me was to switch from a 32-bit to a 64-bit version of Python. Indeed, a 32-bit software, like a 32-bit CPU, can adress a maximum of 4 GB of RAM (2^32). So if you have more than 4 GB of RAM, a 32-bit version cannot take advantage of it.

With a 64-bit version of Python (the one labeled x86-64 in the download page), the issue disappeared.

You can check which version you have by entering the interpreter. I, with a 64-bit version, now have: Python 3.7.5rc1 (tags/v3.7.5rc1:4082f600a5, Oct 1 2019, 20:28:14) [MSC v.1916 64 bit (AMD64)], where [MSC v.1916 64 bit (AMD64)] means "64-bit Python".

Note : as of the time of this writing (May 2020), matplotlib is not available on python39, so I recommand installing python37, 64 bits.

Sources :

How to Auto-start an Android Application?

If by autostart you mean auto start on phone bootup then you should register a BroadcastReceiver for the BOOT_COMPLETED Intent. Android systems broadcasts that intent once boot is completed.

Once you receive that intent you can launch a Service that can do whatever you want to do.

Keep note though that having a Service running all the time on the phone is generally a bad idea as it eats up system resources even when it is idle. You should launch your Service / application only when needed and then stop it when not required.

How To Execute SSH Commands Via PHP

For those using the Symfony framework, the phpseclib can also be used to connect via SSH. It can be installed using composer:

composer require phpseclib/phpseclib

Next, simply use it as follows:

use phpseclib\Net\SSH2;

// Within a controller for example:
$ssh = new SSH2('hostname or ip');
if (!$ssh->login('username', 'password')) {
    // Login failed, do something

$return_value = $ssh->exec('command');

Retrieving the last record in each group - MySQL

The below query will work fine as per your question.

 SELECT SUBSTR(Others_data,1,2),MAX(Others_data) AS Max_Others_data
) M2
WHERE M1.Others_data = M2.Max_Others_data
ORDER BY Others_data;

How to make html <select> element look like "disabled", but pass values?

<select id="test" name="sel">
  <option disabled>1</option>
  <option disabled>2</option>

or you can use jQuery

$("#test option:not(:selected)").prop("disabled", true);

What is the meaning of "POSIX"?

POSIX defines set of standards for an operating system or a program. The goal is to write new software that is compatible with UNIX-like systems.

For example a program runs on Linux is also can be compile and run on other UNIX-like systems like Solaris, HP-UX, and AIX etc..

The most popular examples are GNU Bash which is 100% POSIX compliance and gawk utility.

Stored procedure or function expects parameter which is not supplied

In my case I received this exception even when all parameter values were correctly supplied but the type of command was not specified :

cmd.CommandType = System.Data.CommandType.StoredProcedure;

This is obviously not the case in the question above, but exception description is not very clear in this case, so I decided to specify that.

How to convert all tables in database to one collation?

This is my version of a bash script. It takes database name as a parameter and converts all tables to another charset and collation (given by another parameters or default value defined in the script).


# <database> [<charset> <collation>]
# changes MySQL/MariaDB charset and collation for one database - all tables and
# all columns in all tables


[ -n "$DB" ] || exit 1
[ -n "$CHARSET" ] || CHARSET="utf8mb4"
[ -n "$COLL" ] || COLL="utf8mb4_general_ci"

echo $DB

echo "USE $DB; SHOW TABLES;" | mysql -s | (
    while read TABLE; do
        echo $DB.$TABLE

Viewing root access files/folders of android on windows

Obviously, you'll need a rooted android device. Then set up an FTP server and transfer the files.

how to transfer a file through SFTP in java?

Try this code.

public void send (String fileName) {
    String SFTPHOST = "host:IP";
    int SFTPPORT = 22;
    String SFTPUSER = "username";
    String SFTPPASS = "password";
    String SFTPWORKINGDIR = "file/to/transfer";

    Session session = null;
    Channel channel = null;
    ChannelSftp channelSftp = null;
    System.out.println("preparing the host information for sftp.");

    try {
        JSch jsch = new JSch();
        session = jsch.getSession(SFTPUSER, SFTPHOST, SFTPPORT);
        java.util.Properties config = new java.util.Properties();
        config.put("StrictHostKeyChecking", "no");
        System.out.println("Host connected.");
        channel = session.openChannel("sftp");
        System.out.println("sftp channel opened and connected.");
        channelSftp = (ChannelSftp) channel;;
        File f = new File(fileName);
        channelSftp.put(new FileInputStream(f), f.getName());"File transfered successfully to host.");
    } catch (Exception ex) {
        System.out.println("Exception found while tranfer the response.");
    } finally {
        System.out.println("sftp Channel exited.");
        System.out.println("Channel disconnected.");
        System.out.println("Host Session disconnected.");

maven command line how to point to a specific settings.xml for a single command?

You can simply use:

mvn --settings YourOwnSettings.xml clean install


mvn -s YourOwnSettings.xml clean install

HTML 5: Is it <br>, <br/>, or <br />?

Ummm.....does anyone know a SINGLE vendor, user-agent, or browser maker that has ever followed the W3C Specifications 100%??? So if HTML5 says it supports all three break element versions, you can bet the vendors support the same and even more sloppier versions!

The ONLY thing that matters in this debate is to CONSISTENTLY use coding that also happens to follow XML specifications as well as HTML specifications when possible. That means you should use the correct XML version of the break tag and encourage all your team to do the same:

<br />

The same space-slash format should apply for the img, a, hr, and meta tags in your code. Why? Because:

  1. Its is backwards compatible with older XHTML user-agents / browsers
  2. The browser vendors support the XML version anyway so the HTML5 specification is moot.
  3. The sloppy implementations of most user-agents today, in the past, and in the future will accept it.
  4. It allows your markup to be comparable with XML standards should you need to go back to creating XHTML/XML documents from your markup.
  5. It's "good coding practice" for ALL WEB DEVELOPERS to keep using solid markup practices that follow XML, including coding in all lower case, quoted attributes, escaped XML characters, etc. etc. Why? In the future if you have to switch to XML data you automatically code and think in XML.
  6. We can only hope that in the future World Wide Web, we move away from private vendor-implemented standards and go back to solid, reliable, verified markup that parses faster, moves data over the wires faster, and make our future Internet a more standardized medium using XML.

Besides, in the robotic and machine world that's here, where robots don't have the same Human-interface coding problems HTML5 solves for us, they will gladly go back to XML data systems and parse such UI web pages much faster when converted to XML data.

How to get column values in one comma separated value

I think it will be easy to you. I am using group_concat which concatenate diffent values with separator as we have defined

select ID,User, GROUP_CONCAT(Distinct Department order  by Department asc 

separator ', ') as Department from Table_Name   group by ID

How to check for an undefined or null variable in JavaScript?

You have to differentiate between cases:

  1. Variables can be undefined or undeclared. You'll get an error if you access an undeclared variable in any context other than typeof.
if(typeof someUndeclaredVar == whatever) // works
if(someUndeclaredVar) // throws error

A variable that has been declared but not initialized is undefined.

let foo;
if (foo) //evaluates to false because foo === undefined
  1. Undefined properties , like someExistingObj.someUndefProperty. An undefined property doesn't yield an error and simply returns undefined, which, when converted to a boolean, evaluates to false. So, if you don't care about 0 and false, using if(obj.undefProp) is ok. There's a common idiom based on this fact:

    value = obj.prop || defaultValue

    which means "if obj has the property prop, assign it to value, otherwise assign the default value defautValue".

    Some people consider this behavior confusing, arguing that it leads to hard-to-find errors and recommend using the in operator instead

    value = ('prop' in obj) ? obj.prop : defaultValue

Dynamic SELECT TOP @var In SQL Server

In x0n's example, it should be:


SELECT * from sometable


Javascript: How to loop through ALL DOM elements on a page?

Getting all elements using var all = document.getElementsByTagName("*"); for (var i=0, max=all.length; i < max; i++); is ok if you need to check every element but will result in checking or looping repeating elements or text.

Below is a recursion implementation that checks or loop each element of all DOM elements only once and append:

(Credits to @George Reith for his recursion answer here: Map HTML to JSON)

function mapDOMCheck(html_string, json) {
  treeObject = {}

  dom = new jsdom.JSDOM(html_string) // use jsdom because DOMParser does not provide client-side Window for element access
  document = dom.window.document
  element = document.querySelector('html')

  // Recurse and loop through DOM elements only once
  function treeHTML(element, object) {
    var nodeList = element.childNodes;

    if (nodeList != null) {
      if (nodeList.length) {
        object[element.nodeName] = []; // IMPT: empty [] array for parent node to push non-text recursivable elements (see below)

        for (var i = 0; i < nodeList.length; i++) {
          console.log("nodeName", nodeList[i].nodeName);

          if (nodeList[i].nodeType == 3) { // if child node is **final base-case** text node
            console.log("nodeValue", nodeList[i].nodeValue);
          } else { // else
            object[element.nodeName].push({}); // push {} into empty [] array where {} for recursivable elements
            treeHTML(nodeList[i], object[element.nodeName][object[element.nodeName].length - 1]);

  treeHTML(element, treeObject);


How do I create a local database inside of Microsoft SQL Server 2014?

As per comments, First you need to install an instance of SQL Server if you don't already have one -

Once this is installed you must connect to this instance (server) and then you can create a database here -

Auto detect mobile browser (via user-agent?)

Just a thought but what if you worked this problem from the opposite direction? Rather than determining which browsers are mobile why not determine which browsers are not? Then code your site to default to the mobile version and redirect to the standard version. There are two basic possibilities when looking at a mobile browser. Either it has javascript support or it doesn't. So if the browser does not have javascript support it will default to the mobile version. If it does have JavaScript support, check the screen size. Anything below a certain size will likely also be a mobile browser. Anything larger will get redirected to your standard layout. Then all you need to do is determine if the user with JavaScript disabled is mobile or not.
According to the W3C the number of users with JavaScript disabled was about 5% and of those users most have turned it off which implies that they actually know what they are doing with a browser. Are they a large part of your audience? If not then don't worry about them. If so, whats the worst case scenario? You have those users browsing the mobile version of your site, and that's a good thing.

Disable form auto submit on button click

if you want to add directly to input as attribute, use this

 onclick="return false;" 

<input id = "btnPlay" type="button" onclick="return false;" value="play" /> 

this will prevent form submit behaviour

Eclipse Java error: This selection cannot be launched and there are no recent launches

click on the project that you want to run on the left side in package explorer and then click the Run button.

How to print a query string with parameter values when using Hibernate

You can log this:


Output example:

2013-10-31 14:56:19,029 DEBUG [net.sf.hibernate.hql.QueryTranslator] HQL: select, noti.idmicrosite, noti.fcaducidad, noti.fpublicacion, noti.tipo, noti.imagen, noti.visible, trad.titulo, trad.subtitulo, trad.laurl, trad.urlnom, trad.fuente, trad.texto  from org.ibit.rol.sac.micromodel.Noticia noti join noti.traducciones trad where index(trad)='ca' and noti.visible='S' and noti.idmicrosite=985 and noti.tipo=3446

2013-10-31 14:56:19,029 DEBUG [net.sf.hibernate.hql.QueryTranslator] SQL: select noticia0_.NOT_CODI as x0_0_, noticia0_.NOT_MICCOD as x1_0_, noticia0_.NOT_CADUCA as x2_0_, noticia0_.NOT_PUBLIC as x3_0_, noticia0_.NOT_TIPO as x4_0_, noticia0_.NOT_IMAGEN as x5_0_, noticia0_.NOT_VISIB as x6_0_, traduccion1_.NID_TITULO as x7_0_, traduccion1_.NID_SUBTIT as x8_0_, traduccion1_.NID_URL as x9_0_, traduccion1_.NID_URLNOM as x10_0_, traduccion1_.NID_FUENTE as x11_0_, traduccion1_.NID_TEXTO as x12_0_ from GUS_NOTICS noticia0_ inner join GUS_NOTIDI traduccion1_ on noticia0_.NOT_CODI=traduccion1_.NID_NOTCOD where (traduccion1_.NID_CODIDI='ca' )and(noticia0_.NOT_VISIB='S' )and(noticia0_.NOT_MICCOD=985 )and(noticia0_.NOT_TIPO=3446 )

Difference between a User and a Login in SQL Server

I think this is a very useful question with good answer. Just to add my two cents from the MSDN Create a Login page:

A login is a security principal, or an entity that can be authenticated by a secure system. Users need a login to connect to SQL Server. You can create a login based on a Windows principal (such as a domain user or a Windows domain group) or you can create a login that is not based on a Windows principal (such as an SQL Server login).

To use SQL Server Authentication, the Database Engine must use mixed mode authentication. For more information, see Choose an Authentication Mode.

As a security principal, permissions can be granted to logins. The scope of a login is the whole Database Engine. To connect to a specific database on the instance of SQL Server, a login must be mapped to a database user. Permissions inside the database are granted and denied to the database user, not the login. Permissions that have the scope of the whole instance of SQL Server (for example, the CREATE ENDPOINT permission) can be granted to a login.

Eloquent get only one column as an array

You can use the pluck method:

Word_relation::where('word_one', $word_id)->pluck('word_two')->toArray();

For more info on what methods are available for using with collection, you can you can check out the Laravel Documentation.

How to print a list with integers without the brackets, commas and no quotes?

Using .format from Python 2.6 and higher:

>>> print '{}{}{}{}'.format(*[7,7,7,7])
>>> data = [7, 7, 7, 7] * 3
>>> print ('{}'*len(data)).format(*data)

For Python 3:

>>> print(('{}'*len(data)).format(*data))

How to change the foreign key referential action? (behavior)

You can do this in one query if you're willing to change its name:

ALTER TABLE table_name
  DROP FOREIGN KEY `fk_name`,
  ADD CONSTRAINT `fk_name2` FOREIGN KEY (`remote_id`)
    REFERENCES `other_table` (`id`)

This is useful to minimize downtime if you have a large table.

Multiplication on command line terminal

The classical solution is:

 expr 5 \* 5

expr will only work with integer operands. Another nice option is:

 echo 5 5\*p | dc

dc can be made to work with non-integer operands.

How do I check if an array includes a value in JavaScript?

Adding a unique item to a another list

searchResults: [
                    name: 'Hello',
                    artist: 'Selana',
                    album: 'Riga',
                    id: 1,
                    name: 'Hello;s',
                    artist: 'Selana G',
                    album: 'Riga1',
                    id: 2,
                    name: 'Hello2',
                    artist: 'Selana',
                    album: 'Riga11',
                    id: 3,
            playlistTracks: [
                name: 'Hello',
                artist: 'Mamunuus',
                album: 'Riga',
                id: 4,
                name: 'Hello;s',
                artist: 'Mamunuus G',
                album: 'Riga1',
                id: 2,
                name: 'Hello2',
                artist: 'Mamunuus New',
                album: 'Riga11',
                id: 3,
            playlistName: "New PlayListTrack",

    // Adding an unique track in the playList
    addTrack = track => {
      if(playlistTracks.find(savedTrack => === {


Using HTML5/JavaScript to generate and save a file

You can use localStorage. This is the Html5 equivalent of cookies. It appears to work on Chrome and Firefox BUT on Firefox, I needed to upload it to a server. That is, testing directly on my home computer didn't work.

I'm working up HTML5 examples. Go to and scroll to the maze one. The information to re-build the maze is stored using localStorage.

I came to this article looking for HTML5 JavaScript for loading and working with xml files. Is it the same as older html and JavaScript????

C# LINQ find duplicates in List

To find the duplicate values only :

var duplicates = list.GroupBy(x => x.Key).Any(g => g.Count() > 1);


var list = new[] {1,2,3,1,4,2};

GroupBy will group the numbers by their keys and will maintain the count (number of times it repeated) with it. After that, we are just checking the values who have repeated more than once.

To find the unique values only :

var unique = list.GroupBy(x => x.Key).All(g => g.Count() == 1);


var list = new[] {1,2,3,1,4,2};

GroupBy will group the numbers by their keys and will maintain the count (number of times it repeated) with it. After that, we are just checking the values who have repeated only once means are unique.

What is the difference between procedural programming and functional programming?


In Haskell there is a library function called product:

prouduct list = foldr 1 (*) list

or simply:

product = foldr 1 (*)

so the "idiomatic" factorial

fac n = foldr 1 (*)  [1..n]

would simply be

fac n = product [1..n]

How to insert close button in popover for Bootstrap

I have struggle with this one and this is the simplest way to do it, 3 lines of js:

  1. Add a cross in the title of the popover
  2. use the js snippet to show the popover and to close by clicking the header
  3. Use a bit of css to make it nice

enter image description here

$(document).ready(function() {_x000D_
  // This is to overwrite the boostrap default and show it allways_x000D_
  // This is to destroy the popover when you click the title_x000D_
@import "";_x000D_
/* Just to align my example */_x000D_
.btn {_x000D_
  margin: 90px auto;_x000D_
  margin-left: 90px;_x000D_
/* Styles for header */_x000D_
.popover-title {_x000D_
  border: 0;_x000D_
  background: transparent;_x000D_
  cursor: pointer;_x000D_
  display: inline-block;_x000D_
  float: right;_x000D_
  text-align: right; _x000D_
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<button id="myPopUp" class="btn btn-success" data-toggle="popover" data-placement="top" data-title="×" data-content="lorem ipsum content">My div or button or something with popover</button>  _x000D_

SQL DATEPART(dw,date) need monday = 1 and sunday = 7

I would suggest that you just write the case statement yourself using datename():

select (case datename(dw,
             when 'Monday' then 1
             when 'Tuesday' then 2
             when 'Wednesday' then 3
             when 'Thursday' then 4
             when 'Friday' then 5
             when 'Saturday' then 6
             when 'Sunday' then 7

At least, this won't change if someone changes the parameter on the day of the week when weeks begin. On the other hand, it is susceptible to the language chosen for SQL Server.

How to execute a file within the python interpreter?

Supposing you desire the following features:

  1. Source file behaves properly in your debugger (filename shows in stack, etc)
  2. __name__ == '__main__' is True so scripts behave properly as scripts.

The exec(open('').read()) fails feature 1 The import foo strategy fails feature 2

To get both, you need this:

    source = open(filename).read()
    code = compile(source, filename, 'exec')

Return string Input with parse.string

If you're really bent upon converting Integer to String value, I suggest use String.valueOf(YourIntegerVariable). More details can be found at:

How to upgrade Git to latest version on macOS?

The latest version was not available as a binary for mac on, so I installed from source. I was missing a required package for localization, and added NO_GETTEXT=true to install without localization.

git clone
cd git
make NO_GETTEXT=true
make NO_GETTEXT=true install

This installed git under ~/bin which I then had to add to the beginning of my PATH variable.

How to see the actual Oracle SQL statement that is being executed

I had (have) a similar problem in a Java application. I wrote a JDBC driver wrapper around the Oracle driver so all output is sent to a log file.

bodyParser is deprecated express 4

Want zero warnings? Use it like this:

  extended: true

Explanation: The default value of the extended option has been deprecated, meaning you need to explicitly pass true or false value.

bootstrap responsive table content wrapping

The behaviour is on purpose:

Create responsive tables by wrapping any .table in .table-responsive to make them scroll horizontally on small devices (under 768px). When viewing on anything larger than 768px wide, you will not see any difference in these tables.

Which means tables are responsive by default (are adjusting their size). But only if you wish to not break your table's lines and add scrollbar when there is not enough room use .table-responsive class.

If you take a look at bootstrap's source you will notice there is media query that only activates on XS screen size and it sets text of table to white-space: nowrap which causes it to not breaking.

TL;DR; Solution

Simply remove .table-responsive element/class from your html code.

Reorder / reset auto increment primary key

You can remove the primary key auto increment functionality of that column, then every time you update that column run a query before hand that will count all the rows in the table, then run a loop that iterates through that row count inserting each value into the respective row, and finally run a query inserting a new row with the value of that column being the total row count plus one. This will work flawlessly and is the most absolute solution to someone trying to accomplish what you are. Here is an example of code you may use for the function:

$table_row_count = mysql_result(mysql_query("SELECT COUNT(`field_1`) FROM `table`"), 0);
$viewsrowsdata = mysql_query("
    SELECT `rank`, `field1`, `field2`, `field3`, `field4`
        FROM (SELECT (@rank:=@rank+1) as `rank`, `field1`, `field2`, `field3`, `field4`
            FROM (SELECT * FROM `views`) a
            CROSS JOIN (SELECT @rank:=0) b
            ORDER BY rank ASC) c
while ($row = mysql_fetch_assoc($viewsrowsdata)) {
    $data[] = $row;
foreach ($data as $row) {
    $new_field_1 = (int)$row['rank'];
    $old_field_1 = (int)$row['field1'];
    mysql_query("UPDATE `table` SET `field_1` = $new_field_1 WHERE `field_1` = $old_field_1");
mysql_query("INSERT INTO `table` (`field1`, `field2`, `field3`, `field4`) VALUES ('$table_row_count' + 1, '$field_2_value', 'field_3_value', 'field_4_value')");

Here I created an associative array which I had appended on a rank column with the query within a select query, which gave each row a rank value starting with 1. I then iterated through the associative array.

Another option would have been to get the row count, run a basic select query, get the associative array and iterate it through the same way but with an added variable that updates through each iteration. This is less flexible but will accomplish the same thing.

$table_row_count = mysql_result(mysql_query("SELECT COUNT(`field_1`) FROM `table`"), 0);
$viewsrowsdata = mysql_query("SELECT * FROM `table`");
$updated_key = 0;
while ($row = mysql_fetch_assoc($viewsrowsdata)) {
    $data[] = $row;
foreach ($data as $row) {
    $updated_key = $updated_key + 1;
    mysql_query("UPDATE `table` SET `field_1` = '$updated_key' WHERE `field_1` = '$row['field_1']'");
mysql_query("INSERT INTO `table` (`field1`, `field2`, `field3`, `field4`) VALUES ('$table_row_count' + 1, '$field_2_value', 'field_3_value', 'field_4_value')");

Can I hide the HTML5 number input’s spin box?

Short answer:

input[type="number"]::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
input[type="number"] {
    -moz-appearance: textfield;
<input type="number" />

Longer answer:

To add to existing answer...


In current versions of Firefox, the (user agent) default value of the -moz-appearance property on these elements is number-input. Changing that to the value textfield effectively removes the spinner.

input[type="number"] {
    -moz-appearance: textfield;

In some cases, you may want the spinner to be hidden initially, and then appear on hover/focus. (This is currently the default behavior in Chrome). If so, you can use the following:

input[type="number"] {
    -moz-appearance: textfield;
input[type="number"]:focus {
    -moz-appearance: number-input;
<input type="number"/>


In current versions of Chrome, the (user agent) default value of the -webkit-appearance property on these elements is already textfield. In order to remove the spinner, the -webkit-appearance property's value needs to be changed to none on the ::-webkit-outer-spin-button/::-webkit-inner-spin-button pseudo classes (it is -webkit-appearance: inner-spin-button by default).

input[type="number"]::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
<input type="number" />

It's worth pointing out that margin: 0 is used to remove the margin in older versions of Chrome.

Currently, as of writing this, here is the default user agent styling on the 'inner-spin-button' pseudo class:

input::-webkit-inner-spin-button {
    -webkit-appearance: inner-spin-button;
    display: inline-block;
    cursor: default;
    flex: 0 0 auto;
    align-self: stretch;
    -webkit-user-select: none;
    opacity: 0;
    pointer-events: none;
    -webkit-user-modify: read-only;

Get local href value from anchor (a) tag

The href property sets or returns the value of the href attribute of a link.

  var hello = domains[i].getElementsByTagName('a')[0].getAttribute('href');
    var url="";
    console.log( url+hello);

Inserting data into a temporary table

After you create the temp table you would just do a normal INSERT INTO () SELECT FROM

INSERT INTO #TempTable (id, Date, Name)
SELECT, t.Date, t.Name
FROM yourTable t

Is there an upper bound to BigInteger?

BigInteger would only be used if you know it will not be a decimal and there is a possibility of the long data type not being large enough. BigInteger has no cap on its max size (as large as the RAM on the computer can hold).

From here.

It is implemented using an int[]:

  110       /**
  111        * The magnitude of this BigInteger, in <i>big-endian</i> order: the
  112        * zeroth element of this array is the most-significant int of the
  113        * magnitude.  The magnitude must be "minimal" in that the most-significant
  114        * int ({@code mag[0]}) must be non-zero.  This is necessary to
  115        * ensure that there is exactly one representation for each BigInteger
  116        * value.  Note that this implies that the BigInteger zero has a
  117        * zero-length mag array.
  118        */
  119       final int[] mag;

From the source

From the Wikipedia article Arbitrary-precision arithmetic:

Several modern programming languages have built-in support for bignums, and others have libraries available for arbitrary-precision integer and floating-point math. Rather than store values as a fixed number of binary bits related to the size of the processor register, these implementations typically use variable-length arrays of digits.

Execution order of events when pressing PrimeFaces p:commandButton

I just love getting information like BalusC gives here - and he is kind enough to help SO many people with such GOOD information that I regard his words as gospel, but I was not able to use that order of events to solve this same kind of timing issue in my project. Since BalusC put a great general reference here that I even bookmarked, I thought I would donate my solution for some advanced timing issues in the same place since it does solve the original poster's timing issues as well. I hope this code helps someone:

        <p:pickList id="formPickList" 
                    itemValue="#{mediaFiles}" >
            <f:facet name="sourceCaption">Available Media</f:facet>
            <f:facet name="targetCaption">Chosen Media</f:facet>

        <p:commandButton id="viewStream_btn" 
                         value="Stream chosen media" 
                         icon="fa fa-download"
                         style="margin-top:5px" >
            <p:ajax process="formPickList"  />

The dialog is at the top of the XHTML outside this form and it has a form of its own embedded in the dialog along with a datatable which holds additional commands for streaming the media that all needed to be primed and ready to go when the dialog is presented. You can use this same technique to do things like download customized documents that need to be prepared before they are streamed to the user's computer via fileDownload buttons in the dialog box as well.

As I said, this is a more complicated example, but it hits all the high points of your problem and mine. When the command button is clicked, the result is to first insure the backing bean is updated with the results of the pickList, then tell the backing bean to prepare streams for the user based on their selections in the pick list, then update the controls in the dynamic dialog with an update, then show the dialog box ready for the user to start streaming their content.

The trick to it was to use BalusC's order of events for the main commandButton and then to add the <p:ajax process="formPickList" /> bit to ensure it was executed first - because nothing happens correctly unless the pickList updated the backing bean first (something that was not happening for me before I added it). So, yea, that commandButton rocks because you can affect previous, pending and current components as well as the backing beans - but the timing to interrelate all of them is not easy to get a handle on sometimes.

Happy coding!

Swift convert unix time to date and time

func timeStringFromUnixTime(unixTime: Double) -> String {
    let date = NSDate(timeIntervalSince1970: unixTime)

    // Returns date formatted as 12 hour time.
    dateFormatter.dateFormat = "hh:mm a"
    return dateFormatter.stringFromDate(date)

func dayStringFromTime(unixTime: Double) -> String {
    let date = NSDate(timeIntervalSince1970: unixTime)
    dateFormatter.locale = NSLocale(localeIdentifier: NSLocale.currentLocale().localeIdentifier)
    dateFormatter.dateFormat = "EEEE"
    return dateFormatter.stringFromDate(date)

Converting a PDF to PNG

Couldn't get the accepted answer to work. Then found out that actually the solution is much simpler anyway as Ghostscript not just natively supports PNG but even multiple different "encodings":

  • png256
  • png16
  • pnggray
  • pngmono
  • ...

The shell command that works for me is:

gs -dNOPAUSE -q -sDEVICE=pnggray -r500 -dBATCH -dFirstPage=2 -dLastPage=2 -sOutputFile=test.png test.pdf

It will save page 2 of test.pdf to test.png using the pnggray encoding and 500 DPI.

How to format code in Xcode?

Select first the text you want to format and then press Ctrl+I.

Use Cmd+A first if you wish to format all text in the selected file.

Note: this procedure only re-indents the lines, it does not do any advanced formatting.

In XCode 12 beta:

The new key binding to re-indent is control+I.

finding multiples of a number in Python

For the first ten multiples of 5, say

>>> [5*n for n in range(1,10+1)]
[5, 10, 15, 20, 25, 30, 35, 40, 45, 50]

How do I navigate to a parent route from a child route?

None of this worked for me ... Here is my code with the back function :

import { Router } from '@angular/router';
constructor(private router: Router) {}
back() {
   this.router.navigate([this.router.url.substring(0, this.router.url.lastIndexOf('/'))]);

this.router.url.substring(0, this.router.url.lastIndexOf('/') --> get the last part of the current url after the "/" --> get the current route.

How to check if a URL exists or returns 404 with Java?

Based on the given answers and information in the question, this is the code you should use:

public static boolean doesURLExist(URL url) throws IOException
    // We want to check the current URL

    HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();

    // We don't need to get data

    // Some websites don't like programmatic access so pretend to be a browser
    httpURLConnection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv: Gecko/20090729 Firefox/3.5.2 (.NET CLR 3.5.30729)");
    int responseCode = httpURLConnection.getResponseCode();

    // We only accept response code 200
    return responseCode == HttpURLConnection.HTTP_OK;

Of course tested and working.

jquery data selector

I want to warn you that $('a[data-attribute=true]') doesn't work, as per Ashley's reply, if you attached data to a DOM element via the data() function.

It works as you'd expect if you added an actual data-attr in your HTML, but jQuery stores the data in memory, so the results you'd get from $('a[data-attribute=true]') would not be correct.

You'll need to use the data plugin, use Dmitri's filter solution, or do a $.each over all the elements and check .data() iteratively

POST request send json data java HttpUrlConnection

private JSONObject uploadToServer() throws IOException, JSONException {
            String query = "";
            String json = "{\"key\":1}";

            URL url = new URL(query);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestProperty("Content-Type", "application/json; charset=UTF-8");

            OutputStream os = conn.getOutputStream();

            // read the response
            InputStream in = new BufferedInputStream(conn.getInputStream());
            String result =, "UTF-8");
            JSONObject jsonObject = new JSONObject(result);


            return jsonObject;

Implementing Singleton with an Enum (in Java)

In this Java best practices book by Joshua Bloch, you can find explained why you should enforce the Singleton property with a private constructor or an Enum type. The chapter is quite long, so keeping it summarized:

Making a class a Singleton can make it difficult to test its clients, as it’s impossible to substitute a mock implementation for a singleton unless it implements an interface that serves as its type. Recommended approach is implement Singletons by simply make an enum type with one element:

// Enum singleton - the preferred approach
public enum Elvis {
public void leaveTheBuilding() { ... }

This approach is functionally equivalent to the public field approach, except that it is more concise, provides the serialization machinery for free, and provides an ironclad guarantee against multiple instantiation, even in the face of sophisticated serialization or reflection attacks.

While this approach has yet to be widely adopted, a single-element enum type is the best way to implement a singleton.

How to enter special characters like "&" in oracle database?

you can simply escape & by following a dot. try this:

INSERT INTO STUDENT(name, class_id) VALUES ('Samantha', 'Java_22 &. Oracle_14');

Efficient way to do batch INSERTS with JDBC

This is a mix of the two previous answers:

  PreparedStatement ps = c.prepareStatement("INSERT INTO employees VALUES (?, ?)");

  ps.setString(1, "John");

  ps.setString(1, "Dave");

  int[] results = ps.executeBatch();

jQuery AJAX cross domain

This is possible, but you need to use JSONP, not JSON. Stefan's link pointed you in the right direction. The jQuery AJAX page has more information on JSONP.

Remy Sharp has a detailed example using PHP.

How do I create a new branch?

Branches in SVN are essentially directories; you don't name the branch so much as choose the name of the directory to branch into.

The common way of 'naming' a branch is to place it under a directory called branches in your repository. In the "To URL:" portion of TortoiseSVN's Branch dialog, you would therefore enter something like:


The main branch of a project is referred to as the trunk, and is usually located in:


How to get equal width of input and select fields

Updated answer

Here is how to change the box model used by the input/textarea/select elements so that they all behave the same way. You need to use the box-sizing property which is implemented with a prefix for each browser


This means that the 2px difference we mentioned earlier does not exist..

example at

note: On IE it works from version 8 and upwards..


if you reset their borders then the select element will always be 2 pixels less than the input elements..


IE8 support for CSS Media Query

css3-mediaqueries-js is probably what you are looking for: this script emulates media queries. However (from the script's site) it "doesn't work on @imported stylesheets (which you shouldn't use anyway for performance reasons). Also won't listen to the media attribute of the <link> and <style> elements".

In the same vein you have the simpler Respond.js, which enables only min-width and max-width media queries.

How to disassemble a binary executable in Linux to get the assembly code?

This answer is specific to x86. Portable tools that can disassemble AArch64, MIPS, or whatever machine code include objdump and llvm-objdump.

Agner Fog's disassembler, objconv, is quite nice. It will add comments to the disassembly output for performance problems (like the dreaded LCP stall from instructions with 16bit immediate constants, for example).

objconv  -fyasm a.out /dev/stdout | less

(It doesn't recognize - as shorthand for stdout, and defaults to outputting to a file of similar name to the input file, with .asm tacked on.)

It also adds branch targets to the code. Other disassemblers usually disassemble jump instructions with just a numeric destination, and don't put any marker at a branch target to help you find the top of loops and so on.

It also indicates NOPs more clearly than other disassemblers (making it clear when there's padding, rather than disassembling it as just another instruction.)

It's open source, and easy to compile for Linux. It can disassemble into NASM, YASM, MASM, or GNU (AT&T) syntax.

Sample output:

; Filling space: 0FH
; Filler type: Multi-byte NOP
;       db 0FH, 1FH, 44H, 00H, 00H, 66H, 2EH, 0FH
;       db 1FH, 84H, 00H, 00H, 00H, 00H, 00H

ALIGN   16

foo:    ; Function begin
        cmp     rdi, 1                                  ; 00400620 _ 48: 83. FF, 01
        jbe     ?_026                                   ; 00400624 _ 0F 86, 00000084
        mov     r11d, 1                                 ; 0040062A _ 41: BB, 00000001
?_020:  mov     r8, r11                                 ; 00400630 _ 4D: 89. D8
        imul    r8, r11                                 ; 00400633 _ 4D: 0F AF. C3
        add     r8, rdi                                 ; 00400637 _ 49: 01. F8
        cmp     r8, 3                                   ; 0040063A _ 49: 83. F8, 03
        jbe     ?_029                                   ; 0040063E _ 0F 86, 00000097
        mov     esi, 1                                  ; 00400644 _ BE, 00000001
; Filling space: 7H
; Filler type: Multi-byte NOP
;       db 0FH, 1FH, 80H, 00H, 00H, 00H, 00H

?_021:  add     rsi, rsi                                ; 00400650 _ 48: 01. F6
        mov     rax, rsi                                ; 00400653 _ 48: 89. F0
        imul    rax, rsi                                ; 00400656 _ 48: 0F AF. C6
        shl     rax, 2                                  ; 0040065A _ 48: C1. E0, 02
        cmp     r8, rax                                 ; 0040065E _ 49: 39. C0
        jnc     ?_021                                   ; 00400661 _ 73, ED
        lea     rcx, [rsi+rsi]                          ; 00400663 _ 48: 8D. 0C 36

Note that this output is ready to be assembled back into an object file, so you can tweak the code at the asm source level, rather than with a hex-editor on the machine code. (So you aren't limited to keeping things the same size.) With no changes, the result should be near-identical. It might not be, though, since disassembly of stuff like

  (from /lib/x86_64-linux-gnu/

SECTION .plt    align=16 execute                        ; section number 11, code

?_00001:; Local function
        push    qword [rel ?_37996]                     ; 0001F420 _ FF. 35, 003A4BE2(rel)
        jmp     near [rel ?_37997]                      ; 0001F426 _ FF. 25, 003A4BE4(rel)

?_00002:jmp     near [rel ?_37998]                      ; 0001F430 _ FF. 25, 003A4BE2(rel)

; Note: Immediate operand could be made smaller by sign extension
        push    11                                      ; 0001F436 _ 68, 0000000B
; Note: Immediate operand could be made smaller by sign extension
        jmp     ?_00001                                 ; 0001F43B _ E9, FFFFFFE0

doesn't have anything in the source to make sure it assembles to the longer encoding that leaves room for relocations to rewrite it with a 32bit offset.

If you don't want to install it objconv, GNU binutils objdump -Mintel -d is very usable, and will already be installed if you have a normal Linux gcc setup.

jQuery: how do I animate a div rotation?

If you want just a jQuery option, this will work:

  {rotation: 360},
    duration: 500,
    step: function(now, fx) {
      $(this).css({"transform": "rotate("+now+"deg)"});

This works with jQuery 1.8, which takes care of CSS prefixing automatically. jQuery doesn't animate rotation so I'm putting the transform:rotate() in the custom step function. It might only work starting from 0.


IE9 and Mobile Safari 4 support CSS transforms but not CSS transitions, so I came up with this simple shim, using Modernizr feature testing:

if (Modernizr.csstransitions) {
    "transition": "all 500ms ease-in-out"

  var rotateTo = 360;
  if (Modernizr.csstransitions) {
    $(el).css({"transform": "rotate("+rotateTo+"deg)"});
  } else {
      {rotation: rotateTo},
        duration: 500,
        step: function(now, fx) {
          $(this).css({"transform": "rotate("+now+"deg)"});

The above will use CSS transitions when available.

When to use SELECT ... FOR UPDATE?

The only portable way to achieve consistency between rooms and tags and making sure rooms are never returned after they had been deleted is locking them with SELECT FOR UPDATE.

However in some systems locking is a side effect of concurrency control, and you achieve the same results without specifying FOR UPDATE explicitly.

To solve this problem, Thread 1 should SELECT id FROM rooms FOR UPDATE, thereby preventing Thread 2 from deleting from rooms until Thread 1 is done. Is that correct?

This depends on the concurrency control your database system is using.

  • MyISAM in MySQL (and several other old systems) does lock the whole table for the duration of a query.

  • In SQL Server, SELECT queries place shared locks on the records / pages / tables they have examined, while DML queries place update locks (which later get promoted to exclusive or demoted to shared locks). Exclusive locks are incompatible with shared locks, so either SELECT or DELETE query will lock until another session commits.

  • In databases which use MVCC (like Oracle, PostgreSQL, MySQL with InnoDB), a DML query creates a copy of the record (in one or another way) and generally readers do not block writers and vice versa. For these databases, a SELECT FOR UPDATE would come handy: it would lock either SELECT or the DELETE query until another session commits, just as SQL Server does.

When should one use REPEATABLE_READ transaction isolation versus READ_COMMITTED with SELECT ... FOR UPDATE?

Generally, REPEATABLE READ does not forbid phantom rows (rows that appeared or disappeared in another transaction, rather than being modified)

  • In Oracle and earlier PostgreSQL versions, REPEATABLE READ is actually a synonym for SERIALIZABLE. Basically, this means that the transaction does not see changes made after it has started. So in this setup, the last Thread 1 query will return the room as if it has never been deleted (which may or may not be what you wanted). If you don't want to show the rooms after they have been deleted, you should lock the rows with SELECT FOR UPDATE

  • In InnoDB, REPEATABLE READ and SERIALIZABLE are different things: readers in SERIALIZABLE mode set next-key locks on the records they evaluate, effectively preventing the concurrent DML on them. So you don't need a SELECT FOR UPDATE in serializable mode, but do need them in REPEATABLE READ or READ COMMITED.

Note that the standard on isolation modes does prescribe that you don't see certain quirks in your queries but does not define how (with locking or with MVCC or otherwise).

When I say "you don't need SELECT FOR UPDATE" I really should have added "because of side effects of certain database engine implementation".

What is Join() in jQuery?

I use join to separate the word in array with "and, or , / , &"



<p>London Mexico Canada</p>


 newText = $("p").text().split(" ").join(" or ");


London or Mexico or Canada

How to convert FileInputStream to InputStream?

InputStream is = new FileInputStream("c://filename");
return is;

How to install pandas from pip on windows cmd?

If you are a windows user:
make sure you added the script(dir) path to environment variables
for more how to set path vist

How to disable HTML button using JavaScript?

The official way to set the disabled attribute on an HTMLInputElement is this:

var input = document.querySelector('[name="myButton"]');
// Without querySelector API
// var input = document.getElementsByName('myButton').item(0);

// disable
input.setAttribute('disabled', true);
// enable

While @kaushar's answer is sufficient for enabling and disabling an HTMLInputElement, and is probably preferable for cross-browser compatibility due to IE's historically buggy setAttribute, it only works because Element properties shadow Element attributes. If a property is set, then the DOM uses the value of the property by default rather than the value of the equivalent attribute.

There is a very important difference between properties and attributes. An example of a true HTMLInputElement property is input.value, and below demonstrates how shadowing works:

var input = document.querySelector('#test');_x000D_
// the attribute works as expected_x000D_
console.log('old attribute:', input.getAttribute('value'));_x000D_
// the property is equal to the attribute when the property is not explicitly set_x000D_
console.log('old property:', input.value);_x000D_
// change the input's value property_x000D_
input.value = "My New Value";_x000D_
// the attribute remains there because it still exists in the DOM markup_x000D_
console.log('new attribute:', input.getAttribute('value'));_x000D_
// but the property is equal to the set value due to the shadowing effect_x000D_
console.log('new property:', input.value);
<input id="test" type="text" value="Hello World" />

That is what it means to say that properties shadow attributes. This concept also applies to inherited properties on the prototype chain:

function Parent() {_x000D_ = 'ParentInstance';_x000D_
_x000D_ = 'ParentPrototype';_x000D_
// ES5 inheritance_x000D_
Child.prototype = Object.create(Parent.prototype);_x000D_
Child.prototype.constructor = Child;_x000D_
function Child() {_x000D_
  // ES5 super()_x000D_;_x000D_
_x000D_ = 'ChildInstance';_x000D_
_x000D_ = 'ChildPrototype';_x000D_
logChain('new Parent()');_x000D_
logChain('new Child()');_x000D_
// below is for demonstration purposes_x000D_
// don't ever actually use document.write(), eval(), or access __proto___x000D_
function log(value) {_x000D_
function logChain(code) {_x000D_
  var object = eval(code);_x000D_
  do {_x000D_
    log(`${} ${object instanceof object.constructor ? 'instance' : 'prototype'} property: ${JSON.stringify(}`);_x000D_
    object = object.__proto__;_x000D_
  } while (object !== null);_x000D_

I hope this clarifies any confusion about the difference between properties and attributes.

How to run a stored procedure in oracle sql developer?

-- If no parameters need to be passed to a procedure, simply:


Why is this error, 'Sequence contains no elements', happening?

Check again. Use debugger if must. My guess is that for some item in userResponseDetails this query finds no elements:

.Where(y => y.ResponseId.Equals(item.ResponseId))

so you can't call


on it. Maybe try


if it solves the issue.

Do NOT return NULL value! This is purely so that you can see and diagnose where problem is. Handle these cases properly.

Which selector do I need to select an option by its text?

I tried a few of these things until I got one to work in both Firefox and IE. This is what I came up with.

$("#my-Select").val($("#my-Select" + " option").filter(function() { return this.text == myText }).val());

another way of writing it in a more readable fasion:

var valofText = $("#my-Select" + " option").filter(function() {
    return this.text == myText


$("#my-Select").val( getValOfText( myText ) );

Count words in a string method?

create variable count, state. initialize variables
if space is present keep count as it is else increase count. for eg:

if (string.charAt(i) == ' ' ) {
state = 0;
} else if (state == 0) {
state = 1;
count += 1;

calling a function from class in python - different way

Your methods don't refer to an object (that is, self), so you should use the @staticmethod decorator:

class MathsOperations:
    def testAddition (x, y):
        return x + y

    def testMultiplication (a, b):
        return a * b

How do I make HttpURLConnection use a proxy?

The approved answer will work ... if you know your proxy host and port =) . But in case you are looking for the proxy host and port the steps below should help

if auto configured proxy is given: then

1> open IE(or any browser)

2> get the url address from your browser through IE->Tools->internet option->connections->LAN Settings-> get address and give in url eg: as and enter, a file will be downloaded with .pac format, save to desktop

3> open .pac file in textpad, identify PROXY:

In your editor, it will come something like:

return "PROXY; PROXY";

kudos to bekur from maven in 5 min not working

Once you have the host and port just pop in into this and your good to go

Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("", 8080));
        URLConnection connection = new URL(url).openConnection(proxy);

Reactjs convert html string to jsx

If you know ahead what tags are in the string you want to render; this could be for example if only certain tags are allowed in the moment of the creation of the string; a possible way to address this is use the Trans utility:

import { Trans } from 'react-i18next'
import React, { FunctionComponent } from "react";

export type MyComponentProps = {
    htmlString: string

export const MyComponent: FunctionComponent<MyComponentProps> = ({
}) => {
  return (
          b: <b />,
          p: <p />

then you can use it as always

    htmlString={'<p>Hello <b>World</b></p>'}

Reading and writing binary file

There is a much simpler way. This does not care if it is binary or text file.

Use noskipws.

char buf[SZ];
ifstream f("file");
int i;
for(i=0; f >> noskipws >> buffer[i]; i++);
ofstream f2("writeto");
for(int j=0; j < i; j++) f2 << noskipws << buffer[j];

Or you can just use string instead of the buffer.

string s; char c;
ifstream f("image.jpg");
while(f >> noskipws >> c) s += c;
ofstream f2("copy.jpg");
f2 << s;

normally stream skips white space characters like space or new line, tab and all other control characters. But noskipws makes all the characters transferred. So this will not only copy a text file but also a binary file. And stream uses buffer internally, I assume the speed won't be slow.

How to disable Google Chrome auto update?

On Windows OS:

1) open following file for edit (as an admin): C:\Windows\System32\drivers\etc\hosts (this file has no extension)

2) on the bottom, add one line:

3) save the file

4) enjoy old Chrome

Maximum concurrent connections to MySQL

You might have 10,000 users total, but that's not the same as concurrent users. In this context, concurrent scripts being run.

For example, if your visitor visits index.php, and it makes a database query to get some user details, that request might live for 250ms. You can limit how long those MySQL connections live even further by opening and closing them only when you are querying, instead of leaving it open for the duration of the script.

While it is hard to make any type of formula to predict how many connections would be open at a time, I'd venture the following:

You probably won't have more than 500 active users at any given time with a user base of 10,000 users. Of those 500 concurrent users, there will probably at most be 10-20 concurrent requests being made at a time.

That means, you are really only establishing about 10-20 concurrent requests.

As others mentioned, you have nothing to worry about in that department.

WPF binding to Listbox selectedItem

since you set your itemsource to your collection, your textbox is tied to each individual item in that collection. the selected item property is useful in this scenario if you were trying to do a master-detail form, having 2 listboxes. you would bind the second listbox's itemsource to the child collection of rules. in otherwords the selected item alerts outside controls that your source has changed, internal controls(those inside your datatemplate already are aware of the change.

and to answer your question yes in most circumstances setting the itemsource is the same as setting the datacontext of the control.

Windows batch - concatenate multiple text files into one

I am reiterating some of the other points already made, but including a 3rd example that helps when you have files across folders that you want to concatenate.

Example 1 (files in the same folder):

copy file1.txt+file2.txt+file3.txt file123.txt

Example 2 (files in same folder):

type *.txt > combined.txt

Example 3 (files exist across multiple folders, assumes newfileoutput.txt doesn't exist):

for /D %f in (folderName) DO type %f/filename.txt >> .\newfileoutput.txt

How to check if a variable is set in Bash?

Here's how to test whether a parameter is unset, or empty ("Null") or set with a value:

|   Expression       |       parameter      |     parameter   |    parameter    |
|   in script:       |   Set and Not Null   |   Set But Null  |      Unset      |
| ${parameter:-word} | substitute parameter | substitute word | substitute word |
| ${parameter-word}  | substitute parameter | substitute null | substitute word |
| ${parameter:=word} | substitute parameter | assign word     | assign word     |
| ${parameter=word}  | substitute parameter | substitute null | assign word     |
| ${parameter:?word} | substitute parameter | error, exit     | error, exit     |
| ${parameter?word}  | substitute parameter | substitute null | error, exit     |
| ${parameter:+word} | substitute word      | substitute null | substitute null |
| ${parameter+word}  | substitute word      | substitute word | substitute null |

Source: POSIX: Parameter Expansion:

In all cases shown with "substitute", the expression is replaced with the value shown. In all cases shown with "assign", parameter is assigned that value, which also replaces the expression.

To show this in action:

|   Expression       |  FOO="world"         |     FOO=""      |    unset FOO    |
|   in script:       |  (Set and Not Null)  |  (Set But Null) |     (Unset)     |
| ${FOO:-hello}      | world                | hello           | hello           |
| ${FOO-hello}       | world                | ""              | hello           |
| ${FOO:=hello}      | world                | FOO=hello       | FOO=hello       |
| ${FOO=hello}       | world                | ""              | FOO=hello       |
| ${FOO:?hello}      | world                | error, exit     | error, exit     |
| ${FOO?hello}       | world                | ""              | error, exit     |
| ${FOO:+hello}      | hello                | ""              | ""              |
| ${FOO+hello}       | hello                | hello           | ""              |

rename the columns name after cbind the data

If you pass only vectors to cbind() it creates a matrix, not a dataframe. Read ?data.frame.

How to set the opacity/alpha of a UIImage?

same result as others, different style:

extension UIImage {

    func withAlpha(_ alpha: CGFloat) -> UIImage {
        return UIGraphicsImageRenderer(size: size).image { _ in
            draw(at: .zero, blendMode: .normal, alpha: alpha)


How to see top processes sorted by actual memory usage?

First you should read an explanation on the output of free. Bottom line: you have at least 10.7 GB of memory readily usable by processes.

Then you should define what "memory usage" is for a process (it's not easy or unambiguous, trust me).

Then we might be able to help more :-)

How to use '-prune' option of 'find' in sh?

There are quite a few answers; some of them are a bit too much theory-heavy. I'll leave why I needed prune once so maybe the need-first/example kind of explanation is useful to someone :)


I had a folder with about 20 node directories, each having its node_modules directory as expected.

Once you get into any project, you see each ../node_modules/module. But you know how it is. Almost every module has dependencies, so what you are looking at is more like projectN/node_modules/moduleX/node_modules/moduleZ...

I didn't want to drown with a list with the dependency of the dependency of...

Knowing -d n / -depth n, it wouldn't have helped me, as the main/first node_modules directory I wanted of each project was at a different depth, like this:


How can I get the first a list of paths ending at the first node_modules and move to the next project to get the same?

Enter -prune

When you add -prune, you'll still have a standard recursive search. Each "path" is analyzed, and every find gets spit out and find keeps digging down like a good chap. But it's the digging down for more node_modules what I didn't want.

So, the difference is that in any of those different paths, -prune will find to stop digging further down that particular avenue when it has found your item. In my case, the node_modules folder.

How to sort an array of integers correctly

For a normal array of elements values only:

function sortArrayOfElements(arrayToSort) {
    function compareElements(a, b) {
        if (a < b)
            return -1;
        if (a > b)
            return 1;
        return 0;

    return arrayToSort.sort(compareElements);

e.g. 1:
var array1 = [1,2,545,676,64,2,24]
**output : [1, 2, 2, 24, 64, 545, 676]**

var array2 = ["v","a",545,676,64,2,"24"]
**output: ["a", "v", 2, "24", 64, 545, 676]**

For an array of objects:

function sortArrayOfObjects(arrayToSort, key) {
    function compareObjects(a, b) {
        if (a[key] < b[key])
            return -1;
        if (a[key] > b[key])
            return 1;
        return 0;

    return arrayToSort.sort(compareObjects);

e.g. 1: var array1= [{"name": "User4", "value": 4},{"name": "User3", "value": 3},{"name": "User2", "value": 2}]

**output : [{"name": "User2", "value": 2},{"name": "User3", "value": 3},{"name": "User4", "value": 4}]**

How to calculate sum of a formula field in crystal Reports?

You can try like this:


It will work without creating a summarize field in formulae.

How to edit a text file in my terminal

Open the file again using vi. and then press " i " or press insert key ,

For save and quit

  Enter Esc    

and write the following command


without save and quit


Rollback a Git merge

Just reset the merge commit with git reset --hard HEAD^.

If you use --no-ff git always creates a merge, even if you did not commit anything in between. Without --no-ff git will just do a fast forward, meaning your branches HEAD will be set to HEAD of the merged branch. To resolve this find the commit-id you want to revert to and git reset --hard $COMMITID.

How to output MySQL query results in CSV format?

If you are on production or any other server with no access to file system, you can use this simple trick and a little bit of manual effort to get what you want.

Step 1. Just wrap all the columns under CONCAT and use as CSVFormat option provided by MySQL to get comma-delimited results. (or use any delimiter you want). Here is an example:

            ua.longitude) AS CSVFormat
    table1 u
        LEFT JOIN
    table2 ua ON u.address_id =
    role_policy = 31 and is_active = 1;

Step 2. Copy results from your terminal to a file and clean up all the pipe characters (that forms the layout of your results) using any text editor.

Step 3. Save as .csv file and that's it.

How to convert current date into string in java?

Faster :

String date = FastDateFormat.getInstance("dd-MM-yyyy").format(System.currentTimeMillis( ));

Anaconda / Python: Change Anaconda Prompt User Path

Go to Start and search for "Anaconda Prompt" - right click this and choose "Open File Location", which will open a folder of shortcuts. Right click the "Anaconda Prompt" shortcut, choose "Properties" and you can adjust the starting dir in the "Start in" box.

How to disable Paste (Ctrl+V) with jQuery?

  $('#txtInput').live("cut copy paste",function(e) {

On textbox live event cut, copy, paste event is prevented and it works well.

EXC_BAD_ACCESS signal received

An EXC_BAD_ACCESS signal is the result of passing an invalid pointer to a system call. I got one just earlier today with a test program on OS X - I was passing an uninitialized variable to pthread_join(), which was due to an earlier typo.

I'm not familiar with iPhone development, but you should double-check all your buffer pointers that you're passing to system calls. Crank up your compiler's warning level all the way (with gcc, use the -Wall and -Wextra options). Enable as many diagnostics on the simulator/debugger as possible.

Radio Buttons "Checked" Attribute Not Working

Hey I was also facing similar problem, in an ajax generated page.. I took generated source using Webdeveloper pluggin in FF, and checked all the inputs in the form and found out that there was another checkbox inside a hidden div(display:none) with same ID, Once I changed the id of second checkbox, it started working.. You can also try that.. and let me know the result.. cheers

Custom Authentication in ASP.Net-Core

@Manish Jain, I suggest to implement the method with boolean return:

public class UserManager

    // Additional code here...            

    public async Task<bool> SignIn(HttpContext httpContext, UserDbModel user)
        // Additional code here...            

        // Here the real authentication against a DB or Web Services or whatever 
        if (user.Email != null)
            return false;                    

        ClaimsIdentity identity = new ClaimsIdentity(this.GetUserClaims(dbUserData), CookieAuthenticationDefaults.AuthenticationScheme);
        ClaimsPrincipal principal = new ClaimsPrincipal(identity);

        // This is for give the authentication cookie to the user when authentication condition was met
        await httpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, principal);
        return true;

Laravel Advanced Wheres how to pass variable into function?

@kajetons' answer is fully functional.

You can also pass multiple variables by passing them like: use($var1, $var2)

DB::table('users')->where(function ($query) use ($activated,$var2) {
    $query->where('activated', '=', $activated);
    $query->where('var2', '>', $var2);

Remove Item in Dictionary based on Value

Dictionary<string, string> source
//functional programming - do not modify state - only create new state
Dictionary<string, string> result = source
  .Where(kvp => string.Compare(kvp.Value, "two", true) != 0)
  .ToDictionary(kvp => kvp.Key, kvp => kvp.Value)
// or you could modify state
List<string> keys = source
  .Where(kvp => string.Compare(kvp.Value, "two", true) == 0)
  .Select(kvp => kvp.Key)

foreach(string theKey in keys)