Programs & Examples On #Gae eclipse plugin

List of all unique characters in a string?

char_seen = []
for char in string:
    if char not in char_seen:

This will preserve the order in which alphabets are coming,

output will be


UITableView set to static cells. Is it possible to hide some of the cells programmatically?

Simple iOS 11 & IB/Storyboard Compatible Method

For iOS 11, I found that a modified version of Mohamed Saleh's answer worked best, with some improvements based on Apple's documentation. It animates nicely, avoids any ugly hacks or hardcoded values, and uses row heights already set in Interface Builder.

The basic concept is to set the row height to 0 for any hidden rows. Then use tableView.performBatchUpdates to trigger an animation that works consistently.

Set the cell heights

override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    if indexPath == indexPathOfHiddenCell {
        if cellIsHidden {
            return 0
    // Calling super will use the height set in your storyboard, avoiding hardcoded values
    return super.tableView(tableView, heightForRowAt: indexPath)

You'll want to make sure cellIsHidden and indexPathOfHiddenCell are set appropriately to your use case. For my code they're properties on my table view controller.

Toggling the cell

In whatever method controls the visibility (likely a button action or didSelectRow), toggle the cellIsHidden state, inside a performBatchUpdates block:

                // Use self to capture for block
                self.cellIsHidden = !self.cellIsHidden 
            }, completion: nil)

Apple recommends performBatchUpdates over beginUpdates/endUpdates whenever possible.

not None test in Python

Either of the latter two, since val could potentially be of a type that defines __eq__() to return true when passed None.

What is the difference between the operating system and the kernel?

Basically the Kernel is the interface between hardware (devices which are available in Computer) and Application software is like MS Office, Visual Studio, etc.

If I answer "what is an OS?" then the answer could be the same. Hence the kernel is the part & core of the OS.

The very sensitive tasks of an OS like memory management, I/O management, process management are taken care of by the kernel only.

So the ultimate difference is:

  1. Kernel is responsible for Hardware level interactions at some specific range. But the OS is like hardware level interaction with full scope of computer.
  2. Kernel triggers SystemCalls to tell the OS that this resource is available at this point of time. The OS is responsible to handle those system calls in order to utilize the resource.

How can I "reset" an Arduino board?

Try the following:

  1. Prepare the basic empty program (empty setup, loop, etc.)
  2. Compile it.
  3. Reset the Arduino using the hardware button on the chip
  4. Press Ctrl + U to upload your code.
  5. If unsuccessful - got to 3.

There is a delay before the boot loader starts the programs, just work on your timing. It worked for me when a bug in my Arduino's code was executing a soft reset every 500 ms.

Why am I getting an Exception with the message "Invalid setup on a non-virtual (overridable in VB) member..."?

Moq cannot mock non-virtual methods and sealed classes. While running a test using mock object, MOQ actually creates an in-memory proxy type which inherits from your "XmlCupboardAccess" and overrides the behaviors that you have set up in the "SetUp" method. And as you know in C#, you can override something only if it is marked as virtual which isn't the case with Java. Java assumes every non-static method to be virtual by default.

Another thing I believe you should consider is introducing an interface for your "CupboardAccess" and start mocking the interface instead. It would help you decouple your code and have benefits in the longer run.

Lastly, there are frameworks like : TypeMock and JustMock which work directly with the IL and hence can mock non-virtual methods. Both however, are commercial products.

Calculate number of hours between 2 dates in PHP

In addition to @fyrye's very helpful answer this is an okayish workaround for the mentioned bug (this one), that DatePeriod substracts one hour when entering summertime, but doesn't add one hour when leaving summertime (and thus Europe/Berlin's March has its correct 743 hours but October has 744 instead of 745 hours):

Counting the hours of a month (or any timespan), considering DST-transitions in both directions

function getMonthHours(string $year, string $month, \DateTimeZone $timezone): int
    // or whatever start and end \DateTimeInterface objects you like
    $start = new \DateTimeImmutable($year . '-' . $month . '-01 00:00:00', $timezone);
    $end = new \DateTimeImmutable((new \DateTimeImmutable($year . '-' . $month . '-01 23:59:59', $timezone))->format('Y-m-t H:i:s'), $timezone);
    // count the hours just utilizing \DatePeriod, \DateInterval and iterator_count, hell yeah!
    $hours = iterator_count(new \DatePeriod($start, new \DateInterval('PT1H'), $end));
    // find transitions and check, if there is one that leads to a positive offset
    // that isn't added by \DatePeriod
    // this is the workaround for
    $transitions = $timezone->getTransitions((int)$start->format('U'), (int)$end->format('U'));
    if (2 === count($transitions) && $transitions[0]['offset'] - $transitions[1]['offset'] > 0) {
        $hours += (round(($transitions[0]['offset'] - $transitions[1]['offset'])/3600));
    return $hours;

$myTimezoneWithDST = new \DateTimeZone('Europe/Berlin');
var_dump(getMonthHours('2020', '01', $myTimezoneWithDST)); // 744
var_dump(getMonthHours('2020', '03', $myTimezoneWithDST)); // 743
var_dump(getMonthHours('2020', '10', $myTimezoneWithDST)); // 745, finally!

$myTimezoneWithoutDST = new \DateTimeZone('UTC');
var_dump(getMonthHours('2020', '01', $myTimezoneWithoutDST)); // 744
var_dump(getMonthHours('2020', '03', $myTimezoneWithoutDST)); // 744
var_dump(getMonthHours('2020', '10', $myTimezoneWithoutDST)); // 744

P.S. If you check a (longer) timespan, which leads to more than those two transitions, my workaround won't touch the counted hours to reduce the potential of funny side effects. In such cases, a more complicated solution must be implemented. One could iterate over all found transitions and compare the current with the last and check if it is one with DST true->false.

java.lang.ClassNotFoundException: sun.jdbc.odbc.JdbcOdbcDriver Exception occurring. Why?

Make sure you have closed your MSAccess file before running the java program.

pip install - locale.Error: unsupported locale setting

Run the following command (it will work):

export LC_ALL="en_US.UTF-8"
export LC_CTYPE="en_US.UTF-8"
sudo dpkg-reconfigure locales

How to check if android checkbox is checked within its onClick method (declared in XML)?

try this one :

public void itemClicked(View v) {
  //code to check if this checkbox is checked!
  CheckBox checkBox = (CheckBox)v;


How to use Python requests to fake a browser visit a.k.a and generate User Agent?

The root of the answer is that the person asking the question needs to have a JavaScript interpreter to get what they are after. What I have found is I am able to get all of the information I wanted on a website in json before it was interpreted by JavaScript. This has saved me a ton of time in what would be parsing html hoping each webpage is in the same format.

So when you get a response from a website using requests really look at the html/text because you might find the javascripts JSON in the footer ready to be parsed.

Difference between Math.Floor() and Math.Truncate()

Math.Floor(): Returns the largest integer less than or equal to the specified double-precision floating-point number.

Math.Round(): Rounds a value to the nearest integer or to the specified number of fractional digits.

How to read a file line-by-line into a list?

I like to use the following. Reading the lines immediately.

contents = []
for line in open(filepath, 'r').readlines():

Or using list comprehension:

contents = [line.strip() for line in open(filepath, 'r').readlines()]

How to execute a Ruby script in Terminal?

To call ruby file use : ruby your_program.rb

To execute your ruby file as script:

  1. start your program with #!/usr/bin/env ruby

  2. run that script using ./your_program.rb param

  3. If you are not able to execute this script check permissions for file.

smtp configuration for php mail

But now it is not working and I contacted our hosting team then they told me to use smtp

Newsflash - it was using SMTP before. They've not provided you with the information you need to solve the problem - or you've not relayed it accurately here.

Its possible that they've disabled the local MTA on the webserver, in which case you'll need to connect the SMTP port on a remote machine. There are lots of toolkits which will do the heavy lifting for you. Personally I like phpmailer because it adds other functionality.

Certainly if they've taken away a facility which was there before and your paying for a service then your provider should be giving you better support than that (there are also lots of programs to drop in in place of a full MTA which would do the job).


Remove x-axis label/text in chart.js

Faced this issue of removing the labels in Chartjs now. Looks like the documentation is improved. = false;

this global settings prevents legends from being shown in all Charts. Since this was enough for me, I used it. I am not sure to how to avoid legends for individual charts.

Empty or Null value display in SSRS text boxes

Try this


How to add minutes to my Date

Once you have you date parsed, I use this utility function to add hours, minutes or seconds:

public class DateTimeUtils {
    private static final long ONE_HOUR_IN_MS = 3600000;
    private static final long ONE_MIN_IN_MS = 60000;
    private static final long ONE_SEC_IN_MS = 1000;

    public static Date sumTimeToDate(Date date, int hours, int mins, int secs) {
        long hoursToAddInMs = hours * ONE_HOUR_IN_MS;
        long minsToAddInMs = mins * ONE_MIN_IN_MS;
        long secsToAddInMs = secs * ONE_SEC_IN_MS;
        return new Date(date.getTime() + hoursToAddInMs + minsToAddInMs + secsToAddInMs);

Be careful when adding long periods of time, 1 day is not always 24 hours (daylight savings-type adjustments, leap seconds and so on), Calendar is recommended for that.

Iterate through dictionary values?

Depending on your version:

Python 2.x:

for key, val in PIX0.iteritems():
    NUM = input("Which standard has a resolution of {!r}?".format(val))
    if NUM == key:
        print ("Nice Job!")
        count = count + 1
        print("I'm sorry but thats wrong. The correct answer was: {!r}.".format(key))

Python 3.x:

for key, val in PIX0.items():
    NUM = input("Which standard has a resolution of {!r}?".format(val))
    if NUM == key:
        print ("Nice Job!")
        count = count + 1
        print("I'm sorry but thats wrong. The correct answer was: {!r}.".format(key))

You should also get in the habit of using the new string formatting syntax ({} instead of % operator) from PEP 3101:

Which Python memory profiler is recommended?

My module memory_profiler is capable of printing a line-by-line report of memory usage and works on Unix and Windows (needs psutil on this last one). Output is not very detailed but the goal is to give you an overview of where the code is consuming more memory, not an exhaustive analysis on allocated objects.

After decorating your function with @profile and running your code with the -m memory_profiler flag it will print a line-by-line report like this:

Line #    Mem usage  Increment   Line Contents
     3                           @profile
     4      5.97 MB    0.00 MB   def my_func():
     5     13.61 MB    7.64 MB       a = [1] * (10 ** 6)
     6    166.20 MB  152.59 MB       b = [2] * (2 * 10 ** 7)
     7     13.61 MB -152.59 MB       del b
     8     13.61 MB    0.00 MB       return a

How can I mock an ES6 module import using Jest?

You have to mock the module and set the spy by yourself:

import myModule from '../myModule';
import dependency from '../dependency';
jest.mock('../dependency', () => ({
  doSomething: jest.fn()

describe('myModule', () => {
  it('calls the dependency with double the input', () => {

Show div #id on click with jQuery

You can use jQuery toggle to show and hide the div. The script will be like this

  <script type="text/javascript">
      jQuery("#music").click(function () {

Git - how delete file from remote repository

If you have deleted lot of files and folders, just do this

git commit -a -m .
git push

how to implement regions/code collapse in javascript

Good news for developers who is working with latest version of visual studio

The Web Essentials are coming with this feature .

Check this out

enter image description here

Note: For VS 2017 use JavaScript Regions :

What does it mean "No Launcher activity found!"

You have not included Launcher intent filter in activity you want to appear first, so it does not know which activity to start when application launches, for this tell the system by including launcher filter intent in manifest.xml

Multiple submit buttons on HTML form – designate one button as default

Set type=submit to the button you'd like to be default and type=button to other buttons. Now in the form below you can hit Enter in any input fields, and the Render button will work (despite the fact it is the second button in the form).


    <button id='close_button' class='btn btn-success'
      <span class='glyphicon glyphicon-edit'> </span> Edit program
    <button id='render_button' class='btn btn-primary'
            type=submit>             <!--  Here we use SUBMIT, not BUTTON -->
      <span class='glyphicon glyphicon-send'> </span> Render

Tested in FF24 and Chrome 35.

Convert a bitmap into a byte array

More simple:

return (byte[])System.ComponentModel.TypeDescriptor.GetConverter(pImagen).ConvertTo(pImagen, typeof(byte[]))

ImportError: No module named PytQt5

After getting the help from @Blender, @ekhumoro and @Dan, I understand the Linux and Python more than before. Thank you. I got the an idea by @ekhumoro, it is I didn't install PyQt5 correctly. So I delete PyQt5 folder and download again. And redo everything from very start.

After redoing, I got the error as my last update at my question. So, when I search at stack, I got the following solution from here

sudo ln -s /usr/include/python2.7 /usr/local/include/python2.7

And then, I did "sudo make" and "sudo make install" step by step. After "sudo make install", I got the following error. But I ignored it and I created a simple design with qt designer. And I converted it into python file by pyuic5. Everything are going well.

install -m 755 -p /home/thura/PyQt/pyuic5 /usr/bin/
strip /usr/bin/pyuic5
strip:/usr/bin/pyuic5: File format not recognized
make: [install_pyuic5] Error 1 (ignored)

php hide ALL errors

Per the PHP documentation, put this at the top of your php scripts:

<?php error_reporting(0); ?>

If you do hide your errors, which you should in a live environment, make sure that you are logging any errors somewhere. How to log errors and warnings into a file? Otherwise, things will go wrong and you will have no idea why.

How to select a single column with Entity Framework?

I'm a complete noob on Entity but this is how I would do it in theory...

var name = yourDbContext.MyTable.Find(1).Name;

If It's A Primary Key.

-- OR --

var name = yourDbContext.MyTable.SingleOrDefault(mytable => mytable.UserId == 1).Name;

-- OR --

For whole Column:

var names = yourDbContext.MyTable
.Where(mytable => mytable.UserId == 1)
.Select(column => column.Name); //You can '.ToList();' this....

But "oh Geez Rick, What do I know..."

How do I ignore ampersands in a SQL script running from SQL Plus?

set define off <- This is the best solution I found

I also tried...

set define }

I was able to insert several records containing ampersand characters '&' but I cannot use the '}' character into the text So I decided to use "set define off" and everything works as it should.

Reading and displaying data from a .txt file

In Java 8, you can read a whole file, simply with:

public String read(String file) throws IOException {
  return new String(Files.readAllBytes(Paths.get(file)));

or if its a Resource:

public String read(String file) throws IOException {
  URL url = Resources.getResource(file);
  return Resources.toString(url, Charsets.UTF_8);

How to undo "git commit --amend" done instead of "git commit"

Maybe can use git reflog to get two commit before amend and after amend.

Then use git diff before_commit_id after_commit_id > d.diff to get diff between before amend and after amend.

Next use git checkout before_commit_id to back to before commit

And last use git apply d.diff to apply the real change you did.

That solves my problem.

Getting a File's MD5 Checksum in Java

I recently had to do this for just a dynamic string, MessageDigest can represent the hash in numerous ways. To get the signature of the file like you would get with the md5sum command I had to do something like the this:

try {
   String s = "TEST STRING";
   MessageDigest md5 = MessageDigest.getInstance("MD5");
   String signature = new BigInteger(1,md5.digest()).toString(16);
   System.out.println("Signature: "+signature);

} catch (final NoSuchAlgorithmException e) {

This obviously doesn't answer your question about how to do it specifically for a file, the above answer deals with that quiet nicely. I just spent a lot of time getting the sum to look like most application's display it, and thought you might run into the same trouble.

Starting of Tomcat failed from Netbeans

None of the answers here solved my issue (as at February 2020), so I raised an issue at and Netbeans fixed the issue!

They're working on a pull request so the fix will be in a future .dmg installer soon, but in the meantime you can copy a file referenced in the bug and replace one in your netbeans modules folder.

Tip - if you right click on Applications > Netbeans and choose Show Package Contents Show Package Contents then you can find and replace the file org-netbeans-modules-tomcat5.jar that they refer to in your Netbeans folder, e.g. within /Applications/NetBeans/Apache NetBeans

How to edit nginx.conf to increase file size upload

Add client_max_body_size

Now that you are editing the file you need to add the line into the server block, like so;

server {
    client_max_body_size 8M;

    //other lines...

If you are hosting multiple sites add it to the http context like so;

http {
    client_max_body_size 8M;

    //other lines...

And also update the upload_max_filesize in your php.ini file so that you can upload files of the same size.

Saving in Vi

Once you are done you need to save, this can be done in vi with pressing esc key and typing :wq and returning.

Restarting Nginx and PHP

Now you need to restart nginx and php to reload the configs. This can be done using the following commands;

sudo service nginx restart
sudo service php5-fpm restart

Or whatever your php service is called.

The name 'InitializeComponent' does not exist in the current context

In my case the instance of program was already running in background. I just stop the running instance and program built successfully.

TypeError: object of type 'int' has no len() error assistance needed

May be it is the problem of using len() for an integer value. does not posses the len attribute in Python.

Error as:I will give u an example:

number= 1

Instead of use ths,

data = [1,2,3,4]

View list of all JavaScript variables in Google Chrome Console

Is this the kind of output you're looking for?

for(var b in window) { 
  if(window.hasOwnProperty(b)) console.log(b); 

This will list everything available on the window object (all the functions and variables, e.g., $ and jQuery on this page, etc.). Though, this is quite a list; not sure how helpful it is...

Otherwise just do window and start going down its tree:


This will give you DOMWindow, an expandable/explorable object.

How to select last child element in jQuery?

You can also do this:

<ul id="example">

// possibility 1
$('#example li:last').val();
// possibility 2
// possibility 3
$('#example li:last-child').val();




how to instanceof List<MyType>?

This could be used if you want to check that object is instance of List<T>, which is not empty:

if(object instanceof List){
    if(((List)object).size()>0 && (((List)object).get(0) instanceof MyObject)){
        // The object is of List<MyObject> and is not empty. Do something with it.

R: += (plus equals) and ++ (plus plus) equivalent from c++/c#/java, etc.?

We can override +. If unary + is used and its argument is itself an unary + call, then increment the relevant variable in the calling environment.

`+` <- function(e1,e2){
    # if unary `+`, keep original behavior
    if(missing(e2)) {
      s_e1 <- substitute(e1)
      # if e1 (the argument of unary +) is itself an unary `+` operation
      if(length(s_e1) == 2 && 
         identical(s_e1[[1]], quote(`+`)) && 
         length(s_e1[[2]]) == 1) {
        # increment value in parent environment
        eval.parent(substitute(e1 <- e1 + 1, list(e1 = s_e1[[2]])))
      # else unary `+` should just return it's input
      } else e1
    # if binary `+`, keep original behavior
    } else .Primitive("+")(e1, e2)

x <- 10
# [1] 11

other operations don't change :

x + 2
# [1] 13
x ++ 2
# [1] 13
# [1] 11
# [1] 11

Don't do it though, as you'll slow down everything. Or do it in another environment and make sure you don't have big loops on these instructions.

You can also just do this :

`++` <- function(x) eval.parent(substitute(x <- x + 1))
a <- 1
# [1] 2

How can I format DateTime to web UTC format?

string.Format("{0:yyyy-MM-ddTHH:mm:ss.FFFZ}", DateTime.UtcNow)

returns 2017-02-10T08:12:39.483Z

jQuery show for 5 seconds then hide

You can use .delay() before an animation, like this:


If it's not an animation, use setTimeout() directly, like this:

setTimeout(function() { $("#myElem").hide(); }, 5000);

You do the second because .hide() wouldn't normally be on the animation (fx) queue without a duration, it's just an instant effect.

Or, another option is to use .delay() and .queue() yourself, like this:

$("#myElem").show().delay(5000).queue(function(n) {
  $(this).hide(); n();

How to edit one specific row in Microsoft SQL Server Management Studio 2008?

How to edit one specific row/tuple in Server Management Studio 2008/2012/2014/2016

Step 1: Right button mouse > Select "Edit Top 200 Rows"

Edit top 200 rows

Step 2: Navigate to Query Designer > Pane > SQL (Shortcut: Ctrl+3)

Navigate to Query Designer > Pane > SQL

Step 3: Modify the query

Modify the query

Step 4: Right button mouse > Select "Execute SQL" (Shortcut: Ctrl+R)

enter image description here

How to write dynamic variable in Ansible playbook

my_var: the variable declared

VAR: the variable, whose value is to be checked

param_1, param_2: values of the variable VAR

value_1, value_2, value_3: the values to be assigned to my_var according to the values of my_var

my_var: "{{ 'value_1' if VAR == 'param_1' else 'value_2' if VAR == 'param_2' else 'value_3' }}"

Powershell: How can I stop errors from being displayed in a script?

Windows PowerShell provides two mechanisms for reporting errors: one mechanism for terminating errors and another mechanism for non-terminating errors.

Internal CmdLets code can call a ThrowTerminatingError method when an error occurs that does not or should not allow the cmdlet to continue to process its input objects. The script writter can them use exception to catch these error.

EX :

  Your database code
  Error reporting/logging

Internal CmdLets code can call a WriteError method to report non-terminating errors when the cmdlet can continue processing the input objects. The script writer can then use -ErrorAction option to hide the messages, or use the $ErrorActionPreference to setup the entire script behaviour.

How do I disable a Pylint warning?

Edit "C:\Users\Your User\AppData\Roaming\Code\User\settings.json" and add 'python.linting.pylintArgs' with its lines at the end as shown below:

    "team.showWelcomeMessage": false,
    "python.dataScience.sendSelectionToInteractiveWindow": true,
    "git.enableSmartCommit": true,
    "powershell.codeFormatting.useCorrectCasing": true,
    "files.autoSave": "onWindowChange",
    "python.linting.pylintArgs": [

HTML-Tooltip position relative to mouse pointer

This CAN be done with pure html and css. It may not be the best way but we all have different limitations. There are 3 ways that could be useful depending on what your specific circumstances are.

  1. The first involves overlaying an invisible table over top of your link with a hover action on each cell that displays an image.

#imagehover td:hover::after{_x000D_
  content: "             ";_x000D_
  white-space: pre;_x000D_
  background-image: url("");_x000D_
  position: relative;_x000D_
  left: 5px;_x000D_
  top: 5px;_x000D_
  font-size: 20px;_x000D_
  background-color: transparent;_x000D_
  background-position: 0px 0px;_x000D_
  background-size: 60px 20px;_x000D_
  background-repeat: no-repeat;_x000D_
#imagehover table, #imagehover th, #imagehover td {_x000D_
  border: 0px;_x000D_
  border-spacing: 0px;_x000D_
<a href="">_x000D_
<table id="imagehover" style="width:50px;height:10px;z-index:9999;position:absolute" cellspacing="0">_x000D_

  1. The second relies on being able to create your own cursor image

cursor: url(,url(,auto;_x000D_
<a href="" id="googleLink">Google</a>

  1. While the normal title tooltip doesn't technically allow images it does allow any unicode characters including block letters and emojis which may suite your needs.

<a href="" title="??" alt="??">Google</a>

HTML code for an apostrophe

Although the &apos; entity may be supported in HTML5, it looks like a typewriter apostrophe. It looks nothing like a real curly apostrophe—which looks identical to an ending quotation mark: .

Just look when I write them after each other:

1: right single quotation mark entity, 2: apostrophe entity: '.

I tried to find a proper entity or alt command specifically for a normal looking apostrophe (which again, looks ‘identical’ to a closing right single quotation mark), but I haven’t found one. I always need to insert a right single quotation mark in order to get the visually correct apostrophe.

If you use just (ALT + 0146) or autoformat typewriter apostrophes and quotation marks as curly in a word processor like Word 2013, do use <meta charset="UTF-8">.

Navigation Drawer (Google+ vs. YouTube)

Just recently I forked a current Github project called "RibbonMenu" and edited it to fit my needs:

What's the Purpose

  • Ease of Access: Allow easy access to a menu that slides in and out
  • Ease of Implementation: Update the same screen using minimal amount of code
  • Independency: Does not require support libraries such as ActionBarSherlock
  • Customization: Easy to change colors and menus

What's New

  • Changed the sliding animation to match Facebook and Google+ apps
  • Added standard ActionBar (you can chose to use ActionBarSherlock)
  • Used menuitem to open the Menu
  • Added ability to update ListView on main Activity
  • Added 2 ListViews to the Menu, similiar to Facebook and Google+ apps
  • Added a AutoCompleteTextView and a Button as well to show examples of implemenation
  • Added method to allow users to hit the 'back button' to hide the menu when it is open
  • Allows users to interact with background(main ListView) and the menu at the same time unlike the Facebook and Google+ apps!

ActionBar with Menu out

ActionBar with Menu out

ActionBar with Menu out and search selected

ActionBar with Menu out and search selected

how to concat two columns into one with the existing column name in mysql?

As aziz-shaikh has pointed out, there is no way to suppress an individual column from the * directive, however you might be able to use the following hack:

FROM   `customer` c;

Doing this will cause the second occurrence of the FIRSTNAME column to adopt the alias FIRSTNAME_1 so you should be able to safely address your customised FIRSTNAME column. You need to alias the table because * in any position other than at the start will fail if not aliased.

Hope that helps!

PermGen elimination in JDK 8

Reasons of ignoring these argument is permanent generation has been removed in HotSpot for JDK8 because of following drawbacks

  • Fixed size at startup – difficult to tune.
  • Internal Hotspot types were Java objects : Could move with full GC, opaque, not strongly typed and hard to debug, needed meta-metadata.
  • Simplify full collections : Special iterators for metadata for each collector
  • Want to deallocate class data concurrently and not during GC pause
  • Enable future improvements that were limited by PermGen.

The Permanent Generation (PermGen) space has completely been removed and is kind of replaced by a new space called Metaspace. The consequences of the PermGen removal is that obviously the PermSize and MaxPermSize JVM arguments are ignored and you will never get a java.lang.OutOfMemoryError: PermGen error.

Advantages of MetaSpace

  • Take advantage of Java Language Specification property : Classes and associated metadata lifetimes match class loader’s
  • Per loader storage area – Metaspace
  • Linear allocation only
  • No individual reclamation (except for RedefineClasses and class loading failure)
  • No GC scan or compaction
  • No relocation for metaspace objects

Metaspace Tuning

The maximum metaspace size can be set using the -XX:MaxMetaspaceSize flag, and the default is unlimited, which means that only your system memory is the limit. The -XX:MetaspaceSize tuning flag defines the initial size of metaspace If you don’t specify this flag, the Metaspace will dynamically re-size depending of the application demand at runtime.

Change enables other optimizations and features in the future

  • Application class data sharing
  • Young collection optimizations, G1 class unloading
  • Metadata size reductions and internal JVM footprint projects

There is improved GC performace also.

Byte[] to ASCII

Encoding.GetString Method (Byte[]) convert bytes to a string.

When overridden in a derived class, decodes all the bytes in the specified byte array into a string.

Namespace: System.Text
Assembly: mscorlib (in mscorlib.dll)


public virtual string GetString(byte[] bytes)


    Type: System.Byte[]
    The byte array containing the sequence of bytes to decode.

Return Value

Type: System.String
A String containing the results of decoding the specified sequence of bytes.


ArgumentException        - The byte array contains invalid Unicode code points.
ArgumentNullException    - bytes is null.
DecoderFallbackException - A fallback occurred (see Character Encoding in the .NET Framework for complete explanation) or DecoderFallback is set to DecoderExceptionFallback.


If the data to be converted is available only in sequential blocks (such as data read from a stream) or if the amount of data is so large that it needs to be divided into smaller blocks, the application should use the Decoder or the Encoder provided by the GetDecoder method or the GetEncoder method, respectively, of a derived class.

See the Remarks under Encoding.GetChars for more discussion of decoding techniques and considerations.

How do I modify the URL without reloading the page?

Here is my solution (newUrl is your new URL which you want to replace with the current one):

history.pushState({}, null, newUrl);

How to delete duplicates on a MySQL table?

This always seems to work for me:

CREATE TABLE NoDupeTable LIKE DupeTable; 
INSERT NoDupeTable SELECT * FROM DupeTable group by CommonField1,CommonFieldN;

Which keeps the lowest ID on each of the dupes and the rest of the non-dupe records.

I've also taken to doing the following so that the dupe issue no longer occurs after the removal:

CREATE TABLE NoDupeTable LIKE DupeTable; 
Alter table NoDupeTable Add Unique `Unique` (CommonField1,CommonField2);

In other words, I create a duplicate of the first table, add a unique index on the fields I don't want duplicates of, and then do an Insert IGNORE which has the advantage of not failing as a normal Insert would the first time it tried to add a duplicate record based on the two fields and rather ignores any such records.

Moving fwd it becomes impossible to create any duplicate records based on those two fields.

Get the index of the object inside an array, matching a condition

Try this code

var x = [{prop1:"abc",prop2:"qwe"},{prop1:"bnmb",prop2:"yutu"},{prop1:"zxvz",prop2:"qwrq"}]
let index = x.findIndex(x => x.prop1 === 'zxvz')

How to convert ‘false’ to 0 and ‘true’ to 1 in Python

Here's a yet another solution to your problem:

def to_bool(s):
    return 1 - sum(map(ord, s)) % 2
    # return 1 - sum(s.encode('ascii')) % 2  # Alternative for Python 3

It works because the sum of the ASCII codes of 'true' is 448, which is even, while the sum of the ASCII codes of 'false' is 523 which is odd.

The funny thing about this solution is that its result is pretty random if the input is not one of 'true' or 'false'. Half of the time it will return 0, and the other half 1. The variant using encode will raise an encoding error if the input is not ASCII (thus increasing the undefined-ness of the behaviour).

Seriously, I believe the most readable, and faster, solution is to use an if:

def to_bool(s):
    return 1 if s == 'true' else 0

See some microbenchmarks:

In [14]: def most_readable(s):
    ...:     return 1 if s == 'true' else 0

In [15]: def int_cast(s):
    ...:     return int(s == 'true')

In [16]: def str2bool(s):
    ...:     try:
    ...:         return ['false', 'true'].index(s)
    ...:     except (ValueError, AttributeError):
    ...:         raise ValueError()

In [17]: def str2bool2(s):
    ...:     try:
    ...:         return ('false', 'true').index(s)
    ...:     except (ValueError, AttributeError):
    ...:         raise ValueError()

In [18]: def to_bool(s):
    ...:     return 1 - sum(s.encode('ascii')) % 2

In [19]: %timeit most_readable('true')
10000000 loops, best of 3: 112 ns per loop

In [20]: %timeit most_readable('false')
10000000 loops, best of 3: 109 ns per loop

In [21]: %timeit int_cast('true')
1000000 loops, best of 3: 259 ns per loop

In [22]: %timeit int_cast('false')
1000000 loops, best of 3: 262 ns per loop

In [23]: %timeit str2bool('true')
1000000 loops, best of 3: 343 ns per loop

In [24]: %timeit str2bool('false')
1000000 loops, best of 3: 325 ns per loop

In [25]: %timeit str2bool2('true')
1000000 loops, best of 3: 295 ns per loop

In [26]: %timeit str2bool2('false')
1000000 loops, best of 3: 277 ns per loop

In [27]: %timeit to_bool('true')
1000000 loops, best of 3: 607 ns per loop

In [28]: %timeit to_bool('false')
1000000 loops, best of 3: 612 ns per loop

Notice how the if solution is at least 2.5x times faster than all the other solutions. It does not make sense to put as a requirement to avoid using ifs except if this is some kind of homework (in which case you shouldn't have asked this in the first place).

How to read data from a file in Lua

Just a little addition if one wants to parse a space separated text file line by line.

read_file = function (path)
local file =, "rb") 
if not file then return nil end

local lines = {}

for line in io.lines(path) do
    local words = {}
    for word in line:gmatch("%w+") do 
        table.insert(words, word) 
  table.insert(lines, words)

return lines;

Why is my CSS style not being applied?

In addition to the solutions posted above, having gone through the exact same problem, make sure you check your HTML. More specifically whether you've properly labelled your elements, as well as class and id selectors. You can do this either manually or through a validator (

For me, I missed the equal sign next to the class (<div class someDiv> vs <div class = "someDiv">, hence why no CSS property was applied.

php static function

Simply, static functions function independently of the class where they belong.

$this means, this is an object of this class. It does not apply to static functions.

class test {
    public function sayHi($hi = "Hi") {
        $this->hi = $hi;
        return $this->hi;
class test1 {
    public static function sayHi($hi) {
        $hi = "Hi";
        return $hi;

//  Test
$mytest = new test();
print $mytest->sayHi('hello');  // returns 'hello'
print test1::sayHi('hello');    //  returns 'Hi'

How to retrieve Request Payload

If I understand the situation correctly, you are just passing json data through the http body, instead of application/x-www-form-urlencoded data.

You can fetch this data with this snippet:

$request_body = file_get_contents('php://input');

If you are passing json, then you can do:

$data = json_decode($request_body);

$data then contains the json data is php array.

php://input is a so called wrapper.

php://input is a read-only stream that allows you to read raw data from the request body. In the case of POST requests, it is preferable to use php://input instead of $HTTP_RAW_POST_DATA as it does not depend on special php.ini directives. Moreover, for those cases where $HTTP_RAW_POST_DATA is not populated by default, it is a potentially less memory intensive alternative to activating always_populate_raw_post_data. php://input is not available with enctype="multipart/form-data".

Could not find default endpoint element

The namespace in your config should reflect the rest of the namespace path after your client's default namespace (as configured in the project properties). Based on your posted answer, my guess is that your client is configured to be in the "Fusion.DataExchange.Workflows" namespace. If you moved the client code to another namespace you would need to update the config to match the remaining namespace path.

Put byte array to JSON and vice versa

Amazingly now org.json now lets you put a byte[] object directly into a json and it remains readable. you can even send the resulting object over a websocket and it will be readable on the other side. but i am not sure yet if the size of the resulting object is bigger or smaller than if you were converting your byte array to base64, it would certainly be neat if it was smaller.

It seems to be incredibly hard to measure how much space such a json object takes up in java. if your json consists merely of strings it is easily achievable by simply stringifying it but with a bytearray inside it i fear it is not as straightforward.

stringifying our json in java replaces my bytearray for a 10 character string that looks like an id. doing the same in node.js replaces our byte[] for an unquoted value reading <Buffered Array: f0 ff ff ...> the length of the latter indicates a size increase of ~300% as would be expected

Git: copy all files in a directory from another branch

If there are no spaces in paths, and you are interested, like I was, in files of specific extension only, you can use

git checkout otherBranch -- $(git ls-tree --name-only -r otherBranch | egrep '*.java')

keycode and charcode

Okay, here are the explanations.

e.keyCode - used to get the number that represents the key on the keyboard

e.charCode - a number that represents the unicode character of the key on keyboard

e.which - (jQuery specific) is a property introduced in jQuery (DO Not use in plain javascript)

Below is the code snippet to get the keyCode and charCode

// get key code
function getKey(event) {
  event = event || window.event;
  var keyCode = event.which || event.keyCode;

// get char code
function getChar(event) {
  event = event || window.event;
  var keyCode = event.which || event.keyCode;
  var typedChar = String.fromCharCode(keyCode);

Live example of Getting keyCode and charCode in JavaScript.

Set up Python 3 build system with Sublime Text 3

If you are using PyQt, then for normal work, you should add "shell":"true" value, this looks like:

  "cmd": ["c:/Python32/python.exe", "-u", "$file"],
  "file_regex": "^[ ]*File \"(...*?)\", line ([0-9]*)",
  "selector": "source.python",

The shortest possible output from git log containing author and date

git --no-pager log --pretty=tformat:"%C(yellow)%h %C(cyan)%ad %Cblue%an%C(auto)%d %Creset%s" --graph --date=format:"%Y-%m-%d %H:%M" -25 

I use alias

alias gitlog='git --no-pager log --pretty=tformat:"%C(yellow)%h %C(cyan)%ad %Cblue%an%C(auto)%d %Creset%s" --graph --date=format:"%Y-%m-%d %H:%M" -25'

Differences: I use tformat and isodate without seconds and time zones , with --no-pager you will see colors

Calling another different view from the controller using ASP.NET MVC 4

Also, you can just set the ViewName:

return View("ViewName");

Full controller example:

public ActionResult SomeAction() {
    if (condition)
        return View("CustomView");
        return View();

This works on MVC 5.

Is there an exponent operator in C#?

Since no-one has yet wrote a function to do this with two integers, here's one way:

private long CalculatePower(int number, int powerOf)
    for (int i = powerOf; i > 1; i--)
        number *= number;
    return number;
CalculatePower(5, 3); // 125
CalculatePower(8, 4); // 4096
CalculatePower(6, 2); // 36

Alternatively in VB.NET:

Private Function CalculatePower(number As Integer, powerOf As Integer) As Long
    For i As Integer = powerOf To 2 Step -1
        number *= number
    Return number
End Function
CalculatePower(5, 3) ' 125
CalculatePower(8, 4) ' 4096
CalculatePower(6, 2) ' 36

mongodb: insert if not exists

Sounds like you want to do an "upsert". MongoDB has built-in support for this. Pass an extra parameter to your update() call: {upsert:true}. For example:

key = {'key':'value'}
data = {'key2':'value2', 'key3':'value3'};
coll.update(key, data, upsert=True); #In python upsert must be passed as a keyword argument

This replaces your if-find-else-update block entirely. It will insert if the key doesn't exist and will update if it does.


{"key":"value", "key2":"Ohai."}


{"key":"value", "key2":"value2", "key3":"value3"}

You can also specify what data you want to write:

data = {"$set":{"key2":"value2"}}

Now your selected document will update the value of "key2" only and leave everything else untouched.

"SetPropertiesRule" warning message when starting Tomcat from Eclipse

I had the same problem with Eclipse 3.4(Ganymede) and dynamic web project.
The message didn't influence successfull deploy.But I had to delete row

<wb-resource deploy-path="/WEB-INF/classes" source-path="/src/main/resources"/>

from org.eclipse.wst.common.component file in .settings folder of Eclipse

ConcurrentHashMap vs Synchronized HashMap

SynchronizedMap and ConcurrentHashMap are both thread safe class and can be used in multithreaded application, the main difference between them is regarding how they achieve thread safety.

SynchronizedMap acquires lock on the entire Map instance , while ConcurrentHashMap divides the Map instance into multiple segments and locking is done on those.

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Appending a vector to a vector

If you would like to add vector to itself both popular solutions will fail:

std::vector<std::string> v, orig;


// BAD:
v = orig;
v.insert(v.end(), v.begin(), v.end());
// Now v contains: { "first", "second", "", "" }

// BAD:
v = orig;
std::copy(v.begin(), v.end(), std::back_inserter(v));
// std::bad_alloc exception is generated

// GOOD, but I can't guarantee it will work with any STL:
v = orig;
v.insert(v.end(), v.begin(), v.end());
// Now v contains: { "first", "second", "first", "second" }

// GOOD, but I can't guarantee it will work with any STL:
v = orig;
std::copy(v.begin(), v.end(), std::back_inserter(v));
// Now v contains: { "first", "second", "first", "second" }

// GOOD (best):
v = orig;
v.insert(v.end(), orig.begin(), orig.end()); // note: we use different vectors here
// Now v contains: { "first", "second", "first", "second" }

Calling a Javascript Function from Console

An example of where the console will return ReferenceError is putting a function inside a JQuery document ready function

//this will fail
$(document).ready(function () {
          myFunction(alert('doing something!'));
          //other stuff

To succeed move the function outside the document ready function

//this will work
myFunction(alert('doing something!'));
$(document).ready(function () {

          //other stuff

Then in the console window, type the function name with the '()' to execute the function


Also of use is being able to print out the function body to remind yourself what the function does. Do this by leaving off the '()' from the function name

function myFunction(alert('doing something!'))

Of course if you need the function to be registered after the document is loaded then you couldn't do this. But you might be able to work around that.

Abstract Class vs Interface in C++

Please don't put members into an interface; though it's correct in phrasing. Please don't "delete" an interface.

class IInterface() 
   Virtual ~IInterface(){}; 

Class ClassImpl : public IInterface 

Int main() 

  IInterface* pInterface = new ClassImpl(); 
  delete pInterface; // Wrong in OO Programming, correct in C++.

Alter Table Add Column Syntax

Just remove COLUMN from ADD COLUMN

  ADD EmployeeID numeric NOT NULL IDENTITY (1, 1)


Flutter- wrapping text

The Flexible does the trick

new Container(
       child: Row(
         children: <Widget>[
               child: new Text("A looooooooooooooooooong text"))

This is the official doc on how to arrange widgets.

Remember that Flexible and also Expanded, should only be used within a Column, Row or Flex, because of the Incorrect use of ParentDataWidget.

The solution is not the mere Flexible

How to pass command line argument to gnuplot?

The answer of Jari Laamanen is the best solution. I want just explain how to use more than 1 input parameter with shell variables:

gnuplot -e "datafile='${data}'; outputname='${output}'" foo.plg

and foo.plg:

set terminal png
set outputname 
f(x) = sin(x)
plot datafile

As you can see,more parameters are passed with semi colons (like in bash scripts), but string variables NEED to be encapsuled with ' ' (gnuplot syntax, NOT Bash syntax)

org.glassfish.jersey.servlet.ServletContainer ClassNotFoundException

Suppose you are usin Jersey 2.25.1, this worked for me - I am using Apache Tomcat web container:


NB: Replace version with the version you are using

pytest cannot import module while python can

This problem will happen if you have a file and a tests folder with tests/

During the collection pytest finds the folder, but when it tries to import the test files from the folder, file will cause the import problem.

To fix simply remove the file and put all your tests inside the tests/ folder.

For your specific case the fix will be precisely:

  • Remove the file /home/zz/Desktop/GitFolders/rc/
  • Make sure /home/zz/Desktop/GitFolders/rc/tests/ is present

No serializer found for class org.hibernate.proxy.pojo.javassist.Javassist?

It could be your Hibernate entity relationship causing the issue...simply stop lazy loading of that related entity...for example...I resolved below by setting lazy="false" for customerType.

<class name="Customer" table="CUSTOMER">
        <id name="custId" type="long">
            <column name="CUSTID" />
            <generator class="assigned" />
        <property name="name" type="java.lang.String">
            <column name="NAME" />
        <property name="phone" type="java.lang.String">
            <column name="PHONE" />
        <property name="pan" type="java.lang.String">
            <column name="PAN" />

        <many-to-one name="customerType" not-null="true" lazy="false"></many-to-one>

A message body writer for Java type, class myPackage.B, and MIME media type, application/octet-stream, was not found

This can also happen if you've recently upgraded Ant. I was using Ant 1.8.4 on a project, and upgraded Ant to 1.9.4, and started to get this error when building a fat jar using Ant.

The solution for me was to downgrade back to Ant 1.8.4 for the command line and Eclipse using the process detailed here

installation app blocked by play protect

Try to create a new key store and replace with old one, then rebuild a new signed APK.

Update: Note that if you're using a http connection with server ,you should use SSL.

Take a look at:

How to comment out particular lines in a shell script

for single line comment add # at starting of a line
for multiple line comments add ' (single quote) from where you want to start & add ' (again single quote) at the point where you want to end the comment line.

moment.js - UTC gives wrong date

By default, MomentJS parses in local time. If only a date string (with no time) is provided, the time defaults to midnight.

In your code, you create a local date and then convert it to the UTC timezone (in fact, it makes the moment instance switch to UTC mode), so when it is formatted, it is shifted (depending on your local time) forward or backwards.

If the local timezone is UTC+N (N being a positive number), and you parse a date-only string, you will get the previous date.

Here are some examples to illustrate it (my local time offset is UTC+3 during DST):

>>> moment('07-18-2013', 'MM-DD-YYYY').utc().format("YYYY-MM-DD HH:mm")
"2013-07-17 21:00"
>>> moment('07-18-2013 12:00', 'MM-DD-YYYY HH:mm').utc().format("YYYY-MM-DD HH:mm")
"2013-07-18 09:00"
>>> Date()
"Thu Jul 25 2013 14:28:45 GMT+0300 (Jerusalem Daylight Time)"

If you want the date-time string interpreted as UTC, you should be explicit about it:

>>> moment(new Date('07-18-2013 UTC')).utc().format("YYYY-MM-DD HH:mm")
"2013-07-18 00:00"

or, as Matt Johnson mentions in his answer, you can (and probably should) parse it as a UTC date in the first place using moment.utc() and include the format string as a second argument to prevent ambiguity.

>>> moment.utc('07-18-2013', 'MM-DD-YYYY').format("YYYY-MM-DD HH:mm")
"2013-07-18 00:00"

To go the other way around and convert a UTC date to a local date, you can use the local() method, as follows:

>>> moment.utc('07-18-2013', 'MM-DD-YYYY').local().format("YYYY-MM-DD HH:mm")
"2013-07-18 03:00"

Get domain name from given url

private static final String hostExtractorRegexString = "(?:https?://)?(?:www\\.)?(.+\\.)(com|au\\.uk|co\\.in|be|in|uk|org\\.in|org|net|edu|gov|mil)";
private static final Pattern hostExtractorRegexPattern = Pattern.compile(hostExtractorRegexString);

public static String getDomainName(String url){
    if (url == null) return null;
    url = url.trim();
    Matcher m = hostExtractorRegexPattern.matcher(url);
    if(m.find() && m.groupCount() == 2) {
        return +;
    return null;

Explanation : The regex has 4 groups. The first two are non-matching groups and the next two are matching groups.

The first non-matching group is "http" or "https" or ""

The second non-matching group is "www." or ""

The second matching group is the top level domain

The first matching group is anything after the non-matching groups and anything before the top level domain

The concatenation of the two matching groups will give us the domain/host name.

PS : Note that you can add any number of supported domains to the regex.

How do I sleep for a millisecond in Perl?

From the Perldoc page on sleep:

For delays of finer granularity than one second, the Time::HiRes module (from CPAN, and starting from Perl 5.8 part of the standard distribution) provides usleep().

Actually, it provides usleep() (which sleeps in microseconds) and nanosleep() (which sleeps in nanoseconds). You may want usleep(), which should let you deal with easier numbers. 1 millisecond sleep (using each):

use strict;
use warnings;

use Time::HiRes qw(usleep nanosleep);

# 1 millisecond == 1000 microseconds
# 1 microsecond == 1000 nanoseconds

If you don't want to (or can't) load a module to do this, you may also be able to use the built-in select() function:

# Sleep for 250 milliseconds
select(undef, undef, undef, 0.25);

Creating NSData from NSString in Swift

Here very simple method

let data = string.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)

setInterval in a React app

If anyone is looking for a React Hook approach to implementing setInterval. Dan Abramov talked about it on his blog. Check it out if you want a good read about the subject including a Class approach. Basically the code is a custom Hook that turns setInterval as declarative.

function useInterval(callback, delay) {
  const savedCallback = useRef();

  // Remember the latest callback.
  useEffect(() => {
    savedCallback.current = callback;
  }, [callback]);

  // Set up the interval.
  useEffect(() => {
    function tick() {
    if (delay !== null) {
      let id = setInterval(tick, delay);
      return () => clearInterval(id);
  }, [delay]);

Also posting the CodeSandbox link for convenience:

Excel VBA For Each Worksheet Loop

Try this more succinct code:

Sub LoopOverEachColumn()
    Dim WS As Worksheet
    For Each WS In ThisWorkbook.Worksheets
        ResizeColumns WS
    Next WS
End Sub

Private Sub ResizeColumns(WS As Worksheet)
    Dim StrSize As String
    Dim ColIter As Long
    StrSize = "20.14;9.71;35.86;30.57;23.57;21.43;18.43;23.86;27.43;36.71;30.29;31.14;31;41.14;33.86"
    For ColIter = 1 To 15
        WS.Columns(ColIter).ColumnWidth = Split(StrSize, ";")(ColIter - 1)
    Next ColIter
End Sub

If you want additional columns, just change 1 to 15 to 1 to X where X is the column index of the column you want, and append the column size you want to StrSize.

For example, if you want P:P to have a width of 25, just add ;25 to StrSize and change ColIter... to ColIter = 1 to 16.

Hope this helps.

Get all rows from SQLite

Update queueAll() method as below:

public Cursor queueAll() {

     String selectQuery = "SELECT * FROM " + MYDATABASE_TABLE;
     Cursor cursor = sqLiteDatabase.rawQuery(selectQuery, null);

     return cursor;

Update readFileFromSQLite() method as below:

public ArrayList<String> readFileFromSQLite() {

    fileName = new ArrayList<String>();

    fileSQLiteAdapter = new FileSQLiteAdapter(FileChooser.this);

    cursor = fileSQLiteAdapter.queueAll();

    if (cursor != null) {
        if (cursor.moveToFirst()) {
                String name = cursor.getString(cursor.getColumnIndex(FileSQLiteAdapter.KEY_CONTENT1));
            } while (cursor.moveToNext());


    return fileName;

no operator "<<" matches these operands

It looks like you're comparing strings incorrectly. To compare a string to another, use the std::string::compare function.


     while ((wrong < MAX_WRONG) && ( != 0)) 

Group by multiple field names in java 8

Here look at the code:

You can simply create a Function and let it do the work for you, kind of functional Style!

Function<Person, List<Object>> compositeKey = personRecord ->
    Arrays.<Object>asList(personRecord.getName(), personRecord.getAge());

Now you can use it as a map:

Map<Object, List<Person>> map =
people.collect(Collectors.groupingBy(compositeKey, Collectors.toList()));


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

What's wrong with this 1 simple line?

new LocalDateTime(new Date().getTime()).toLocalDate();

In MVC, how do I return a string result?

You can also just return string if you know that's the only thing the method will ever return. For example:

public string MyActionName() {
  return "Hi there!";

CSS Positioning Elements Next to each other

If you want them to be displayed side by side, why is sideContent the child of mainContent? make them siblings then use:

float:left; display:inline; width: 49%;

on both of them.

#mainContent, #sideContent {float:left; display:inline; width: 49%;}

NPM Install Error:Unexpected end of JSON input while parsing near '...nt-webpack-plugin":"0'

If npm cache clean --force doesn't resolve the issue, try deleting the ~/.npm directory (*nix/macOS). This is the directory where node stores its cache, locks, logs, global packages (unless you're using nvm), and modules installed via npx.

First, backup your current ~./npm directory:

mv ~/.npm ~/.npm-backup

Now try running your npm command again. This will create a new ~/.npm directory. If the issue is resolved, you can safely remove you backup. Before doing so, you may want to review the global packages installed in your ~/.npm-backup directory so you can reinstall them using npm i -g [package].

rm -rf ~/.npm-backup

If the issue is not resolved, you can restore your backup:

rm -rf ~/.npm
mv ~/.npm-backup ~/.npm

Careful with those rm commands, folks!

How to delete session cookie in Postman?

Is the Postman Interceptor enabled? Toggling it will route all requests and responses through the Chrome browser.

Interceptor - Cookies documentation -

Center content vertically on Vuetify

For me, align="center" was enough to center FOO vertically:

<v-row align="center">

How do I get the computer name in .NET

Try this one.

public static string GetFQDN()
    string domainName = NetworkInformation.IPGlobalProperties.GetIPGlobalProperties().DomainName;
    string hostName = Dns.GetHostName();
    string fqdn;
    if (!hostName.Contains(domainName))
        fqdn = hostName + "." +domainName;
        fqdn = hostName;

    return fqdn;

How to upgrade PowerShell version from 2.0 to 3.0

  1. Install Chocolatey
  2. Run the following commands in CMD

    • choco install powershell

    • choco upgrade powershell

How do I access the HTTP request header fields via JavaScript?

Almost by definition, the client-side JavaScript is not at the receiving end of a http request, so it has no headers to read. Most commonly, your JavaScript is the result of an http response. If you are trying to get the values of the http request that generated your response, you'll have to write server side code to embed those values in the JavaScript you produce.

It gets a little tricky to have server-side code generate client side code, so be sure that is what you need. For instance, if you want the User-agent information, you might find it sufficient to get the various values that JavaScript provides for browser detection. Start with navigator.appName and navigator.appVersion.

How do I find a list of Homebrew's installable packages?

From the man page:

search, -S text|/text/
Perform a substring search of formula names for text. If text is surrounded with slashes,
then it is interpreted as a regular expression. If no search term is given,
all available formula are displayed.

For your purposes, brew search will suffice.

ASP.NET MVC5/IIS Express unable to debug - Code Not Running

Another scenario may be that the port that IIS is using for your application is already being used by another running application. Try changing the port and see if it works for you.

How to compare two dates?

Other answers using datetime and comparisons also work for time only, without a date.

For example, to check if right now it is more or less than 8:00 a.m., we can use:

import datetime

eight_am = datetime.time( 8,0,0 ) # Time, without a date

And later compare with: > eight_am  

which will return True

Configuring angularjs with eclipse IDE

Now you can see the Angularjs tags available as shown below.

AngularJS Tags are available.

How can I add to a List's first position?

Use List.Insert(0, ...). But are you sure a LinkedList isn't a better fit? Each time you insert an item into an array at a position other than the array end, all existing items will have to be copied to make space for the new one.

raw vs. html_safe vs. h to unescape html

The difference is between Rails’ html_safe() and raw(). There is an excellent post by Yehuda Katz on this, and it really boils down to this:

def raw(stringish)



Yes, raw() is a wrapper around html_safe() that forces the input to String and then calls html_safe() on it. It’s also the case that raw() is a helper in a module whereas html_safe() is a method on the String class which makes a new ActiveSupport::SafeBuffer instance — that has a @dirty flag in it.

Refer to "Rails’ html_safe vs. raw".

How do I find all files containing specific text on Linux?

grep can be used even if we're not looking for a string.

Simply running,

grep -RIl "" .

will print out the path to all text files, i.e. those containing only printable characters.

Remove ListView items in Android

It's simple .First you should clear your collection and after clear list like this code :


How to get the index of an element in an IEnumerable?

I think the best option is to implement like this:

public static int IndexOf<T>(this IEnumerable<T> enumerable, T element, IEqualityComparer<T> comparer = null)
    int i = 0;
    comparer = comparer ?? EqualityComparer<T>.Default;
    foreach (var currentElement in enumerable)
        if (comparer.Equals(currentElement, element))
            return i;


    return -1;

It will also not create the anonymous object

TypeScript-'s Angular Framework Error - "There is no directive with exportAs set to ngForm"

I just moved routing modules i.e. say ARoutingModule above FormsModule and ReactiveFormsModule and after CommonModule in imports array of modules.

Mixing C# & VB In The Same Project

I don't see how you can compile a project with the C# compiler (or the VB compiler) and not have it balk at the wrong language for the compiler.

Keep your C# code in a separate project from your VB project. You can include these projects into the same solution.

How to ssh from within a bash script?

What you need to do is to exchange the SSH keys for the user the script runs as. Have a look at this tutorial

After doing so, your scripts will run without the need for entering a password. But, for security's sake, you don't want to do this for root users!

How can I open Windows Explorer to a certain directory from within a WPF app?

This should work:

Process.Start(@"<directory goes here>")

Or if you'd like a method to run programs/open files and/or folders:

private void StartProcess(string path)
    ProcessStartInfo StartInformation = new ProcessStartInfo();

    StartInformation.FileName = path;

    Process process = Process.Start(StartInformation);

    process.EnableRaisingEvents = true;

And then call the method and in the parenthesis put either the directory of the file and/or folder there or the name of the application. Hope this helped!

Static vs class functions/variables in Swift classes?

static and class both associate a method with a class, rather than an instance of a class. The difference is that subclasses can override class methods; they cannot override static methods.

class properties will theoretically function in the same way (subclasses can override them), but they're not possible in Swift yet.

Use the auto keyword in C++ STL

The auto keyword is simply asking the compiler to deduce the type of the variable from the initialization.

Even a pre-C++0x compiler knows what the type of an (initialization) expression is, and more often than not, you can see that type in error messages.

#include <vector>
#include <iostream>
using namespace std;

int main()
    for (int it=s.begin();it!=s.end();it++){

Line 12: error: cannot convert '__gnu_debug::_Safe_iterator<__gnu_cxx::__normal_iterator<int*, __gnu_norm::vector<int, std::allocator<int> > >, __gnu_debug_def::vector<int, std::allocator<int> > >' to 'int' in initialization

The auto keyword simply allows you to take advantage of this knowledge - if you (compiler) know the right type, just choose for me!

Angular 2 ngfor first, last, index loop

Here is how its done in Angular 6

<li *ngFor="let user of userObservable ; first as isFirst">
   <span *ngIf="isFirst">default</span>

Note the change from let first = first to first as isFirst

In log4j, does checking isDebugEnabled before logging improve performance?

Option 2 is better.

Per se it does not improve performance. But it ensures performance does not degrade. Here's how.

Normally we expect logger.debug(someString);

But usually, as the application grows, changes many hands, esp novice developers, you could see

logger.debug(str1 + str2 + str3 + str4);

and the like.

Even if log level is set to ERROR or FATAL, the concatenation of strings do happen ! If the application contains lots of DEBUG level messages with string concatenations, then it certainly takes a performance hit especially with jdk 1.4 or below. (Iam not sure if later versions of jdk internall do any stringbuffer.append()).

Thats why Option 2 is safe. Even the string concatenations dont happen.

Assigning a variable NaN in python without numpy

You can get NaN from "inf - inf", and you can get "inf" from a number greater than 2e308, so, I generally used:

>>> inf = 9e999
>>> inf
>>> inf - inf

How to check the extension of a filename in a bash script?


if [ "$file" == "*.txt" ]

like this:

if [[ $file == *.txt ]]

That is, double brackets and no quotes.

The right side of == is a shell pattern. If you need a regular expression, use =~ then.

Datetime current year and month in Python

Late answer, but you can also use:

import time
ym = time.strftime("%Y-%m")

What are Maven goals and phases and what is their difference?

The chosen answer is great, but still I would like to add something small to the topic. An illustration.

It clearly demonstrates how the different phases binded to different plugins and the goals that those plugins expose.

So, let's examine a case of running something like mvn compile:

  • It's a phase which execute the compiler plugin with compile goal
  • Compiler plugin got different goals. For mvn compile it's mapped to a specific goal, the compile goal.
  • It's the same as running mvn compiler:compile

Therefore, phase is made up of plugin goals.

enter image description here

Link to the reference

While, Do While, For loops in Assembly Language (emu8086)


For-loop in C:

for(int x = 0; x<=3; x++)
    //Do something!

The same loop in 8086 assembler:

        xor cx,cx   ; cx-register is the counter, set to 0
loop1   nop         ; Whatever you wanna do goes here, should not change cx
        inc cx      ; Increment
        cmp cx,3    ; Compare cx to the limit
        jle loop1   ; Loop while less or equal

That is the loop if you need to access your index (cx). If you just wanna to something 0-3=4 times but you do not need the index, this would be easier:

        mov cx,4    ; 4 iterations
loop1   nop         ; Whatever you wanna do goes here, should not change cx
        loop loop1  ; loop instruction decrements cx and jumps to label if not 0

If you just want to perform a very simple instruction a constant amount of times, you could also use an assembler-directive which will just hardcore that instruction

times 4 nop


Do-while-loop in C:

int x=1;
    //Do something!

The same loop in assembler:

        mov ax,1
loop1   nop         ; Whatever you wanna do goes here
        cmp ax,1    ; Check wether cx is 1
        je loop1    ; And loop if equal


While-loop in C:

    //Do something

The same loop in assembler:

        jmp loop1   ; Jump to condition first
cloop1  nop         ; Execute the content of the loop
loop1   cmp ax,1    ; Check the condition
        je cloop1   ; Jump to content of the loop if met

For the for-loops you should take the cx-register because it is pretty much standard. For the other loop conditions you can take a register of your liking. Of course replace the no-operation instruction with all the instructions you wanna perform in the loop.

Batch script to find and replace a string in text file within a minute for files up to 12 MB

Try this:

@echo off &setlocal
setlocal enabledelayedexpansion

set "search=%1"
set "replace=%2"
set "textfile=Input.txt"
set "newfile=Output.txt"
(for /f "delims=" %%i in (%textfile%) do (
    set "line=%%i"
    set "line=!line:%search%=%replace%!"
del %textfile%
rename %newfile%  %textfile%

UITableViewCell, show delete button on swipe

Swift 2.2 :

override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
    return true

override func tableView(tableView: UITableView,
    editActionsForRowAtIndexPath indexPath: NSIndexPath) -> [UITableViewRowAction]? {
    let delete = UITableViewRowAction(style: UITableViewRowActionStyle.Default, title: "DELETE"){(UITableViewRowAction,NSIndexPath) -> Void in

    print("Your action when user pressed delete")
let edit = UITableViewRowAction(style: UITableViewRowActionStyle.Normal, title: "EDIT"){(UITableViewRowAction,NSIndexPath) -> Void in

    print("Your action when user pressed edit")
    return [delete, block]

Getting output of system() calls in Ruby

Just for the record, if you want both (output and operation result) you can do:

output=`ls no_existing_file` ;  result=$?.success?

calling a java servlet from javascript

var button = document.getElementById("<<button-id>>");
button.addEventListener("click", function() {
  window.location.href= "<<full-servlet-path>>" (eg. http://localhost:8086/xyz/servlet)

Casting interfaces for deserialization in JSON.NET

@SamualDavis provided a great solution in a related question, which I'll summarize here.

If you have to deserialize a JSON stream into a concrete class that has interface properties, you can include the concrete classes as parameters to a constructor for the class! The NewtonSoft deserializer is smart enough to figure out that it needs to use those concrete classes to deserialize the properties.

Here is an example:

public class Visit : IVisit
    /// <summary>
    /// This constructor is required for the JSON deserializer to be able
    /// to identify concrete classes to use when deserializing the interface properties.
    /// </summary>
    public Visit(MyLocation location, Guest guest)
        Location = location;
        Guest = guest;
    public long VisitId { get; set; }
    public ILocation Location { get;  set; }
    public DateTime VisitDate { get; set; }
    public IGuest Guest { get; set; }

Warning: #1265 Data truncated for column 'pdd' at row 1

As the message error says, you need to Increase the length of your column to fit the length of the data you are trying to insert (0000-00-00)


Following your comment, I run a test table:

mysql> create table testDate(id int(2) not null auto_increment, pdd date default null, primary key(id));
Query OK, 0 rows affected (0.20 sec)


mysql> insert into testDate values(1,'0000-00-00');
Query OK, 1 row affected (0.06 sec)


So, aparently you want to insert a NULL value to pdd field as your comment states ? You can do that in 2 ways like this:

Method 1:

mysql> insert into testDate values(2,'');
Query OK, 1 row affected, 1 warning (0.06 sec)

Method 2:

mysql> insert into testDate values(3,NULL);
Query OK, 1 row affected (0.07 sec)


You failed to change the default value of pdd field. Here is the syntax how to do it (in my case, I set it to NULL in the start, now I will change it to NOT NULL)

mysql> alter table testDate modify pdd date not null;
Query OK, 3 rows affected, 1 warning (0.60 sec)
Records: 3  Duplicates: 0  Warnings: 1

What is for Python what 'explode' is for PHP?

Choose one you need:

>>> s = "Rajasekar SP  def"
>>> s.split(' ')
['Rajasekar', 'SP', '', 'def']
>>> s.split()
['Rajasekar', 'SP', 'def']
>>> s.partition(' ')
('Rajasekar', ' ', 'SP  def')

str.split and str.partition

if arguments is equal to this string, define a variable like this string

It seems that you are looking to parse commandline arguments into your bash script. I have searched for this recently myself. I came across the following which I think will assist you in parsing the arguments:

I added the snippet below as a tl;dr

#using : after a switch variable means it requires some input (ie, t: requires something after t to validate while h requires nothing.
while getopts “ht:r:p:v” OPTION
     case $OPTION in
             exit 1

if [[ -z $TEST ]] || [[ -z $SERVER ]] || [[ -z $PASSWD ]]
     exit 1

./ -t test -r server -p password -v

Multiple inputs on one line

Yes, you can input multiple items from cin, using exactly the syntax you describe. The result is essentially identical to:

cin >> a;
cin >> b;
cin >> c;

This is due to a technique called "operator chaining".

Each call to operator>>(istream&, T) (where T is some arbitrary type) returns a reference to its first argument. So cin >> a returns cin, which can be used as (cin>>a)>>b and so forth.

Note that each call to operator>>(istream&, T) first consumes all whitespace characters, then as many characters as is required to satisfy the input operation, up to (but not including) the first next whitespace character, invalid character, or EOF.

Rails: How to run `rails generate scaffold` when the model already exists?

I had this challenge when working on a Rails 6 API application in Ubuntu 20.04.

I had already existing models, and I needed to generate corresponding controllers for the models and also add their allowed attributes in the controller params.

Here's how I did it:

I used the rails generate scaffold_controller to get it done.

I simply ran the following commands:

rails generate scaffold_controller School name:string logo:json motto:text address:text

rails generate scaffold_controller Program name:string logo:json school:references

This generated the corresponding controllers for the models and also added their allowed attributes in the controller params, including the foreign key attributes.

create  app/controllers/schools_controller.rb
invoke  test_unit
create    test/controllers/schools_controller_test.rb

create  app/controllers/programs_controller.rb
invoke  test_unit
create    test/controllers/programs_controller_test.rb

That's all.

I hope this helps

How to correctly catch change/focusOut event on text input in React.js?

Its late, yet it's worth your time nothing that, there are some differences in browser level implementation of focusin and focusout events and react synthetic onFocus and onBlur. focusin and focusout actually bubble, while onFocus and onBlur dont. So there is no exact same implementation for focusin and focusout as of now for react. Anyway most cases will be covered in onFocus and onBlur.

How to change port for jenkins window service when 8080 is being used

On Windows (with Windows Service).

Edit the file C:\Program Files (x86)\Jenkins\jenkins.xml with 8083 if you want 8083 port.

<arguments>-Xrs -Xmx256m -Dhudson.lifecycle=hudson.lifecycle.WindowsServiceLifecycle -jar "%BASE%\jenkins.war" --httpPort=8083</arguments>

how to change text box value with jQuery?

You could just use this very simple way

  $(function() {

    $('#cd').click(function() {
      $('#dsf').val("any thing here");


How to do vlookup and fill down (like in Excel) in R?

I also like using qdapTools::lookup or shorthand binary operator %l%. It works identically to an Excel vlookup, but it accepts name arguments opposed to column numbers

## Replicate Ben's data:
hous <- structure(list(HouseType = c("Semi", "Single", "Row", "Single", 
    "Apartment", "Apartment", "Row"), HouseTypeNo = c(1L, 2L, 3L, 
    2L, 4L, 4L, 3L)), .Names = c("HouseType", "HouseTypeNo"), 
    class = "data.frame", row.names = c(NA, -7L))

largetable <- data.frame(HouseType = as.character(sample(unique(hous$HouseType), 
    1000, replace = TRUE)), stringsAsFactors = FALSE)

## It's this simple:
largetable[, 1] %l% hous

How to drop all user tables?

To remove all objects in oracle :

1) Dynamic



        union ALL
        select 'drop '||object_type||' '|| object_name || ';' from user_objects 
        where object_type in ('VIEW','PACKAGE','SEQUENCE', 'PROCEDURE', 'FUNCTION')
        union ALL
        SELECT 'drop '
        ||' '
        || object_name
        || ' force;'
        FROM user_objects
        WHERE object_type IN ('TYPE');

Angular - "has no exported member 'Observable'"

In my case this error was happening because I had an old version of ng cli in my computer.

The problem was solved after running:

ng update

ng update @angular/cli

Could not resolve Spring property placeholder

You may have more than one org.springframework.beans.factory.config.PropertyPlaceholderConfigurer in your application. Try setting a breakpoint on the setLocations method of the superclass and see if it's called more than once at application startup. If there is more than one org.springframework.beans.factory.config.PropertyPlaceholderConfigurer, you might need to look at configuring the ignoreUnresolvablePlaceholders property so that your application will start up cleanly.

What is the purpose of XSD files?

The xsd file is the schema of the xml file - it defines which elements may occur and their restrictions (like amount, order, boundaries, relationships,...)

add a temporary column with a value

select field1, field2, '' as newfield from table1

This Will Do you Job

How to end a session in ExpressJS


delete req.session.yoursessionname;

Node.js https pem error: routines:PEM_read_bio:no start line

If you log the

var options = {
  key: fs.readFileSync('./key.pem', 'utf8'),
  cert: fs.readFileSync('./csr.pem', 'utf8')

You might notice there are invalid characters due to improper encoding.

How to force a line break on a Javascript concatenated string?

You need to use \n inside quotes.

document.getElementById("address_box").value = (title + "\n" + address + "\n" + address2 + "\n" + address3 + "\n" + address4)

\n is called a EOL or line-break, \n is a common EOL marker and is commonly refereed to as LF or line-feed, it is a special ASCII character

If file exists then delete the file

You're close, you just need to delete the file before trying to over-write it.

dim infolder: set infolder = fso.GetFolder(IN_PATH)
dim file: for each file in infolder.Files

    dim name: name =
    dim parts: parts = split(name, ".")

    if UBound(parts) = 2 then

       ' file name like a.c.pdf    

        dim newname: newname = parts(0) & "." & parts(2)
        dim newpath: newpath = fso.BuildPath(OUT_PATH, newname)

        ' warning:
        ' if we have source files C:\IN_PATH\ABC.01.PDF, C:\IN_PATH\ABC.02.PDF, ...
        ' only one of them will be saved as D:\OUT_PATH\ABC.PDF

        if fso.FileExists(newpath) then
            fso.DeleteFile newpath
        end if

        file.Move newpath

    end if


Python 3 - ValueError: not enough values to unpack (expected 3, got 2)

You probably want to assign the lastname you are reading out here

lastname = sheet.cell(row=r, column=3).value

to something; currently the program just forgets it

you could do that two lines after, like so

unpaidMembers[name] = lastname, email

your program will still crash at the same place, because .items() still won't give you 3-tuples but rather something that has this structure: (name, (lastname, email))

good news is, python can handle this

for name, (lastname, email) in unpaidMembers.items():


How to pause javascript code execution for 2 seconds

This Link might be helpful for you.

Every time I've wanted a sleep in the middle of my function, I refactored to use a setTimeout().

JUnit 4 compare Sets

I like the solution of Hans-Peter Störr... But I think it is not quite correct. Sadly containsInAnyOrder does not accept a Collection of objetcs to compare to. So it has to be a Collection of Matchers:

assertThat(set1, containsInAnyOrder(

The import are:

import static;
import static org.hamcrest.Matchers.containsInAnyOrder;
import static org.junit.Assert.assertThat;

Regular expression to allow spaces between words

This one worked for me

([\w ]+)

How to tell if homebrew is installed on Mac OS X

[ ! -f "`which brew`" ] && echo "not installed"

Explaination: If brew is not installed run command after &&

How to remove whitespace from a string in typescript?


The trim() method removes whitespace from both sides of a string.



You can use a Javascript replace method to remove white space like

"hello world".replace(/\s/g, "");


var out = "hello world".replace(/\s/g, "");_x000D_

Read a javascript cookie by name

Use the RegExp constructor and multiple replacements to clarify the syntax:

function getCook(cookiename) 
  // Get name followed by anything except a semicolon
  var cookiestring=RegExp(cookiename+"=[^;]+").exec(document.cookie);
  // Return everything after the equal sign, or an empty string if the cookie name not found
  return decodeURIComponent(!!cookiestring ? cookiestring.toString().replace(/^[^=]+./,"") : "");

//Sample usage
var cookieValue = getCook('MYBIGCOOKIE');

How to check if a key exists in Json Object and get its value

containerObject = new JSONObject(container);
if (containerObject.has("video")) { 
   //get Value of video

How to set the max value and min value of <input> in html5 by javascript or jquery?

Try this:

<input type="number" max="???" min="???" step="0.5" id="myInput"/>

   "max" : 10,
   "min" : 2

Note:This will set max and min value only to single input

C# - Simplest way to remove first occurrence of a substring from another string

int index = sourceString.IndexOf(removeString);
string cleanPath = (index < 0)
    ? sourceString
    : sourceString.Remove(index, removeString.Length);

How do you write multiline strings in Go?

Use raw string literals for multi-line strings:

func main(){
    multiline := `line 
by line
and line
after line`

Raw string literals

Raw string literals are character sequences between back quotes, as in `foo`. Within the quotes, any character may appear except back quote.

A significant part is that is raw literal not just multi-line and to be multi-line is not the only purpose of it.

The value of a raw string literal is the string composed of the uninterpreted (implicitly UTF-8-encoded) characters between the quotes; in particular, backslashes have no special meaning...

So escapes will not be interpreted and new lines between ticks will be real new lines.

func main(){
    multiline := `line 
by line \n
and line \n
after line`

    // \n will be just printed. 
    // But new lines are there too.


Possibly you have long line which you want to break and you don't need new lines in it. In this case you could use string concatenation.

func main(){
    multiline := "line " +
            "by line " +
            "and line " +
            "after line"

    fmt.Print(multiline) // No new lines here

Since " " is interpreted string literal escapes will be interpreted.

func main(){
    multiline := "line " +
            "by line \n" +
            "and line \n" +
            "after line"

    fmt.Print(multiline) // New lines as interpreted \n

Twitter Bootstrap Tabs: Go to Specific Tab on Page Reload or Hyperlink

While the JavaScript solution provided may work, I went a slightly different way that requires no additional JavaScript, but does require logic in your view. You create a link with a standard URL parameter, like:

<a href = "">My Link</a>

Then you simply detect the value of activeTab to write 'class="active"' in the appropriate <li>

Pseudocode (implement accordingly in your language). Note I've set 'home' tab as a default active if no parameter provided in this example.

$activetabhome = (params.activeTab is null or params.activeTab == 'home') ? 'class="active"' : '';
$activetabprofile = (params.activeTab == 'profile') ? 'class="active"' : '';

<li $activetabhome><a href="#home">Home</a></li>
<li $activetabprofile><a href="#profile">Profile</a></li>

What is the precise meaning of "ours" and "theirs" in git?

I know it doesn't explain the meaning but I've made myself a little image, as reference to remind which one to use:

enter image description here

Hope it helps!

PS - Give a check also to the link in Nitay's answer

How to make external HTTP requests with Node.js

NodeJS supports http.request as a standard module:

var http = require('http');

var options = {
  host: '',
  port: 80,
  path: '/foo.html'

http.get(options, function(resp){
  resp.on('data', function(chunk){
    //do something with chunk
}).on("error", function(e){
  console.log("Got error: " + e.message);

How can I get the "network" time, (from the "Automatic" setting called "Use network-provided values"), NOT the time on the phone?

I didn't know, but found the question interesting. So I dug in the android code... Thanks open-source :)

The screen you show is DateTimeSettings. The checkbox "Use network-provided values" is associated to the shared preference String KEY_AUTO_TIME = "auto_time"; and also to Settings.System.AUTO_TIME

This settings is observed by an observed called mAutoTimeObserver in the 2 network ServiceStateTrackers: GsmServiceStateTracker and CdmaServiceStateTracker.

Both implementations call a method called revertToNitz() when the settings becomes true. Apparently NITZ is the equivalent of NTP in the carrier world.

Bottom line: You can set the time to the value provided by the carrier thanks to revertToNitz(). Unfortunately, I haven't found a mechanism to get the network time. If you really need to do this, I'm afraid, you'll have to copy these ServiceStateTrackers implementations, catch the intent raised by the framework (I suppose), and add a getter to mSavedTime.

Do conditional INSERT with SQL?

If you're looking to do an "upsert" one of the most efficient ways currently in SQL Server for single rows is this:

UPDATE myTable ...

    INSERT INTO myTable ....

You can also use the MERGE syntax if you're doing this with sets of data rather than single rows.

If you want to INSERT and not UPDATE then you can just write your single INSERT statement and use WHERE NOT EXISTS (SELECT ...)

How do I encode URI parameter values?

Mmhh I know you've already discarded URLEncoder, but despite of what the docs say, I decided to give it a try.

You said:

For example, given an input:

I expect the output:



public class URLEncodeSample {
    public static void main( String [] args ) throws Throwable {
        System.out.println( URLEncoder.encode( args[0], "UTF-8" ));


C:\oreyes\samples\java\URL>java URLEncodeSample ""

As expected.

What would be the problem with this?

Get decimal portion of a number with JavaScript

If precision matters and you require consistent results, here are a few propositions that will return the decimal part of any number as a string, including the leading "0.". If you need it as a float, just add var f = parseFloat( result ) in the end.

If the decimal part equals zero, "0.0" will be returned. Null, NaN and undefined numbers are not tested.

1. String.split

var nstring = (n + ""),
    narray  = nstring.split("."),
    result  = "0." + ( narray.length > 1 ? narray[1] : "0" );

2. String.substring, String.indexOf

var nstring = (n + ""),
    nindex  = nstring.indexOf("."),
    result  = "0." + (nindex > -1 ? nstring.substring(nindex + 1) : "0");

3. Math.floor, Number.toFixed, String.indexOf

var nstring = (n + ""),
    nindex  = nstring.indexOf("."),
    result  = ( nindex > -1 ? (n - Math.floor(n)).toFixed(nstring.length - nindex - 1) : "0.0");

4. Math.floor, Number.toFixed, String.split

var nstring = (n + ""),
    narray  = nstring.split("."),
    result  = (narray.length > 1 ? (n - Math.floor(n)).toFixed(narray[1].length) : "0.0");

Here is a jsPerf link:

We can see that proposition #2 is the fastest.

Java 8 stream reverse order

How about reversing the Collection backing the stream prior?

import java.util.Collections;
import java.util.List;

public void reverseTest(List<Integer> sampleCollection) {
    Collections.reverse(sampleCollection); // remember this reverses the elements in the list, so if you want the original input collection to remain untouched clone it first. -> {
      // you op here

Failed: Error in connection establishment: net::ERR_CONNECTION_REFUSED

In my case the answer is pretty simple. Please check carefully the hardcoded url port: it is 8080. For some reason the value has changed to: for example 3030.

Just refresh the port in your ajax url string to the appropriate one.

conn = new WebSocket('ws://localhost:3030'); //should solve the issue

Reading file contents on the client-side in javascript in various browsers

In order to read a file chosen by the user, using a file open dialog, you can use the <input type="file"> tag. You can find information on it from MSDN. When the file is chosen you can use the FileReader API to read the contents.

function onFileLoad(elementId, event) {_x000D_
    document.getElementById(elementId).innerText =;_x000D_
function onChooseFile(event, onLoadFileHandler) {_x000D_
    if (typeof window.FileReader !== 'function')_x000D_
        throw ("The file API isn't supported on this browser.");_x000D_
    let input =;_x000D_
    if (!input)_x000D_
        throw ("The browser does not properly implement the event object");_x000D_
    if (!input.files)_x000D_
        throw ("This browser does not support the `files` property of the file input.");_x000D_
    if (!input.files[0])_x000D_
        return undefined;_x000D_
    let file = input.files[0];_x000D_
    let fr = new FileReader();_x000D_
    fr.onload = onLoadFileHandler;_x000D_
<input type='file' onchange='onChooseFile(event, onFileLoad.bind(this, "contents"))' />_x000D_
<p id="contents"></p>

Get current folder path

string appPath = System.IO.Path.GetDirectoryName(Application.ExecutablePath);

From Path.GetDirectoryName

Returns the directory information for the specified path string.

From Application.ExecutablePath

Gets the path for the executable file that started the application, including the executable name.

How to align a <div> to the middle (horizontally/width) of the page

.middle {
   margin:0 auto;
   text-align: center;

/* it brings div to center */

How do I bind to list of checkbox values with AngularJS?

I think the following way is more clear and useful for nested ng-repeats. Check it out on Plunker.

Quote from this thread:

<html ng-app="plunker">
        <script src=""></script>

    <body ng-controller="MainCtrl">
        <div ng-repeat="tab in mytabs">

            <div ng-repeat="val in tab.values">
                <input type="checkbox" ng-change="checkValues()" ng-model="val.checked"/>

        <pre> {{selected}} </pre>

                var app = angular.module('plunker', []);

                app.controller('MainCtrl', function ($scope,$filter) {
                    $scope.mytabs = [
                 name: "tab1",
                 values: [
                     { value: "value1",checked:false },
                     { value: "value2", checked: false },
                     { value: "value3", checked: false },
                     { value: "value4", checked: false }
                 name: "tab2",
                 values: [
                     { value: "value1", checked: false },
                     { value: "value2", checked: false },
                     { value: "value3", checked: false },
                     { value: "value4", checked: false }
                    $scope.selected = []
                    $scope.checkValues = function () {
                        angular.forEach($scope.mytabs, function (value, index) {
                         var selectedItems = $filter('filter')(value.values, { checked: true });
                         angular.forEach(selectedItems, function (value, index) {


Trigger change event <select> using jquery

To select an option, use .val('value-of-the-option') on the select element. To trigger the change element, use .change() or .trigger('change').

The problems in your code are the comma instead of the dot in $('.check'),trigger('change'); and the fact that you call it before binding the event handler.

How to style components using makeStyles and still have lifecycle methods in Material UI?

Hi instead of using hook API, you should use Higher-order component API as mentioned here

I'll modify the example in the documentation to suit your need for class component

import React from 'react';
import PropTypes from 'prop-types';
import { withStyles } from '@material-ui/styles';
import Button from '@material-ui/core/Button';

const styles = theme => ({
  root: {
    background: 'linear-gradient(45deg, #FE6B8B 30%, #FF8E53 90%)',
    border: 0,
    borderRadius: 3,
    boxShadow: '0 3px 5px 2px rgba(255, 105, 135, .3)',
    color: 'white',
    height: 48,
    padding: '0 30px',

class HigherOrderComponentUsageExample extends React.Component {
    const { classes } = this.props;
    return (
      <Button className={classes.root}>This component is passed to an HOC</Button>

HigherOrderComponentUsageExample.propTypes = {
  classes: PropTypes.object.isRequired,

export default withStyles(styles)(HigherOrderComponentUsageExample);

Why should I use var instead of a type?

In this case it is just coding style.

Use of var is only necessary when dealing with anonymous types.
In other situations it's a matter of taste.

How to programmatically send SMS on the iPhone?


If you could send an SMS within a program on the iPhone, you'll be able to write games that spam people in the background. I'm sure you really want to have spams from your friends, "Try out this new game! It roxxers my boxxers, and yours will be too!!!!! If you sign up now you'll get 3,200 RB points!!"

Apple has restrictions for automated (or even partially automated) SMS and dialing operations. (Imagine if the game instead dialed 911 at a particular time of day)

Your best bet is to set up an intermediate server on the internet that uses an online SMS sending service and send the SMS via that route if you need complete automation. (ie, your program on the iPhone sends a UDP packet to your server, which sends the real SMS)

iOS 4 Update

iOS 4, however, now provides a viewController you can import into your application. You prepopulate the SMS fields, then the user can initiate the SMS send within the controller. Unlike using the "SMS:..." url format, this allows your application to stay open, and allows you to populate both the to and the body fields. You can even specify multiple recipients.

This prevents applications from sending automated SMS without the user explicitly aware of it. You still cannot send fully automated SMS from the iPhone itself, it requires some user interaction. But this at least allows you to populate everything, and avoids closing the application.

The MFMessageComposeViewController class is well documented, and tutorials show how easy it is to implement.

iOS 5 Update

iOS 5 includes messaging for iPod touch and iPad devices, so while I've not yet tested this myself, it may be that all iOS devices will be able to send SMS via MFMessageComposeViewController. If this is the case, then Apple is running an SMS server that sends messages on behalf of devices that don't have a cellular modem.

iOS 6 Update

No changes to this class.

iOS 7 Update

You can now check to see if the message medium you are using will accept a subject or attachments, and what kind of attachments it will accept. You can edit the subject and add attachments to the message, where the medium allows it.

iOS 8 Update

No changes to this class.

iOS 9 Update

No changes to this class.

iOS 10 Update

No changes to this class.

iOS 11 Update

No significant changes to this class

Limitations to this class

Keep in mind that this won't work on phones without iOS 4, and it won't work on the iPod touch or the iPad, except, perhaps, under iOS 5. You must either detect the device and iOS limitations prior to using this controller, or risk restricting your app to recently upgraded 3G, 3GS, and 4 iPhones.

However, an intermediate server that sends SMS will allow any and all of these iOS devices to send SMS as long as they have internet access, so it may still be a better solution for many applications. Alternately, use both, and only fall back to an online SMS service when the device doesn't support it.

Getting value of HTML Checkbox from onclick/onchange events

Use this

<input type="checkbox" onclick="onClickHandler()" id="box" />

function onClickHandler(){
    var chk=document.getElementById("box").value;

    //use this value


Removing numbers from string

Would this work for your situation?

>>> s = '12abcd405'
>>> result = ''.join([i for i in s if not i.isdigit()])
>>> result

This makes use of a list comprehension, and what is happening here is similar to this structure:

no_digits = []
# Iterate through the string, adding non-numbers to the no_digits list
for i in s:
    if not i.isdigit():

# Now join all elements of the list with '', 
# which puts all of the characters together.
result = ''.join(no_digits)

As @AshwiniChaudhary and @KirkStrauser point out, you actually do not need to use the brackets in the one-liner, making the piece inside the parentheses a generator expression (more efficient than a list comprehension). Even if this doesn't fit the requirements for your assignment, it is something you should read about eventually :) :

>>> s = '12abcd405'
>>> result = ''.join(i for i in s if not i.isdigit())
>>> result

Angular 2 Date Input not binding to date value

As per HTML5, you can use input type="datetime-local" instead of input type="date".

It will allow the [(ngModel)] directive to read and write value from input control.

Note: If the date string contains 'Z' then to implement above solution, you need to trim the 'Z' character from date.

For more details, please go through this link on mozilla docs.

How to start an Android application from the command line?

You can use:

adb shell monkey -p -c android.intent.category.LAUNCHER 1

This will start the LAUNCHER Activity of the application using monkeyrunner test tool.

Telnet is not recognized as internal or external command

You can try using Putty (freeware). It is mainly known as a SSH client, but you can use for Telnet login as well

Get data from file input in JQuery

input file element:

<input type="file" id="fileinput" />

get file :

var myFile = $('#fileinput').prop('files');

What are pipe and tap methods in Angular tutorial?

You are right, the documentation lacks of those methods. However when I dug into rxjs repository, I found nice comments about tap (too long to paste here) and pipe operators:

   * Used to stitch together functional operators into a chain.
   * @method pipe
   * @return {Observable} the Observable result of all of the operators having
   * been called in the order they were passed in.
   * @example
   * import { map, filter, scan } from 'rxjs/operators';
   * Rx.Observable.interval(1000)
   *   .pipe(
   *     filter(x => x % 2 === 0),
   *     map(x => x + x),
   *     scan((acc, x) => acc + x)
   *   )
   *   .subscribe(x => console.log(x))

In brief:

Pipe: Used to stitch together functional operators into a chain. Before we could just do observable.filter().map().scan(), but since every RxJS operator is a standalone function rather than an Observable's method, we need pipe() to make a chain of those operators (see example above).

Tap: Can perform side effects with observed data but does not modify the stream in any way. Formerly called do(). You can think of it as if observable was an array over time, then tap() would be an equivalent to Array.forEach().

git discard all changes and pull from upstream

I finally realized now that instead of

git fetch --all && git reset --hard origin/master

it should be

git fetch --all && git reset --hard origin/<branch_name>

instead (if one works on a different branch)

How do I execute a MS SQL Server stored procedure in java/jsp, returning table data?

Thank to Brian for the code. I was trying to connect to the sql server with {call spname(?,?)} and I got errors, but when I change my code to exec sp... it works very well.

I post my code in hope this helps others with problems like mine:

ResultSet rs = null;
PreparedStatement cs=null;
Connection conn=getJNDIConnection();

try {
    cs=conn.prepareStatement("exec sp_name ?,?,?,?,?,?,?");

    cs.setString(1, "valueA");

    cs.setString(2, "valueB");

    cs.setString(3, "0418");

    //commented, because no need to register parameters out!, I got results from the resultset. 
    //cs.registerOutParameter(1, Types.VARCHAR);
    //cs.registerOutParameter(2, Types.VARCHAR);

    rs = cs.executeQuery();
    ArrayList<ObjectX> listaObjectX = new ArrayList<ObjectX>();
    while ( {

        ObjectX to = new ObjectX();


    return listaObjectX;
     } catch (SQLException se) {
        System.out.println("Error al ejecutar SQL"+ se.getMessage());
        throw new IllegalArgumentException("Error al ejecutar SQL: " + se.getMessage());

    } finally {

        try {


        } catch (SQLException ex) {

form action with javascript

Absolutely valid.

    <form action="javascript:alert('Hello there, I am being submitted');">
        <button type="submit">
            Let's do it
    <!-- Tested in Firefox, Chrome, Edge and Safari -->

So for a short answer: yes, this is an option, and a nice one. It says "when submitted, please don't go anywhere, just run this script" - quite to the point.

A minor improvement

To let the event handler know which form we're dealing with, it would seem an obvious way to pass on the sender object:

    <form action="javascript:myFunction(this)">  <!-- should work, but it won't -->

But instead, it will give you undefined. You can't access it because javascript: links live in a separate scope. Therefore I'd suggest the following format, it's only 13 characters more and works like a charm:

    <form action="javascript:;" onsubmit="myFunction(this)">  <!-- now you have it! -->

... now you can access the sender form properly. (You can write a simple "#" as action, it's quite common - but it has a side effect of scrolling to the top when submitting.)

Again, I like this approach because it's effortless and self-explaining. No "return false", no jQuery/domReady, no heavy weapons. It just does what it seems to do. Surely other methods work too, but for me, this is The Way Of The Samurai.

A note on validation

Forms only get submitted if their onsubmit event handler returns something truthy, so you can easily run some preemptive checks:

    <form action="/something.php" onsubmit="return isMyFormValid(this)">

Now isMyFormValid will run first, and if it returns false, server won't even be bothered. Needless to say, you will have to validate on server side too, and that's the more important one. But for quick and convenient early detection this is fine.

get parent's view from a layout

You can get ANY view by using the code below


EDIT: This works on Kotlin. In Java, you may need to do something like this=


I learned getCurrentFocus() function from: @JFreeman 's answer

Why is conversion from string constant to 'char*' valid in C but invalid in C++

Up through C++03, your first example was valid, but used a deprecated implicit conversion--a string literal should be treated as being of type char const *, since you can't modify its contents (without causing undefined behavior).

As of C++11, the implicit conversion that had been deprecated was officially removed, so code that depends on it (like your first example) should no longer compile.

You've noted one way to allow the code to compile: although the implicit conversion has been removed, an explicit conversion still works, so you can add a cast. I would not, however, consider this "fixing" the code.

Truly fixing the code requires changing the type of the pointer to the correct type:

char const *p = "abc"; // valid and safe in either C or C++.

As to why it was allowed in C++ (and still is in C): simply because there's a lot of existing code that depends on that implicit conversion, and breaking that code (at least without some official warning) apparently seemed to the standard committees like a bad idea.

MySQL set current date in a DATETIME field on insert

    SET NEW.created_date = NOW();

How do I access (read, write) Google Sheets spreadsheets with Python?

This thread seems to be quite old. If anyone's still looking, the steps mentioned here : work very well.

import gspread
from oauth2client.service_account import ServiceAccountCredentials
import os


scope = ['',

creds = ServiceAccountCredentials.from_json_keyfile_name('client_secret.json', scope)
gc = gspread.authorize(creds)
wks ="Trial_Sheet").sheet1
wks.update_acell('H3', "I'm here!")

Make sure to drop your credentials json file in your current directory. Rename it as client_secret.json.

You might run into errors if you don't enable Google Sheet API with your current credentials.

Maximize a window programmatically and prevent the user from changing the windows state

Change the property WindowState to System.Windows.Forms.FormWindowState.Maximized, in some cases if the older answers doesn't works.

So the window will be maximized, and the other parts are in the other answers.

How to var_dump variables in twig templates?

You can use the debug tag, which is documented here.

{% debug expression.varname %}

Edit: As of Twig 1.5, this has been deprecated and replaced with the new dump function (note, it's now a function and no longer a tag). See also: The accepted answer above.

Best way to extract a subvector from a vector?

You could just use insert

vector<type> myVec { n_elements };

vector<type> newVec;

newVec.insert(newVec.begin(), myVec.begin() + X, myVec.begin() + Y);

Add views below toolbar in CoordinatorLayout

As of Android studio 3.4, You need to put this line in your Layout which holds the RecyclerView.


SQL to Entity Framework Count Group-By

Query syntax

var query = from p in context.People
            group p by into g
            select new
              name = g.Key,
              count = g.Count()

Method syntax

var query = context.People
                   .GroupBy(p =>
                   .Select(g => new { name = g.Key, count = g.Count() });

What properties does @Column columnDefinition make redundant?

columnDefinition will override the sql DDL generated by hibernate for this particular column, it is non portable and depends on what database you are using. You can use it to specify nullable, length, precision, scale... ect.

How to write log to file

os.Open() must have worked differently in the past, but this works for me:

f, err := os.OpenFile("testlogfile", os.O_RDWR | os.O_CREATE | os.O_APPEND, 0666)
if err != nil {
    log.Fatalf("error opening file: %v", err)
defer f.Close()

log.Println("This is a test log entry")

Based on the Go docs, os.Open() can't work for log.SetOutput, because it opens the file "for reading:"

func Open

func Open(name string) (file *File, err error) Open opens the named file for reading. If successful, methods on the returned file can be used for reading; the associated file descriptor has mode O_RDONLY. If there is an error, it will be of type *PathError.


Moved defer f.Close() to after if err != nil check