Programs & Examples On #World of warcraft

World of Warcraft is an MMORPG created by Blizzard Entertainment.

Easiest way to make lua script wait/pause/sleep/block for a few seconds?

Pure Lua uses only what is in ANSI standard C. Luiz Figuereido's lposix module contains much of what you need to do more systemsy things.

Convert a List<T> into an ObservableCollection<T>

ObservableCollection < T > has a constructor overload which takes IEnumerable < T >

Example for a List of int:

ObservableCollection<int> myCollection = new ObservableCollection<int>(myList);

One more example for a List of ObjectA:

ObservableCollection<ObjectA> myCollection = new ObservableCollection<ObjectA>(myList as List<ObjectA>);

Markdown open a new window link

As suggested by this answer:


Works for jekyll or more specifically kramdown, which is a superset of markdown, as part of Jekyll's (default) configuration. But not for plain markdown. ^_^

How to display div after click the button in Javascript?


<div id="myDiv" style="display:none;" class="answer_list" >WELCOME</div>
<input type="button" name="answer" onclick="ShowDiv()" />


function ShowDiv() {
    document.getElementById("myDiv").style.display = "";

Or if you wanted to use jQuery with a nice little animation:

<input id="myButton" type="button" name="answer" />

$('#myButton').click(function() {
  $('#myDiv').toggle('slow', function() {
    // Animation complete.

Reset Entity-Framework Migrations

Considering this still shows up when we search for EF in .NET Core, I'll post my answer here (Since it has haunted me a lot). Note that there are some subtleties with the EF 6 .NET version (No initial command, and you will need to delete "Snapshot" files)

(Tested in .NET Core 2.1)

Here are the steps:

  1. Delete the _efmigrationhistory table.
  2. Search for your entire solution for files that contain Snapshot in their name, such as ApplicationDbContextSnapshot.cs, and delete them.
  3. Rebuild your solution
  4. Run Add-Migration InitialMigration

Please note: You must delete ALL the Snapshot files. I spent countless hours just deleting the database... This will generate an empty migration if you don't do it.

Also, in #3 you can just name your migration however you want.

Here are some additional resources: CORE Migrations generated empty

Reset Entity Framework 7 migrations

Capture key press (or keydown) event on DIV element

(1) Set the tabindex attribute:

<div id="mydiv" tabindex="0" />

(2) Bind to keydown:

 $('#mydiv').on('keydown', function(event) {
       //....your actions for the keys .....

To set the focus on start:

$(function() {

To remove - if you don't like it - the div focus border, set outline: none in the CSS.

See the table of keycodes for more keyCode possibilities.

All of the code assuming you use jQuery.


how to make a full screen div, and prevent size to be changed by content?

I use this approach for drawing a modal overlay.

.fullDiv { width:100%; height:100%; position:fixed }

I believe the distinction here is the use of position:fixed which may or may not be applicable to your use case.

I also add z-index:1000; background:rgba(50,50,50,.7);

Then, the modal content can live inside that div, and any content that was already on the page remains visible in the background but covered by the overlay fully while scrolling.

Pass accepts header parameter to jquery ajax

I use jQuery.getJSON( url [, data ] [, success( data, textStatus, jqXHR ) ] ) for example:

var url="my.php";
$.getJSON( url, myObj )
.done(function( json ) { ... }) /* got JSON from server */
.fail(function( jqxhr, textStatus, error ) {
    var err = textStatus + ", " + error;
    console.log( "Failed to obtain JSON data from server: " + err );
  }); /* failed to get JSON */

getJSON is shorthand for:

  dataType: "json",
  url: url,
  data: data,
  success: success

How to parse a JSON Input stream

If you like to use Jackson Databind (which Spring uses by default for its HttpMessageConverters), then you may use the ObjectMapper.readTree(InputStream) API. For example,

ObjectMapper mapper = new ObjectMapper();
JsonNode json = mapper.readTree(myInputStream);

how to set "camera position" for 3d plots using python/matplotlib?

Try the following code to find the optimal camera position

Move the viewing angle of the plot using the keyboard keys as mentioned in the if clause

Use print to get the camera positions

def move_view(event):
    ax.autoscale(enable=False, axis='both') 
    koef = 8
    zkoef = (ax.get_zbound()[0] - ax.get_zbound()[1]) / koef
    xkoef = (ax.get_xbound()[0] - ax.get_xbound()[1]) / koef
    ykoef = (ax.get_ybound()[0] - ax.get_ybound()[1]) / koef
    ## Map an motion to keyboard shortcuts
    if event.key == "ctrl+down":
        ax.set_ybound(ax.get_ybound()[0] + xkoef, ax.get_ybound()[1] + xkoef)
    if event.key == "ctrl+up":
        ax.set_ybound(ax.get_ybound()[0] - xkoef, ax.get_ybound()[1] - xkoef)
    if event.key == "ctrl+right":
        ax.set_xbound(ax.get_xbound()[0] + ykoef, ax.get_xbound()[1] + ykoef)
    if event.key == "ctrl+left":
        ax.set_xbound(ax.get_xbound()[0] - ykoef, ax.get_xbound()[1] - ykoef)
    if event.key == "down":
        ax.set_zbound(ax.get_zbound()[0] - zkoef, ax.get_zbound()[1] - zkoef)
    if event.key == "up":
        ax.set_zbound(ax.get_zbound()[0] + zkoef, ax.get_zbound()[1] + zkoef)
    # zoom option
    if event.key == "alt+up":
        ax.set_xbound(ax.get_xbound()[0]*0.90, ax.get_xbound()[1]*0.90)
        ax.set_ybound(ax.get_ybound()[0]*0.90, ax.get_ybound()[1]*0.90)
        ax.set_zbound(ax.get_zbound()[0]*0.90, ax.get_zbound()[1]*0.90)
    if event.key == "alt+down":
        ax.set_xbound(ax.get_xbound()[0]*1.10, ax.get_xbound()[1]*1.10)
        ax.set_ybound(ax.get_ybound()[0]*1.10, ax.get_ybound()[1]*1.10)
        ax.set_zbound(ax.get_zbound()[0]*1.10, ax.get_zbound()[1]*1.10)
    # Rotational movement
    if event.key == "shift+up":
    if event.key == "shift+down":
    if event.key == "shift+right":
    if event.key == "shift+left":

    ax.view_init(elev= elev, azim = azim)

    # print which ever variable you want 


fig.canvas.mpl_connect("key_press_event", move_view)

LINQ query on a DataTable

Try this

var row = (from result in dt.AsEnumerable().OrderBy( result => Guid.NewGuid()) select result).Take(3) ; 

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

When I do this, I get a very small square screen instead of a maxed screen. Yet, when I only use the FormWindowState.Maximized, it does give me a full screen. Why is that?

        public partial class Testscherm : Form
            public Testscherm()


                    this.WindowState = FormWindowState.Maximized;
                    this.MaximizeBox = false;
                    this.MinimizeBox = false;
                    this.MinimumSize = this.Size;
                    this.MaximumSize = this.Size;
                    this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;


What is the purpose of the var keyword and when should I use it (or omit it)?

I see people are confused when declaring variables with or without var and inside or outside the function. Here is a deep example that will walk you through these steps:

See the script below in action here at jsfiddle

a = 1;// Defined outside the function without var
var b = 1;// Defined outside the function with var
alert("Starting outside of all functions... \n \n a, b defined but c, d not defined yet: \n a:" + a + "\n b:" + b + "\n \n (If I try to show the value of the undefined c or d, console.log would throw 'Uncaught ReferenceError: c is not defined' error and script would stop running!)");

function testVar1(){
    c = 1;// Defined inside the function without var
    var d = 1;// Defined inside the function with var
    alert("Now inside the 1. function: \n a:" + a + "\n b:" + b + "\n c:" + c + "\n d:" + d);

    a = a + 5;
    b = b + 5;
    c = c + 5;
    d = d + 5;

    alert("After added values inside the 1. function: \n a:" + a + "\n b:" + b + "\n c:" + c + "\n d:" + d);

alert("Run the 1. function again...");

function testVar2(){
    var d = 1;// Defined inside the function with var
    alert("Now inside the 2. function: \n a:" + a + "\n b:" + b + "\n c:" + c + "\n d:" + d);

    a = a + 5;
    b = b + 5;
    c = c + 5;
    d = d + 5;

    alert("After added values inside the 2. function: \n a:" + a + "\n b:" + b + "\n c:" + c + "\n d:" + d);


alert("Now outside of all functions... \n \n Final Values: \n a:" + a + "\n b:" + b + "\n c:" + c + "\n You will not be able to see d here because then the value is requested, console.log would throw error 'Uncaught ReferenceError: d is not defined' and script would stop. \n ");
alert("**************\n Conclusion \n ************** \n \n 1. No matter declared with or without var (like a, b) if they get their value outside the function, they will preserve their value and also any other values that are added inside various functions through the script are preserved.\n 2. If the variable is declared without var inside a function (like c), it will act like the previous rule, it will preserve its value across all functions from now on. Either it got its first value in function testVar1() it still preserves the value and get additional value in function testVar2() \n 3. If the variable is declared with var inside a function only (like d in testVar1 or testVar2) it will will be undefined whenever the function ends. So it will be temporary variable in a function.");
alert("Now check console.log for the error when value d is requested next:");


  1. No matter declared with or without var (like a, b) if they get their value outside the function, they will preserve their value and also any other values that are added inside various functions through the script are preserved.
  2. If the variable is declared without var inside a function (like c), it will act like the previous rule, it will preserve its value across all functions from now on. Either it got its first value in function testVar1() it still preserves the value and get additional value in function testVar2()
  3. If the variable is declared with var inside a function only (like d in testVar1 or testVar2) it will will be undefined whenever the function ends. So it will be temporary variable in a function.

How do I get the SelectedItem or SelectedIndex of ListView in

Private Sub ListView1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles ListView1.Click
        Dim tt As String
        tt = ListView1.SelectedItems.Item(0).SubItems(1).Text
        TextBox1.Text = tt.ToString
End Sub

List of all special characters that need to be escaped in a regex

On @Sorin's suggestion of the Java Pattern docs, it looks like chars to escape are at least:


.NET / C# - Convert char[] to string

Use the constructor of string which accepts a char[]

char[] c = ...;
string s = new string(c);

min and max value of data type in C

Maximum value of any unsigned integral type:

  • ((t)~(t)0) // Generic expression that would work in almost all circumstances.

  • (~(t)0) // If you know your type t have equal or larger size than unsigned int. (This cast forces type promotion.)

  • ((t)~0U) // If you know your type t have smaller size than unsigned int. (This cast demotes type after the unsigned int-type expression ~0U is evaluated.)

Maximum value of any signed integral type:

  • If you have an unsigned variant of type t, ((t)(((unsigned t)~(unsigned t)0)>>1)) would give you the fastest result you need.

  • Otherwise, use this (thanks to @vinc17 for suggestion): (((1ULL<<(sizeof(t)*CHAR_BIT-2))-1)*2+1)

Minimum value of any signed integral type:

You have to know the signed number representation of your machine. Most machines use 2's complement, and so -(((1ULL<<(sizeof(t)*CHAR_BIT-2))-1)*2+1)-1 will work for you.

To detect whether your machine uses 2's complement, detect whether (~(t)0U) and (t)(-1) represent the same thing.

So, combined with above:


will give you the minimum value of any signed integral type.

As an example: Maximum value of size_t (a.k.a. the SIZE_MAX macro) can be defined as (~(size_t)0). Linux kernel source code define SIZE_MAX macro this way.

One caveat though: All of these expressions use either type casting or sizeof operator and so none of these would work in preprocessor conditionals (#if ... #elif ... #endif and like).

(Answer updated for incorpoating suggestions from @chux and @vinc17. Thank you both.)

How can I print a circular structure in a JSON-like format?

In Node.js, you can use util.inspect(object). It automatically replaces circular links with "[Circular]".

Albeit being built-in (no installation is required), you must import it

import * as util from 'util' // has no default export
import { inspect } from 'util' // or directly
// or 
var util = require('util')
To use it, simply call

Also be aware that you can pass options object to inspect (see link above)

inspect(myObject[, options: {showHidden, depth, colors, showProxy, ...moreOptions}])

Please, read and give kudos to commenters below...

node.js require() cache - possible to invalidate?

There's a Simple Module for that (with tests)

We had this exact issue while testing our code (delete cached modules so they can be re-required in a fresh state) so we reviewed all the suggestions of people on the various StackOverflow Questions & Answers and put together a simple node.js module (with tests):

As you would expect, works for both published npm packages and locally defined modules. Windows, Mac, Linux, etc.

Build Status Code Climate maintainability Dependencies Status devDependencies Status

How? (usage)

Usage is pretty simple:


Install the module from npm:

npm install decache --save-dev

Use it in your code:

// require the decache module:
const decache = require('decache');

// require a module that you wrote"
let mymod = require('./mymodule.js');

// use your module the way you need to:
console.log(mymod.count()); // 0   (the initial state for our counter is zero)
console.log(mymod.incrementRunCount()); // 1

// delete the cached module:

mymod = require('./mymodule.js'); // fresh start
console.log(mymod.count()); // 0   (back to initial state ... zero)

If you have any questions or need more examples, please create a GitHub issue:

Open Popup window using javascript

First point is- showing multiple popups is not desirable in terms of usability.

But you can achieve it by using multiple popup names

var newwindow;
function createPop(url, name)
   if (window.focus) {newwindow.focus()}

Better approach will be showing both in a single page in two different iFrames or Divs.


So I will suggest to create a new tab in the test.aspx page to show the report, instead of replacing the image content and placing the pdf.

What does if __name__ == "__main__": do?

The code under if __name__ == '__main__': will be executed only if the module is invoked as a script.

As an example consider the following module


print('This is going to be printed out, no matter what')

if __name__ == '__main__':
    print('This is going to be printed out, only if user invokes the module as a script')

1st possibility: Import in another module


import my_test_module

if __name__ == '__main__':
    print('Hello from')

Now if you invoke


>> 'This is going to be printed out, no matter what'
>> 'Hello from'

Note that only the top-level print() statement in my_test_module is executed.

2nd possibility: Invoke as a script

Now if you run as a Python script, both print() statements will be exectued:


>>> 'This is going to be printed out, no matter what'
>>> 'This is going to be printed out, only if user invokes the module as a script'

For a more comprehensive explanation you can read this blog post.

Insert picture/table in R Markdown

In March I made a deck presentation in slidify, Rmarkdown with impress.js which is a cool 3D framework. My index.Rmdheader looks like

title       : French TER (regional train) monthly regularity
subtitle    : since January 2013
author      : brigasnuncamais
job         : Business Intelligence / Data Scientist consultant
framework   : impressjs     # {io2012, html5slides, shower, dzslides, ...}
highlighter : highlight.js  # {highlight.js, prettify, highlight}
hitheme     : tomorrow      # 
widgets     : []            # {mathjax, quiz, bootstrap}
mode        : selfcontained # {standalone, draft}
knit        : slidify::knit2slides

subdirs are:

/assets /css    /impress-demo.css
        /fig    /unnamed-chunk-1-1.png (generated by included R code)
        /img    /SS850452.png (my image used as background)
        /js     /impress.js
        /layouts/custbg.html # content:--- layout: slide --- {{{ slide.html }}}
        /libraries  /frameworks /impressjs
                    /highlighters   /highlight.js

A slide with image in background code snippet would be in my .Rmd:

<div id="bg">
  <img src="assets/img/SS850452.png" alt="">

Some issues appeared since I last worked on it (photos are no more in background, text it too large on my R plot) but it works fine on my local. Troubles come when I run it on RPubs.

How to update two tables in one statement in SQL Server 2005?

You can update two tables in one query.

UPDATE Table1, Table2 
SET Table1.LastName="DR. XXXXXX", Table2.WAprrs="start,stop" 
WHERE AND"010008";

How to insert TIMESTAMP into my MySQL table?

In addition to checking your table setup to confirm that the field is set to NOT NULL with a default of CURRENT_TIMESTAMP, you can insert date/time values from PHP by writing them in a string format compatible with MySQL.

 $timestamp = date("Y-m-d H:i:s");

This will give you the current date and time in a string format that you can insert into MySQL.

How to find the last day of the month from date?

2 lines code and you are done:

$oDate = new DateTime("2019-11-23");

// now your date object has been updated with last day of month    

// or to just echo you can skip the above line using this
echo $oDate->format("Y-m-t");

Warning: session_start(): Cannot send session cookie - headers already sent by (output started at

You cannot session_start(); when your buffer has already been partly sent.

This mean, if your script already sent informations (something you want, or an error report) to the client, session_start() will fail.

How to actually search all files in Visual Studio

One can access the "Find in Files" window via the drop-down menu selection and search all files in the Entire Solution: Edit > Find and Replace > Find in Files

enter image description here

Other, alternative is to open the "Find in Files" window via the "Standard Toolbars" button as highlighted in the below screen-short:

enter image description here

RegEx to make sure that the string contains at least one lower case char, upper case char, digit and symbol

You can match those three groups separately, and make sure that they all present. Also, [^\w] seems a bit too broad, but if that's what you want you might want to replace it with \W.

Exception 'open failed: EACCES (Permission denied)' on Android

The post 6.0 enforcement of storage permissions can be bypassed if you have a rooted device via these adb commands:

root@msm8996:/ # getenforce
root@msm8996:/ # setenforce 0
setenforce 0
root@msm8996:/ # getenforce

Where do you include the jQuery library from? Google JSAPI? CDN?

I will add this as a reason to locally host these files.

Recently a node in Southern California on TWC has not been able to resolve the domain (for users with IPv4) only so we are not getting the external files. This has been intermittant up until yesterday (now it is persistant.) Because it was intermittant, I was having tons of problems troubleshooting SaaS user issues. Spent countless hours trying to track why some users were having no issues with the software, and others were tanking. In my usual debugging process I'm not in the habit of asking a user if they have IPv6 turned off.

I stumbled on the issue because I myself was using this particular "route" to the file and also am using only IPV4. I discovered the issue with developers tools telling me jquery wasn't loading, then started doing traceroutes etc... to find the real issue.

After this, I will most likely never go back to externally hosted files because: google doesn't have to go down for this to become a problem, and... any one of these nodes can be compromised with DNS hijacking and deliver malicious js instead of the actual file. Always thought I was safe in that a google domain would never go down, now I know any node in between a user and the host can be a fail point.

Could not load file or assembly 'Newtonsoft.Json, Version=, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies

I think AutoCAD hijacked mine. The solution which worked for me was to hijack it back. I got this from - yeah, the Internet works in mysterious ways.

// in your initilizer ...
AppDomain currentDomain = AppDomain.CurrentDomain;
currentDomain.AssemblyResolve += new ResolveEventHandler(MyResolveEventHandler);


private Assembly MyResolveEventHandler(object sender, ResolveEventArgs args)
    if (args.Name.Contains("Newtonsoft.Json"))
        string assemblyFileName = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) + "\\Newtonsoft.Json.dll";
        return Assembly.LoadFrom(assemblyFileName);
        return null;

Switch statement equivalent in Windows batch file

This is simpler to read:

IF "%ID%"=="0" REM do something
IF "%ID%"=="1" REM do something else
IF "%ID%"=="2" REM do another thing
IF %ID% GTR 2  REM default case...

What is the question mark for in a Typescript parameter name

parameter?: type is a shorthand for parameter: type | undefined

Convert base64 string to ArrayBuffer

Using TypedArray.from:

Uint8Array.from(atob(base64_string), c => c.charCodeAt(0))

Performance to be compared with the for loop version of answer.

How to determine programmatically the current active profile using Spring boot

It doesn't matter is your app Boot or just raw Spring. There is just enough to inject org.springframework.core.env.Environment to your bean.

private Environment environment;


How do you post to an iframe?

This function creates a temporary form, then send data using jQuery :

function postToIframe(data,url,target){
    $('body').append('<form action="'+url+'" method="post" target="'+target+'" id="postToIframe"></form>');
        $('#postToIframe').append('<input type="hidden" name="'+n+'" value="'+v+'" />');

target is the 'name' attr of the target iFrame, and data is a JS object :


mysql update column with value from another table

In addition to this answer if you need to change tableB.value according to tableA.value dynamically you can do for example:

SET tableB.value = IF(tableA.value > 0, tableA.value, tableB.value)
WHERE = 'Joe'

How do I set the default Java installation/runtime (Windows)?

Need to remove C:\Program Files (x86)\Common Files\Oracle\Java\javapath from environment and replace by JAVA_HOME which is works fine for me

How to change the color of an svg element?

Open your image using a browser, right-click on the image click on view page source and you will see the svg tag of the image. Cope and paste into your html, then change the fill to the colour of your choice

How to run Nginx within a Docker container without halting?

nginx, like all well-behaved programs, can be configured not to self-daemonize.

Use the daemon off configuration directive described in

Understanding lambda in python and using it to pass multiple arguments

Why do you need to state both 'x' and 'y' before the ':'?

You could actually in some situations(when you have only one argument) do not put the x and y before ":".

>>> flist = []
>>> for i in range(3):
...     flist.append(lambda : i)

but the i in the lambda will be bound by name, so,

>>> flist[0]()
>>> flist[2]()

different from what you may want.

How to reset Android Studio

Linux AnddroidStudio 1.1.0

rm -r ~/.AndroidStudio

What is the best way to implement nested dictionaries?

I used to use this function. its safe, quick, easily maintainable.

def deep_get(dictionary, keys, default=None):
    return reduce(lambda d, key: d.get(key, default) if isinstance(d, dict) else default, keys.split("."), dictionary)

Example :

>>> from functools import reduce
>>> def deep_get(dictionary, keys, default=None):
...     return reduce(lambda d, key: d.get(key, default) if isinstance(d, dict) else default, keys.split("."), dictionary)
>>> person = {'person':{'name':{'first':'John'}}}
>>> print (deep_get(person, ""))
>>> print (deep_get(person, ""))
>>> print (deep_get(person, "", default="No lastname"))
No lastname

How to prevent SIGPIPEs (or handle them properly)

Linux manual said:

EPIPE The local end has been shut down on a connection oriented socket. In this case the process will also receive a SIGPIPE unless MSG_NOSIGNAL is set.

But for Ubuntu 12.04 it isn't right. I wrote a test for that case and I always receive EPIPE withot SIGPIPE. SIGPIPE is genereated if I try to write to the same broken socket second time. So you don't need to ignore SIGPIPE if this signal happens it means logic error in your program.

SQL RANK() over PARTITION on joined tables

As the rank doesn't depend at all from the contacts


   A     |    1     |    15  |   3
   A     |    2     |    32  |   1
   A     |    3     |    29  |   2
   C     |    7     |    61  |   1
   C     |    9     |    30  |   2

Thus :


Change package name for Android in React Native

The simplest one:

npx react-native-rename YourNewAppName -b com.YourCompanyName.YourNewAppName

EF Code First "Invalid column name 'Discriminator'" but no inheritance

Another scenario where this occurs is when you have a base class and one or more subclasses, where at least one of the subclasses introduce extra properties:

class Folder {
  public string Id { get; set; }

  public string Name { get; set; }

// Adds no props, but comes from a different view in the db to Folder:
class SomeKindOfFolder: Folder {

// Adds some props, but comes from a different view in the db to Folder:
class AnotherKindOfFolder: Folder {
  public string FolderAttributes { get; set; }

If these are mapped in the DbContext like below, the "'Invalid column name 'Discriminator'" error occurs when any type based on Folder base type is accessed:

protected override void OnModelCreating(DbModelBuilder modelBuilder)

I found that to fix the issue, we extract the props of Folder to a base class (which is not mapped in OnModelCreating()) like so - OnModelCreating should be unchanged:

class FolderBase {
  public string Id { get; set; }

  public string Name { get; set; }

class Folder: FolderBase {

class SomeKindOfFolder: FolderBase {

class AnotherKindOfFolder: FolderBase {
  public string FolderAttributes { get; set; }

This eliminates the issue, but I don't know why!

MVC - Set selected value of SelectList

Use LINQ and add the condition on the "selected" as a question mark condition.

    var listSiteId = (from site in db.GetSiteId().ToList()
                                      select new SelectListItem
                                          Value = site.SITEID,
                                          Text = site.NAME,
                                          Selected = (dimension.DISPLAYVALUE == site.SITEID) ? true : false,
                    ViewBag.SiteId = listSiteId;

Setting up a JavaScript variable from Spring model by using Thymeleaf

Thymeleaf 3 now:

  • Display a constant:

    <script th:inline="javascript">
    var MY_URL = /*[[${T(}]]*/ "";
  • Display a variable:

    var message = [[${message}]];
  • Or in a comment to have a valid JavaScript code when you open your template file in a static manner (without executing it at a server).

    Thymeleaf calls this: JavaScript natural templates

    var message = /*[[${message}]]*/ "";

    Thymeleaf will ignore everything we have written after the comment and before the semicolon.

More info:

jQuery how to bind onclick event to dynamically added HTML element

A little late to the party but I thought I would try to clear up some common misconceptions in jQuery event handlers. As of jQuery 1.7, .on() should be used instead of the deprecated .live(), to delegate event handlers to elements that are dynamically created at any point after the event handler is assigned.

That said, it is not a simple of switching live for on because the syntax is slightly different:

New method (example 1):

$(document).on('click', '#someting', function(){


Deprecated method (example 2):



As shown above, there is a difference. The twist is .on() can actually be called similar to .live(), by passing the selector to the jQuery function itself:

Example 3:

$('#something').on('click', function(){


However, without using $(document) as in example 1, example 3 will not work for dynamically created elements. The example 3 is absolutely fine if you don't need the dynamic delegation.

Should $(document).on() be used for everything?

It will work but if you don't need the dynamic delegation, it would be more appropriate to use example 3 because example 1 requires slightly more work from the browser. There won't be any real impact on performance but it makes sense to use the most appropriate method for your use.

Should .on() be used instead of .click() if no dynamic delegation is needed?

Not necessarily. The following is just a shortcut for example 3:



The above is perfectly valid and so it's really a matter of personal preference as to which method is used when no dynamic delegation is required.


How to do a less than or equal to filter in Django queryset?

Less than or equal:


Greater than or equal:


Likewise, lt for less than and gt for greater than. You can find them all in the documentation.

How to write a PHP ternary operator

A Ternary is not a good solution for what you want. It will not be readable in your code, and there are much better solutions available.

Why not use an array lookup "map" or "dictionary", like so:

$vocations = array(
    1 => "Sorcerer",
    2 => "Druid",
    3 => "Paladin",

echo $vocations[$result->vocation];

A ternary for this application would end up looking like this:

echo($result->group_id == 1 ? "Player" : ($result->group_id == 2 ? "Gamemaster" : ($result->group_id == 3 ? "God" : "unknown")));

Why is this bad? Because - as a single long line, you would get no valid debugging information if something were to go wrong here, the length makes it difficult to read, plus the nesting of the multiple ternaries just feels odd.

A Standard Ternary is simple, easy to read, and would look like this:

$value = ($condition) ? 'Truthy Value' : 'Falsey Value';


echo ($some_condition) ? 'The condition is true!' : 'The condition is false.';

A ternary is really just a convenient / shorter way to write a simple if else statement. The above sample ternary is the same as:

if ($some_condition) {
    echo 'The condition is true!';
} else {
    echo 'The condition is false!';

However, a ternary for a complex logic quickly becomes unreadable, and is no longer worth the brevity.

echo($result->group_id == 1 ? "Player" : ($result->group_id == 2 ? "Gamemaster" : ($result->group_id == 3 ? "God" : "unknown")));

Even with some attentive formatting to spread it over multiple lines, it's not very clear:

echo($result->group_id == 1 
    ? "Player" 
    : ($result->group_id == 2 
        ? "Gamemaster" 
        : ($result->group_id == 3 
            ? "God" 
            : "unknown")));

Update GCC on OSX

The following recipe using Homebrew worked for me to update to gcc/g++ 4.7:

$ brew tap SynthiNet/synthinet
$ brew install gcc47

Found it on a post here.

could not extract ResultSet in hibernate

Another solution is add @JsonIgnore :

@OneToMany(mappedBy="catalog", fetch = FetchType.LAZY)
private Set<Product> products = new HashSet<Product>(0);

Casting objects in Java

The example you are referring to is called Upcasting in java.

It creates a subclass object with a super class variable pointing to it.

The variable does not change, it is still the variable of the super class but it is pointing to the object of subclass.

For example lets say you have two classes Machine and Camera ; Camera is a subclass of Machine

class Machine{

    public void start(){

        System.out.println("Machine Started");

class Camera extends Machine{
     public void start(){

            System.out.println("Camera Started");
     public void snap(){
         System.out.println("Photo taken");
Machine machine1 = new Camera();

If you execute the above statements it will create an instance of Camera class with a reference of Machine class pointing to it.So, now the output will be "Camera Started" The variable is still a reference of Machine class. If you attempt machine1.snap(); the code will not compile

The takeaway here is all Cameras are Machines since Camera is a subclass of Machine but all Machines are not Cameras. So you can create an object of subclass and point it to a super class refrence but you cannot ask the super class reference to do all the functions of a subclass object( In our example machine1.snap() wont compile). The superclass reference has access to only the functions known to the superclass (In our example machine1.start()). You can not ask a machine reference to take a snap. :)

List method to delete last element in list as well as all elements

To delete the last element of the lists, you could use:

def deleteLast(self):
    if self.Ans:
        del self.Ans[-1]
    if self.masses:
        del self.masses[-1]

How to get the system uptime in Windows?

Two ways to do that..

Option 1:

1.  Go to "Start" -> "Run".

2.  Write "CMD" and press on "Enter" key.

3.  Write the command "net statistics server" and press on "Enter" key.

4.  The line that start with "Statistics since …" provides the time that the server was up from.

  The command "net stats srv" can be use instead.

Option 2:

Uptime.exe Tool Allows You to Estimate Server Availability with Windows NT 4.0 SP4 or Higher

Hope it helped you!!

How do I overload the [] operator in C#

The [] operator is called an indexer. You can provide indexers that take an integer, a string, or any other type you want to use as a key. The syntax is straightforward, following the same principles as property accessors.

For example, in your case where an int is the key or index:

public int this[int index]
    get => GetValue(index);

You can also add a set accessor so that the indexer becomes read and write rather than just read-only.

public int this[int index]
    get => GetValue(index);
    set => SetValue(index, value);

If you want to index using a different type, you just change the signature of the indexer.

public int this[string index]

How to set JAVA_HOME path on Ubuntu?

add JAVA_HOME to the file:


for it to be available to the entire system (you would need to restart Ubuntu though)

How to find a whole word in a String in java

Use regex + word boundaries as others answered.

"I will come and meet you at the 123woods".matches(".*\\b123woods\\b.*");

will be true.

"I will come and meet you at the 123woods".matches(".*\\bwoods\\b.*");

will be false.

Python Requests package: Handling xml response

requests does not handle parsing XML responses, no. XML responses are much more complex in nature than JSON responses, how you'd serialize XML data into Python structures is not nearly as straightforward.

Python comes with built-in XML parsers. I recommend you use the ElementTree API:

import requests
from xml.etree import ElementTree

response = requests.get(url)

tree = ElementTree.fromstring(response.content)

or, if the response is particularly large, use an incremental approach:

    response = requests.get(url, stream=True)
    # if the server sent a Gzip or Deflate compressed response, decompress
    # as we read the raw stream:
    response.raw.decode_content = True

    events = ElementTree.iterparse(response.raw)
    for event, elem in events:
        # do something with `elem`

The external lxml project builds on the same API to give you more features and power still.

How to convert Seconds to HH:MM:SS using T-SQL

DECLARE @seconds AS int = 896434;
    CONVERT(varchar, (@seconds / 86400))                --Days
    + ':' +
    CONVERT(varchar, DATEADD(ss, @seconds, 0), 108);    --Hours, Minutes, Seconds



How do I create an executable in Visual Studio 2013 w/ C++?

  1. Click BUILD > Configuration Manager...
  2. Under Project contexts > Configuration, select "Release"
  3. BUILD > Build Solution or Rebuild Solution

Generate random numbers following a normal distribution in C/C++

The comp.lang.c FAQ list shares three different ways to easily generate random numbers with a Gaussian distribution.

You may take a look of it:

Creating a .p12 file

The openssl documentation says that file supplied as the -in argument must be in PEM format.

Turns out that, contrary to the CA's manual, the certificate returned by the CA which I stored in myCert.cer is not PEM format rather it is PKCS7.

In order to create my .p12, I had to first convert the certificate to PEM:

openssl pkcs7 -in myCert.cer -print_certs -out certs.pem

and then execute

openssl pkcs12 -export -out keyStore.p12 -inkey myKey.pem -in certs.pem

Renaming Columns in an SQL SELECT Statement

select column1 as xyz,
      column2 as pqr,

from TableName;

Refresh Excel VBA Function Results

This refreshes the calculation better than Range(A:B).Calculate:

Public Sub UpdateMyFunctions()
    Dim myRange As Range
    Dim rng As Range

    ' Assume the functions are in this range A1:B10.
    Set myRange = ActiveSheet.Range("A1:B10")

    For Each rng In myRange
        rng.Formula = rng.Formula
End Sub

Check if a list contains an item in Ansible

You do not need {{}} in when conditions. What you are searching for is:

- fail: msg="unsupported version"
  when: version not in acceptable_versions

Setting the value of checkbox to true or false with jQuery

var checkbox = $( "#checkbox" );
checkbox.val( checkbox[0].checked ? "true" : "false" );

This will set the value of the checkbox to "true" or "false" (value property is a string), depending whether it's unchecked or checked.

Works in jQuery >= 1.0

Turn off auto formatting in Visual Studio

Follow TOOLS->OPTIONS->Text Editor->CSS->Formatting Choose "Compact Rules" and uncheck "Hiearerchical indentation"

Generating a list of pages (not posts) without the index file

I have never used jekyll, but it's main page says that it uses Liquid, and according to their docs, I think the following should work:

<ul> {% for page in site.pages %}     {% if page.title != 'index' %}     <li><div class="drvce"><a href="{{ page.url }}">{{ page.title }}</a></div></li>     {% endif %} {% endfor %} </ul> 

AddTransient, AddScoped and AddSingleton Services Differences

This image illustrates this concept well. Unfortunately, I could not find the original source of this image, but someone made it, he has shown this concept very well in the form of an image. enter image description here

How to initialize a static array?

If you are creating an array then there is no difference, however, the following is neater:

String[] suit = {

But, if you want to pass an array into a method you have to call it like this:

myMethod(new String[] {"spades", "hearts"});

myMethod({"spades", "hearts"}); //won't compile!

Check if key exists and iterate the JSON array using Python

If all you want is to check if key exists or not

h = {'a': 1}
'b' in h # returns False

If you want to check if there is a value for key

h.get('b') # returns None

Return a default value if actual value is missing

h.get('b', 'Default value')

Checking for empty result (php, pdo, mysql)

$sql = $dbh->prepare("SELECT * from member WHERE member_email = '$username' AND member_password = '$password'");


$fetch = $sql->fetch(PDO::FETCH_ASSOC);

// if not empty result
if (is_array($fetch))  {
    $_SESSION["userMember"] = $fetch["username"];
    $_SESSION["password"] = $fetch["password"];
    echo 'yes this member is registered'; 
}else {
    echo 'empty result!';

Hibernate Error executing DDL via JDBC Statement

you have to be careful because reseved words are not only for table names, also you have to check column names, my mistake was that one of my columns was named "user". If you are using PostgreSQL the correct dialect is: org.hibernate.dialect.PostgreSQLDialect


How can I quantify difference between two images?

A trivial thing to try:

Resample both images to small thumbnails (e.g. 64 x 64) and compare the thumbnails pixel-by-pixel with a certain threshold. If the original images are almost the same, the resampled thumbnails will be very similar or even exactly the same. This method takes care of noise that can occur especially in low-light scenes. It may even be better if you go grayscale.

how to show confirmation alert with three buttons 'Yes' 'No' and 'Cancel' as it shows in MS Word

This cannot be done with the native javascript dialog box, but a lot of javascript libraries include more flexible dialogs. You can use something like jQuery UI's dialog box for this.

See also these very similar questions:

Here's an example, as demonstrated in this jsFiddle:

    <script type="text/javascript" src=""></script>
    <script type="text/javascript" src=""></script>
    <link rel="stylesheet" type="text/css" href="/css/normalize.css">
    <link rel="stylesheet" type="text/css" href="/css/result-light.css">
    <link rel="stylesheet" type="text/css" href="">
    <a class="checked" href="">Click here</a>
    <script type="text/javascript">

        $(function() {
            $('.checked').click(function(e) {
                var dialog = $('<p>Are you sure?</p>').dialog({
                    buttons: {
                        "Yes": function() {alert('you chose yes');},
                        "No":  function() {alert('you chose no');},
                        "Cancel":  function() {
                            alert('you chose cancel');


Export specific rows from a PostgreSQL table as INSERT SQL script

For my use-case I was able to simply pipe to grep.

pg_dump -U user_name --data-only --column-inserts -t nyummy.cimory | grep "tokyo" > tokyo.sql

Entity Framework Query for inner join

from s in db.Services
join sa in db.ServiceAssignments on s.Id equals sa.ServiceId
where sa.LocationId == 1
select s

Where db is your DbContext. Generated query will look like (sample for EF6):

SELECT [Extent1].[Id] AS [Id]
       -- other fields from Services table
FROM [dbo].[Services] AS [Extent1]
INNER JOIN [dbo].[ServiceAssignments] AS [Extent2]
    ON [Extent1].[Id] = [Extent2].[ServiceId]
WHERE [Extent2].[LocationId] = 1

How to give spacing between buttons using bootstrap

using bootstrap you can add <div class="col-sm-1 col-xs-1 col-md-1 col-lg-1"></div> between buttons.

Express.js: how to get remote client address

The headers object has everything you need, just do this:

var ip = req.headers['x-forwarded-for'].split(',')[0];

How to calculate the difference between two dates using PHP?

use this function

//function Diff between Dates
//PARA: Date Should In YYYY-MM-DD Format
// '%y Year %m Month %d Day %h Hours %i Minute %s Seconds' =>  1 Year 3 Month 14 Day 11 Hours 49 Minute 36 Seconds
// '%y Year %m Month %d Day'                       =>  1 Year 3 Month 14 Days
// '%m Month %d Day'                                     =>  3 Month 14 Day
// '%d Day %h Hours'                                   =>  14 Day 11 Hours
// '%d Day'                                                 =>  14 Days
// '%h Hours %i Minute %s Seconds'         =>  11 Hours 49 Minute 36 Seconds
// '%i Minute %s Seconds'                           =>  49 Minute 36 Seconds
// '%h Hours                                          =>  11 Hours
// '%a Days                                                =>  468 Days
function dateDifference($date_1 , $date_2 , $differenceFormat = '%a' )
    $datetime1 = date_create($date_1);
    $datetime2 = date_create($date_2);

    $interval = date_diff($datetime1, $datetime2);

    return $interval->format($differenceFormat);


only set parameter $differenceFormat As your need example I want Diff between to years with months and days your age

dateDifference(date('Y-m-d') , $date , '%y %m %d')

or other format

dateDifference(date('Y-m-d') , $date , '%y-%m-%d')

Jackson JSON: get node name from json-tree

For Jackson 2+ (com.fasterxml.jackson), the methods are little bit different:

Iterator<Entry<String, JsonNode>> nodes = rootNode.get("foo").fields();

while (nodes.hasNext()) {
  Map.Entry<String, JsonNode> entry = (Map.Entry<String, JsonNode>);"key --> " + entry.getKey() + " value-->" + entry.getValue());

How to pass parameters in $ajax POST?

For send parameters in url in POST method You can simply append it to url like this:

    type: 'POST',
    url: 'superman?' + jQuery.param({ f1: "hello1", f2 : "hello2"}),
    // ...

ScriptManager.RegisterStartupScript code not working - why?

Off the top of my head:

  • Use GetType() instead of typeof(Page) in order to bind the script to your actual page class instead of the base class,
  • Pass a key constant instead of Page.UniqueID, which is not that meaningful since it's supposed to be used by named controls,
  • End your Javascript statement with a semicolon,
  • Register the script during the PreRender phase:

protected void Page_PreRender(object sender, EventArgs e)
    ScriptManager.RegisterStartupScript(this, GetType(), "YourUniqueScriptKey", 
        "alert('This pops up');", true);

Uncaught ReferenceError: React is not defined

The displayed error

after that import react

Finally import react-dom

if error is react is not define,please add ==>import React from 'react';

if error is reactDOM is not define,please add ==>import ReactDOM from 'react-dom';

How to open maximized window with Javascript?

The best solution I could find at present time to open a window maximized is (Internet Explorer 11, Chrome 49, Firefox 45):

  var popup ="your_url", "popup", "fullscreen");
  if (popup.outerWidth < screen.availWidth || popup.outerHeight < screen.availHeight)
    popup.resizeTo(screen.availWidth, screen.availHeight);


Note 1: It does not work on Edge (13.1058686). Not sure whether it's a bug or if it's as designed (I've filled a bug report, we'll see what they have to say about it). Here is a workaround:

if (navigator.userAgent.match(/Edge\/\d+/g))
    return"your_url", "popup", "width=" + screen.width + ",height=" + screen.height);

Note 2: moveTo or resizeTo will not work (Access denied) if the window you are opening is on another domain.

Angular 4: InvalidPipeArgument: '[object Object]' for pipe 'AsyncPipe'

You get this message when you've used async in your template, but are referring to an object that isn't an Observable.

So for examples sake, lets' say I had these properties in my class:


Then in my template, I refer to it this way:

{{job | async }}

instead of:

{{job$ | async }}

You wouldn't need the job:Job property if you use the async pipe, but it serves to illustrate a cause of the error.

Html5 Placeholders with .NET MVC 3 Razor EditorFor extension?

I've wrote such a simple class:

public static class WatermarkExtension
    public static MvcHtmlString WatermarkFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression)
        var watermark = ModelMetadata.FromLambdaExpression(expression, html.ViewData).Watermark;
        var htmlEncoded = HttpUtility.HtmlEncode(watermark);
        return new MvcHtmlString(htmlEncoded);

The usage as such:

@Html.TextBoxFor(model => model.AddressSuffix, new {placeholder = Html.WatermarkFor(model => model.AddressSuffix)})

And property in a viewmodel:

[Display(ResourceType = typeof (Resources), Name = "AddressSuffixLabel", Prompt = "AddressSuffixPlaceholder")]
public string AddressSuffix
    get { return _album.AddressSuffix; }
    set { _album.AddressSuffix = value; }

Notice Prompt parameter. In this case I use strings from resources for localization but you can use just strings, just avoid ResourceType parameter.

What is the difference between utf8mb4 and utf8 charsets in MySQL?

UTF-8 is a variable-length encoding. In the case of UTF-8, this means that storing one code point requires one to four bytes. However, MySQL's encoding called "utf8" (alias of "utf8mb3") only stores a maximum of three bytes per code point.

So the character set "utf8"/"utf8mb3" cannot store all Unicode code points: it only supports the range 0x000 to 0xFFFF, which is called the "Basic Multilingual Plane". See also Comparison of Unicode encodings.

This is what (a previous version of the same page at) the MySQL documentation has to say about it:

The character set named utf8[/utf8mb3] uses a maximum of three bytes per character and contains only BMP characters. As of MySQL 5.5.3, the utf8mb4 character set uses a maximum of four bytes per character supports supplemental characters:

  • For a BMP character, utf8[/utf8mb3] and utf8mb4 have identical storage characteristics: same code values, same encoding, same length.

  • For a supplementary character, utf8[/utf8mb3] cannot store the character at all, while utf8mb4 requires four bytes to store it. Since utf8[/utf8mb3] cannot store the character at all, you do not have any supplementary characters in utf8[/utf8mb3] columns and you need not worry about converting characters or losing data when upgrading utf8[/utf8mb3] data from older versions of MySQL.

So if you want your column to support storing characters lying outside the BMP (and you usually want to), such as emoji, use "utf8mb4". See also What are the most common non-BMP Unicode characters in actual use?.

VBA check if file exists

A way that is clean and short:

Public Function IsFile(s)
    IsFile = CreateObject("Scripting.FileSystemObject").FileExists(s)
End Function

How to increase the clickable area of a <a> tag button?

use position css property and set top,right,bottom and left to Zero.. set z-index if needed in my case in i used text-indent because i dont want to show link "text" but if you want to show link "text" , just don't use text-indent

position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
text-indent: -99999px;

Xml serialization - Hide null values

In my case the nullable variables/elements were all String type. So, I simply performed a check and assigned them string.Empty in case of NULL. This way I got rid of the unnecessary nil and xmlns attributes (p3:nil="true" xmlns:p3="

// Example:

myNullableStringElement = varCarryingValue ?? string.Empty

// OR

myNullableStringElement = myNullableStringElement ?? string.Empty

Google OAuth 2 authorization - Error: redirect_uri_mismatch

What you need to do is go back to your Developer Console and go to APIs & Auth > Consent Screen and fill that out. Specifically, the product name.

How to create a fixed sidebar layout with Bootstrap 4?

I'm using the J.S. to fix a sidebar menu. I've tried a lot of solutions with CSS but it's the simplest way to solve it, just add J.S. adding and removing a native BootStrap class: "position-fixed".

The J.S.:

var lateral = false;
function fixar() {

            var element, name, arr;
            element = document.getElementById("minhasidebar");

            if (lateral) {
                element.className = element.className.replace(
                        /\bposition-fixed\b/g, "");
                lateral = false;
            } else {

                name = "position-fixed";
                arr = element.className.split(" ");
                if (arr.indexOf(name) == -1) {
                    element.className += " " + name;
                lateral = true;




        <nav class="sidebar ">
             <div id="minhasidebar">
                 <ul class="nav nav-pills">
                     <li class="nav-item"><a class="nav-link active" 
                     th:href="@{/hoje/inicial}"> <i class="oi oi-clipboard"></i> 

Parse error: Syntax error, unexpected end of file in my PHP code

Avoid this as well <? } ?> make sure you put <?php } ?>

How much does it cost to develop an iPhone application?

I am a very good iPhone app developer, and I charge over $150 per hour for my services. I have a ton of experience building iPhone apps and their server side components. I have also been called in on several occasions to fix offshore developed apps. Here's my take.

  • Design costs money, good design costs lots of money. Expect several designer weeks of work per app screen. Offshore teams do not do design.
  • Server development and infrastructure is critical if the app is to succeed. A slow server response, or an overloaded server will hamper your app, and crimp sales and satisfaction. The server side of the equation will cost the most and take the most time to develop. Those who offshore their server development will find that quality and uptime are both terrible, in my experience.
  • App development if done right takes time too. A professional developer will ensure all HIG rules are followed, the app is properly structured and contains no known errors, it performs well, and it passes the app store validations. Offshore teams just cut code.

I'm just about to release a shopping app for a client. The design work was done by 2 client in-house designers over 2 weeks, quick because they had all the image assets already. Think 2 people x 10 days x 8 hours = ~$24,000. The server side had to be modified to provide data for the iPhone app. We used their in-house team and in-house platform and in-house API, 2 developers, 4 weeks, or about $50,000 and that's because they already have a web shop and API. Cost them about $400,000 to get there (excluding platform). And I wrote the app side in 3 weeks, given that a lot of my code is duplicated from previous projects, another ~$25,000, the cheapest app I ever did.

Total spent: ~$100,000, and that's insanely cheap!

And they will give this away for free so clients will buy from their store from their iPhones.

For your app, Peter, if you have the servers and the APIs and the design, I'd guess at $30,000 to $60,000 depending on complexity. If you do not have the design, double it. If you do not have the APIs, double again...

Encrypt & Decrypt using PyCrypto AES 256

compatible utf-8 encoding

def _pad(self, s):
    s = s.encode()
    res = s + ( - len(s) % * chr( - len(s) %
    return res

How do you fix the "element not interactable" exception?

For those discovering this now and the above answers didn't work, the issue I had was the screen wasn't big enough. I added this when initializing my ChromeDriver, and it fixed the problem:


Error: The 'brew link' step did not complete successfully

I completely uninstalled brew and started again, only to find the same problem again.

Brew appears to work by symlinking the required binaries into your system where other installation methods would typically copy the files.

I found an existing set of node libraries here:


After some head scratching I remembered installing node at the date against this old version and it hadn't been via brew.

I manually deleted this entire folder and successfully linked npm.

This would explain why using brew uninstall or even uninstall brew itself had no effect.

The highest ranked answer puts this very simply, but I thought I'd add my observations about why it's necessary.

I'm guessing a bunch of issues with other brew packages might be caused by old non-brew instances of packages being in the way.

How to change the font on the TextView?

You might want to create static class which will contain all the fonts. That way, you won't create the font multiple times which might impact badly on performance. Just make sure that you create a sub-folder called "fonts" under "assets" folder.

Do something like:

public class CustomFontsLoader {

public static final int FONT_NAME_1 =   0;
public static final int FONT_NAME_2 =   1;
public static final int FONT_NAME_3 =   2;

private static final int NUM_OF_CUSTOM_FONTS = 3;

private static boolean fontsLoaded = false;

private static Typeface[] fonts = new Typeface[3];

private static String[] fontPath = {

 * Returns a loaded custom font based on it's identifier. 
 * @param context - the current context
 * @param fontIdentifier = the identifier of the requested font
 * @return Typeface object of the requested font.
public static Typeface getTypeface(Context context, int fontIdentifier) {
    if (!fontsLoaded) {
    return fonts[fontIdentifier];

private static void loadFonts(Context context) {
    for (int i = 0; i < NUM_OF_CUSTOM_FONTS; i++) {
        fonts[i] = Typeface.createFromAsset(context.getAssets(), fontPath[i]);
    fontsLoaded = true;


This way, you can get the font from everywhere in your application.

How can I generate UUID in C#

I don't know about methods; however, the type to GUID can be done via:

Guid iid = System.Runtime.InteropServices.Marshal.GenerateGuidForType(typeof(IFoo));

Remove ListView items in Android

Try this code, it works for me.

public class Third extends ListActivity {
private ArrayAdapter<String> adapter;
private List<String> liste;
protected void onCreate(Bundle savedInstanceState) {
     String[] values = new String[] { "Android", "iPhone", "WindowsMobile",
                "Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X",
                "Linux", "OS/2" };
     liste = new ArrayList<String>();
     Collections.addAll(liste, values);
     adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, liste);
  protected void onListItemClick(ListView l, View v, int position, long id) {

A project with an Output Type of Class Library cannot be started directly

The strange part is that I don't see a main function anywhere.

That is exactly your problem. The project merely creates a DLL. It has no executable to run.

You will need to add a second project, which is an executable which references the other project, and calls something in it.

Can RDP clients launch remote applications and not desktops

I think Citrix does that kind of thing. Though I'm not sure on specifics as I've only used it a couple of times. I think the one I used was called XenApp but I'm not sure if thats what you're after.

Control the dashed border stroke length and distance between strokes

The native dashed border property value does not offer control over the dashes themselves... so bring on the border-image property!

Brew your own border with border-image

Compatibility: It offers great browser support (IE 11 and all modern browsers). A normal border can be set as a fallback for older browsers.

Let's create these

These borders will display exactly the same cross-browser!

Goal example Goal example with wider gaps

Step 1 - Create a suitable image

This example is 15 pixels wide by 15 pixels high and the gaps are currently 5px wide. It is a .png with transparency.

This is what it looks like in photoshop when zoomed in:

Example Border Image Background Blown Up

This is what it looks like to scale:

Example Border Image Background Actual Size

Controlling gap and stroke length

To create wider / shorter gaps or strokes, widen / shorten the gaps or strokes in the image.

Here is an image with wider 10px gaps:

Larger gaps correctly scaled = Larger gaps to scale

Step 2 - Create the CSS — this example requires 4 basic steps

  1. Define the border-image-source:

  2. Optional - Define the border-image-width:

    border-image-width: 1;

    The default value is 1. It can also be set with a pixel value, percentage value, or as another multiple (1x, 2x, 3x etc). This overrides any border-width set.

  3. Define the border-image-slice:

    In this example, the thickness of the images top, right, bottom and left borders is 2px, and there is no gap outside of them, so our slice value is 2:

    border-image-slice: 2; 

    The slices look like this, 2 pixels from the top, right, bottom and left:

    Slices example

  4. Define the border-image-repeat:

    In this example, we want the pattern to repeat itself evenly around our div. So we choose:

    border-image-repeat: round;

Writing shorthand

The properties above can be set individually, or in shorthand using border-image:

border-image: url("") 2 round;

Complete example

Note the border: dashed 4px #000 fallback. Non-supporting browsers will receive this border.

.bordered {_x000D_
  display: inline-block;_x000D_
  padding: 20px;_x000D_
  /* Fallback dashed border_x000D_
     - the 4px width here is overwritten with the border-image-width (if set)_x000D_
     - the border-image-width can be omitted below if it is the same as the 4px here_x000D_
  border: dashed 4px #000;_x000D_
  /* Individual border image properties */_x000D_
  border-image-source: url("");_x000D_
  border-image-slice: 2;_x000D_
  border-image-repeat: round;  _x000D_
  /* or use the shorthand border-image */_x000D_
  border-image: url("") 2 round;_x000D_
/*The border image of this one creates wider gaps*/_x000D_
.largeGaps {_x000D_
  border-image-source: url("");_x000D_
  margin: 0 20px;_x000D_
<div class="bordered">This is bordered!</div>_x000D_
<div class="bordered largeGaps">This is bordered and has larger gaps!</div>

Can I give the col-md-1.5 in bootstrap?

You cloud also simply override the width of the Column...

<div class="col-md-1" style="width: 12.499999995%"></div>

Since col-md-1 is of width 8.33333333%; simply multiply 8.33333333 * 1.5 and set it as your width.

in bootstrap 4, you will have to override flex and max-width property too:

<div class="col-md-1" style="width: 12.499999995%;
    flex: 0 0 12.499%;max-width: 12.499%;"></div>

How can I view the allocation unit size of a NTFS partition in Vista?

Use diskpart.exe.

Once you are in diskpart select volume <VolumeNumber> then type filesystems.

It should tell you the file system type and the allocation unit size. It will also tell you the supported sizes etc. Previously mentioned fsutil does work, but answer isn't as clear and I couldn't find a syntax to get the same information for a junction point.

Responsive dropdown navbar with angular-ui bootstrap (done in the correct angular kind of way)

My solotion for responsive/dropdown navbar with angular-ui bootstrap (when update to angular 1.5 and, ui-bootrap 1.2.1)

    <link rel="stylesheet" href="/css/app.css">

<nav class="navbar navbar-inverse navbar-fixed-top">
        <div class="container">
            <input type="checkbox" id="navbar-toggle-cbox">
            <div class="navbar-header">
                <label for="navbar-toggle-cbox" class="navbar-toggle" 
                       ng-init="navCollapsed = true" 
                       ng-click="navCollapsed = !navCollapsed"  
                    <span class="sr-only">Toggle navigation</span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                <a class="navbar-brand" href="#">Project name</a>
                 <div id="navbar" class="collapse navbar-collapse"  ng-class="{'in':!navCollapsed}">
                    <ul class="nav navbar-nav">
                        <li class="active"><a href="/view1">Home</a></li>
                        <li><a href="/view2">About</a></li>
                        <li><a href="#">Contact</a></li>
                        <li uib-dropdown>
                            <a href="#" uib-dropdown-toggle>Dropdown <b class="caret"></b></a>
                            <ul uib-dropdown-menu role="menu" aria-labelledby="split-button">
                                <li role="menuitem"><a href="#">Action</a></li>
                                <li role="menuitem"><a href="#">Another action</a></li>                                   



/* show the collapse when navbar toggle is checked */
#navbar-toggle-cbox:checked ~ .collapse {
    display: block;

/* the checkbox used only internally; don't display it */
#navbar-toggle-cbox {

Storing sex (gender) in database

There is already an ISO standard for this; no need to invent your own scheme:

Per the standard, the column should be called "Sex" and the 'closest' data type would be tinyint with a CHECK constraint or lookup table as appropriate.

How can I remove a commit on GitHub?

git push -f origin HEAD^:master

That should "undo" the push.

Waiting for Target Device to Come Online

Like urupvog's answer, make sure that you aren't running any other virtual machines like VirtualBox. When I restarted my computer, AVD worked until I started Vagrant for backend development (then it wouldn't launch).

See Android emulator and virtualbox cannot run at same time for more info.

spring PropertyPlaceholderConfigurer and context:property-placeholder

<context:property-placeholder ... /> is the XML equivalent to the PropertyPlaceholderConfigurer. So, prefer that. The <util:properties/> simply factories a java.util.Properties instance that you can inject.

In Spring 3.1 (not 3.0...) you can do something like this:

public class ServiceConfiguration { 

    @Autowired Environment environment; 

    @Bean public javax.sql.DataSource dataSource( ){ 
        String user = this.environment.getProperty("ds.user");

In Spring 3.0, you can "access" properties defined using the PropertyPlaceHolderConfigurer mechanism using the SpEl annotations:

@Value("${ds.user}") private String user;

If you want to remove the XML all together, simply register the PropertyPlaceholderConfigurer manually using Java configuration. I prefer the 3.1 approach. But, if youre using the Spring 3.0 approach (since 3.1's not GA yet...), you can now define the above XML like this:

public class MySpring3Configuration {     
        public static PropertyPlaceholderConfigurer configurer() { 
             PropertyPlaceholderConfigurer ppc = ...
             return ppc; 

        public class DataSource dataSource(
                @Value("${ds.user}") String user, 
                @Value("${}") String pw, 
                ...) { 
            DataSource ds = ...
            return ds;

Note that the PPC is defined using a static bean definition method. This is required to make sure the bean is registered early, because the PPC is a BeanFactoryPostProcessor - it can influence the registration of the beans themselves in the context, so it necessarily has to be registered before everything else.

Why is char[] preferred over String for passwords?

The short and straightforward answer would be because char[] is mutable while String objects are not.

Strings in Java are immutable objects. That is why they can't be modified once created, and therefore the only way for their contents to be removed from memory is to have them garbage collected. It will be only then when the memory freed by the object can be overwritten, and the data will be gone.

Now garbage collection in Java doesn't happen at any guaranteed interval. The String can thus persist in memory for a long time, and if a process crashes during this time, the contents of the string may end up in a memory dump or some log.

With a character array, you can read the password, finish working with it as soon as you can, and then immediately change the contents.

How to save .xlsx data to file as a blob

This works as of: v0.14.0 of

/* generate array buffer */
var wbout = XLSX.write(wb, {type:"array", bookType:'xlsx'});
/* create data URL */
var url = URL.createObjectURL(new Blob([wbout], {type: 'application/octet-stream'}));
/* trigger download with chrome API */{ url: url, filename: "testsheet.xlsx", saveAs: true });

Form Submit jQuery does not work

Alright, this doesn't apply to the OP's exact situation, but for anyone like myself who comes here facing a similar issue, figure I should throw this out there-- maybe save a headache or two.

If you're using an non-standard "button" to ensure the submit event isn't called:

  <input type="hidden" name="hide" value="1">
  <a href="#" onclick="submitWithChecked(this.form)">Hide Selected</a>

Then, when you try to access this.form in the script, it's going to come up undefined. As I discovered, apparently anchor elements don't have same access to a parent form element the way your standard form elements do.

In such cases, (again, assuming you are intentionally avoiding the submit event for the time-being), you can use a button with type="button"

  <input type="hidden" name="hide" value="1">
  <button type="button" onclick="submitWithChecked(this.form)">Hide Selected</a>

(Addendum 2020: All these years later, I think the more important lesson to take away from this is to check your input. If my function had bothered to check that the argument it received was actually a form element, the problem would have been much easier to catch.)

Jquery function return value

The return statement you have is stuck in the inner function, so it won't return from the outer function. You just need a little more code:

function getMachine(color, qty) {
    var returnValue = null;
    $("#getMachine li").each(function() {
        var thisArray = $(this).text().split("~");
        if(thisArray[0] == color&& qty>= parseInt(thisArray[1]) && qty<= parseInt(thisArray[2])) {
            returnValue = thisArray[3];
            return false; // this breaks out of the each
    return returnValue;

var retval = getMachine(color, qty);

Convert the first element of an array to a string in PHP

implode or join (they're the exact same thing) would work here. Alternatively, you can just call array_pop and get the value of the only element in the array.

Pagination on a list using ng-repeat

I just made a JSFiddle that show pagination + search + order by on each column using Build with Twitter Bootstrap code:

How to compare arrays in JavaScript?

How about using 'includes' with 'forEach'?

    var array1 = [1,2,3];
    var array2 = [1,2,4];
    var array_diff = 0;
    // loop through each element in first array
        // check if second array contains it, return false if not
            array_diff = 1;
            return false;
            array_diff = 0;
    // loop through each element in second array
        // check if first array contains it, return false if not
            array_diff = 1;
            return false;
            array_diff = 0;
    // variable array_diff determines the result
    if(array_diff == 1){
        alert('Arrays are different');
        alert('Arrays are same');

Note: This should work on both sorted and unsorted arrays

How can I force clients to refresh JavaScript files?

One simple way. Edit htaccess

RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_URI} \.(jpe?g|bmp|png|gif|css|js|mp3|ogg)$ [NC]
RewriteCond %{QUERY_STRING} !^(.+?&v33|)v=33[^&]*(?:&(.*)|)$ [NC]
RewriteRule ^ %{REQUEST_URI}?v=33 [R=301,L]

Ajax success event not working

I'm using XML to carry the result back from the php on the server to the webpage and I have had the same behaviour.

In my case the reason was , that the closing tag did not match the opening tag.

header("Content-Type: text/xml");
echo "<?xml version=\"1.0\" encoding=\"utf-8\"?>

How can you run a command in bash over and over until success?

You need to test $? instead, which is the exit status of the previous command. passwd exits with 0 if everything worked ok, and non-zero if the passwd change failed (wrong password, password mismatch, etc...)

while [ $? -ne 0 ]; do

With your backtick version, you're comparing passwd's output, which would be stuff like Enter password and confirm password and the like.

What are Runtime.getRuntime().totalMemory() and freeMemory()?

The names and values are confusing. If you are looking for the total free memory you will have to calculate this value by your self. It is not what you get from freeMemory();.

See the following guide:

Total designated memory, this will equal the configured -Xmx value:


Current allocated free memory, is the current allocated space ready for new objects. Caution this is not the total free available memory:


Total allocated memory, is the total allocated space reserved for the java process:


Used memory, has to be calculated:

usedMemory = Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory();

Total free memory, has to be calculated:

freeMemory = Runtime.getRuntime().maxMemory() - usedMemory;

A picture may help to clarify:

java runtime memory

1052: Column 'id' in field list is ambiguous

In your SELECT statement you need to preface your id with the table you want to choose it from.

SELECT, name, section 
FROM tbl_names
INNER JOIN tbl_section 
   ON =


SELECT, name, section 
FROM tbl_names
INNER JOIN tbl_section 
   ON =

Defining TypeScript callback type

I came across the same error when trying to add the callback to an event listener. Strangely, setting the callback type to EventListener solved it. It looks more elegant than defining a whole function signature as a type, but I'm not sure if this is the correct way to do this.

class driving {
    // the answer from this post - this works
    // private callback: () => void; 

    // this also works!
    private callback:EventListener;

        this.callback = () => this.startJump();
        window.addEventListener("keydown", this.callback);

    startJump():void {
        window.removeEventListener("keydown", this.callback);

Calling a PHP function from an HTML form in the same file

Use SAJAX or switch to JavaScript

Sajax is an open source tool to make programming websites using the Ajax framework — also known as XMLHTTPRequest or remote scripting — as easy as possible. Sajax makes it easy to call PHP, Perl or Python functions from your webpages via JavaScript without performing a browser refresh.

'Property does not exist on type 'never'

if you write Component as React.FC, and using useState(),

just write like this would be helpful:

const [arr, setArr] = useState<any[]>([])

Order a MySQL table by two columns

Default sorting is ascending, you need to add the keyword DESC to both your orders:

ORDER BY article_rating DESC, article_time DESC

How to create multidimensional array

var size = 0;   
 var darray = new Array();
    function createTable(){
        darray[size] = new Array();
        darray[size][0] = $("#chqdate").val();
        darray[size][1]= $("#chqNo").val();
        darray[size][2] = $("#chqNarration").val() ;
        darray[size][3]= $("#chqAmount").val();
        darray[size][4]= $("#chqMode").val();

increase size var after your function.

Get URL of ASP.Net Page in code-behind

If you want to include any unique string on the end, similar to, then use the following

Dim rawUrl As String = Request.RawUrl.ToString()

How to find out if you're using HTTPS without $_SERVER['HTTPS']

$secure_connection = ((!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off') || (!empty($_SERVER['HTTP_HTTPS']) && $_SERVER['HTTP_HTTPS'] != 'off') || $_SERVER['REQUEST_SCHEME'] == 'https' || $_SERVER['SERVER_PORT'] == 443) ? true : false;

Code is checking anything possible and works also on IIS web server. Chrome since v44 do not set header HTTP: 1 so checking HTTP_HTTPS is OK. If this code does not match https it means your webserver or proxy server is poorly configured. Apache itself sets HTTPS flag correctly but there can be problem when you use proxy (e.g. nginx). You must set some header in nginx https virtual host

proxy_set_header   X-HTTPS 1;

and use some Apache module to set HTTPS flag correctly by looking for X-HTTPS from proxy. Search for mod_fakessl, mod_rpaf, etc.

NameError: name 'reduce' is not defined in Python

Or if you use the six library

from six.moves import reduce

Automatic confirmation of deletion in powershell

Add -recurse after the remove-item, also the -force parameter helps remove hidden files e.g.:

gci C:\temp\ -exclude *.svn-base,".svn" -recurse | %{ri $_ -force -recurse}

Where does pip install its packages?

pip show <package name> will provide the location for Windows and macOS, and I'm guessing any system. :)

For example:

> pip show cvxopt
Name: cvxopt
Version: 1.2.0
Location: /usr/local/lib/python2.7/site-packages

@angular/material/index.d.ts' is not a module

Components cannot be further (From Angular 9) imported through general directory

you should add a specified component path like

import {} from '@angular/material'; 

import {} from '@angular/material/input';

Resize image proportionally with CSS?

img {

div {

with this snippet you can do it in a more efficient way

Single-threaded apartment - cannot instantiate ActiveX control

If you used [STAThread] to the main entry of your application and still get the error you may need to make a Thread-Safe call to the control... something like below. In my case with the same problem the following solution worked!

Private void YourFunc(..)
    if (this.InvokeRequired)
        Invoke(new MethodInvoker(delegate()
           // Call your method YourFunc(..);

CSS rotation cross browser with jquery.animate()

Another answer, because jQuery.transit is not compatible with jQuery.easing. This solution comes as an jQuery extension. Is more generic, rotation is a specific case:

    animateStep: function(options) {
        return this.each(function() {
            var elementOptions = $.extend({}, options, {step: options.step.bind($(this))});
            $({x: options.from}).animate({x:}, elementOptions);
    rotate: function(value) {
        return this.css("transform", "rotate(" + value + "deg)");

The usage is as simple as:

$(element).animateStep({from: 0, to: 90, step: $.fn.rotate});

How to return the output of stored procedure into a variable in sql server

You can use the return statement inside a stored procedure to return an integer status code (and only of integer type). By convention a return value of zero is used for success.

If no return is explicitly set, then the stored procedure returns zero.

   CREATE PROCEDURE GetImmediateManager
      @employeeID INT,
      @managerID INT OUTPUT
     SELECT @managerID = ManagerID 
     FROM HumanResources.Employee 
     WHERE EmployeeID = @employeeID

     if @@rowcount = 0 -- manager not found?
       return 1;

And you call it this way:

DECLARE @return_status int;
DECLARE @managerID int;

EXEC @return_status = GetImmediateManager 2, @managerID output;
if @return_status = 1
  print N'Immediate manager not found!';
  print N'ManagerID is ' + @managerID;

You should use the return value for status codes only. To return data, you should use output parameters.

If you want to return a dataset, then use an output parameter of type cursor.

more on RETURN statement

How does HttpContext.Current.User.Identity.Name know which usernames exist?

How does [HttpContext.Current.User] know which usernames exist or do not exist?

Let's look at an example of one way this works. Suppose you are using Forms Authentication and the "OnAuthenticate" event fires. This event occurs "when the application authenticates the current request" (Reference Source).

Up until this point, the application has no idea who you are.

Since you are using Forms Authentication, it first checks by parsing the authentication cookie (usually .ASPAUTH) via a call to ExtractTicketFromCookie. This calls FormsAuthentication.Decrypt (This method is public; you can call this yourself!). Next, it calls Context.SetPrincipalNoDemand, turning the cookie into a user and stuffing it into Context.User (Reference Source).

Abstraction vs Encapsulation in Java

OO Abstraction occurs during class level design, with the objective of hiding the implementation complexity of how the the features offered by an API / design / system were implemented, in a sense simplifying the 'interface' to access the underlying implementation.

The process of abstraction can be repeated at increasingly 'higher' levels (layers) of classes, which enables large systems to be built without increasing the complexity of code and understanding at each layer.

For example, a Java developer can make use of the high level features of FileInputStream without concern for how it works (i.e. file handles, file system security checks, memory allocation and buffering will be managed internally, and are hidden from consumers). This allows the implementation of FileInputStream to be changed, and as long as the API (interface) to FileInputStream remains consistent, code built against previous versions will still work.

Similarly, when designing your own classes, you will want to hide internal implementation details from others as far as possible.

In the Booch definition1, OO Encapsulation is achieved through Information Hiding, and specifically around hiding internal data (fields / members representing the state) owned by a class instance, by enforcing access to the internal data in a controlled manner, and preventing direct, external change to these fields, as well as hiding any internal implementation methods of the class (e.g. by making them private).

For example, the fields of a class can be made private by default, and only if external access to these was required, would a get() and/or set() (or Property) be exposed from the class. (In modern day OO languages, fields can be marked as readonly / final / immutable which further restricts change, even within the class).

Example where NO information hiding has been applied (Bad Practice):

class Foo {
   // BAD - NOT Encapsulated - code external to the class can change this field directly
   // Class Foo has no control over the range of values which could be set.
   public int notEncapsulated;

Example where field encapsulation has been applied:

class Bar {
   // Improvement - access restricted only to this class
   private int encapsulatedPercentageField;

   // The state of Bar (and its fields) can now be changed in a controlled manner
   public void setEncapsulatedField(int percentageValue) {
      if (percentageValue >= 0 && percentageValue <= 100) {
          encapsulatedPercentageField = percentageValue;
      // else throw ... out of range

Example of immutable / constructor-only initialization of a field:

class Baz {
   private final int immutableField;

   public void Baz(int onlyValue) {
      // ... As above, can also check that onlyValue is valid
      immutableField = onlyValue;
   // Further change of `immutableField` outside of the constructor is NOT permitted, even within the same class 

Re : Abstraction vs Abstract Class

Abstract classes are classes which promote reuse of commonality between classes, but which themselves cannot directly be instantiated with new() - abstract classes must be subclassed, and only concrete (non abstract) subclasses may be instantiated. Possibly one source of confusion between Abstraction and an abstract class was that in the early days of OO, inheritance was more heavily used to achieve code reuse (e.g. with associated abstract base classes). Nowadays, composition is generally favoured over inheritance, and there are more tools available to achieve abstraction, such as through Interfaces, events / delegates / functions, traits / mixins etc.

Re : Encapsulation vs Information Hiding

The meaning of encapsulation appears to have evolved over time, and in recent times, encapsulation can commonly also used in a more general sense when determining which methods, fields, properties, events etc to bundle into a class.

Quoting Wikipedia:

In the more concrete setting of an object-oriented programming language, the notion is used to mean either an information hiding mechanism, a bundling mechanism, or the combination of the two.

For example, in the statement

I've encapsulated the data access code into its own class

.. the interpretation of encapsulation is roughly equivalent to the Separation of Concerns or the Single Responsibility Principal (the "S" in SOLID), and could arguably be used as a synonym for refactoring.

[1] Once you've seen Booch's encapsulation cat picture you'll never be able to forget encapsulation - p46 of Object Oriented Analysis and Design with Applications, 2nd Ed

How do I return a proper success/error message for JQuery .ajax() using PHP?

Some people recommend using HTTP status codes, but I rather despise that practice. e.g. If you're doing a search engine and the provided keywords have no results, the suggestion would be to return a 404 error.

However, I consider that wrong. HTTP status codes apply to the actual browser<->server connection. Everything about the connect went perfectly. The browser made a request, the server invoked your handler script. The script returned 'no rows'. Nothing in that signifies "404 page not found" - the page WAS found.

Instead, I favor divorcing the HTTP layer from the status of your server-side operations. Instead of simply returning some text in a json string, I always return a JSON data structure which encapsulates request status and request results.

e.g. in PHP you'd have

$results = array(
   'error' => false,
   'error_msg' => 'Everything A-OK',
   'data' => array(....results of request here ...)
echo json_encode($results);

Then in your client-side code you'd have

if (!data.error) {
   ... got data, do something with it ...
} else {
   ... invoke error handler ...

In Spring MVC, how can I set the mime type header when using @ResponseBody

Register org.springframework.http.converter.json.MappingJacksonHttpMessageConverter as the message converter and return the object directly from the method.

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
  <property name="webBindingInitializer">
    <bean class=""/>
  <property name="messageConverters">
      <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"/>

and the controller:

@RequestMapping(method=RequestMethod.GET, value="foo/bar")
public @ResponseBody Object fooBar(){
    return myService.getActualObject();

This requires the dependency org.springframework:spring-webmvc.

Redirecting output to $null in PowerShell, but ensuring the variable remains set

I'd prefer this way to redirect standard output (native PowerShell)...

($foo = someFunction) | out-null

But this works too:

($foo = someFunction) > $null

To redirect just standard error after defining $foo with result of "someFunction", do

($foo = someFunction) 2> $null

This is effectively the same as mentioned above.

Or to redirect any standard error messages from "someFunction" and then defining $foo with the result:

$foo = (someFunction 2> $null)

To redirect both you have a few options:

2>&1 | out-null

Swift performSelector:withObject:afterDelay: is unavailable

Swift is statically typed so the performSelector: methods are to fall by the wayside.

Instead, use GCD to dispatch a suitable block to the relevant queue — in this case it'll presumably be the main queue since it looks like you're doing UIKit work.

EDIT: the relevant performSelector: is also notably missing from the Swift version of the NSRunLoop documentation ("1 Objective-C symbol hidden") so you can't jump straight in with that. With that and its absence from the Swiftified NSObject I'd argue it's pretty clear what Apple is thinking here.

Extracting substrings in Go

WARNING: operating on strings alone will only work with ASCII and will count wrong when input is a non-ASCII UTF-8 encoded character, and will probably even corrupt characters since it cuts multibyte chars mid-sequence.

Here's a UTF-8-aware version:

// NOTE: this isn't multi-Unicode-codepoint aware, like specifying skintone or
//       gender of an emoji:
func substr(input string, start int, length int) string {
    asRunes := []rune(input)
    if start >= len(asRunes) {
        return ""
    if start+length > len(asRunes) {
        length = len(asRunes) - start
    return string(asRunes[start : start+length])

ASP.NET 4.5 has not been registered on the Web server

For windows 10 with below error: Configuring Web http://localhost:64886/ for ASP.NET 4.5 failed. You must manually configure this site for ASP.NET 4.5 in order for the site to run correctly. ASP.NET 4.0 has not been registered on the Web server. You need to manually configure your Web server for ASP.NET 4.0 in order for your site to run correctly. Solution:

How do I get Maven to use the correct repositories?

By default, Maven will always look in the official Maven repository, which is

When Maven tries to build a project, it will look in your local repository (by default ~/.m2/repository but you can configure it by changing the <localRepository> value in your ~/.m2/settings.xml) to find any dependency, plugin or report defined in your pom.xml. If the adequate artifact is not found in your local repository, it will look in all external repositories configured, starting with the default one,

You can configure Maven to avoid this default repository by setting a mirror in your settings.xml file:

        <name>Our mirror for Maven repository</name>

This way, instead of contacting, Maven will contact your entreprise repository (http://the/server in this example).

If you want to add another repository, you can define a new one in your settings.xml file:


You can see the complete settings.xml model here.

Concerning the clean process, you can ask Maven to run it offline. In this case, Maven will not try to reach any external repositories:

mvn -o clean 

Visual Studio Code Search and Replace with Regular Expressions

Make sure Match Case is selected with Use Regular Expression so this matches. [A-Z]* If match case is not selected, this matches all letters.

What is the main difference between Collection and Collections in Java?

Collection is a base interface for most collection classes (it is the root interface of java collection framework) Collections is a utility class

Collections class is a utility class having static methods It implements Polymorphic algorithms which operate on collections.

How to display all methods of an object?

You can use Object.getOwnPropertyNames() to get all properties that belong to an object, whether enumerable or not. For example:

//-> ["E", "LN10", "LN2", "LOG2E", "LOG10E", "PI", ...etc ]

You can then use filter() to obtain only the methods:

console.log(Object.getOwnPropertyNames(Math).filter(function (p) {
    return typeof Math[p] === 'function';
//-> ["random", "abs", "acos", "asin", "atan", "ceil", "cos", "exp", ...etc ]

In ES3 browsers (IE 8 and lower), the properties of built-in objects aren't enumerable. Objects like window and document aren't built-in, they're defined by the browser and most likely enumerable by design.

From ECMA-262 Edition 3:

Global Object
There is a unique global object (15.1), which is created before control enters any execution context. Initially the global object has the following properties:

• Built-in objects such as Math, String, Date, parseInt, etc. These have attributes { DontEnum }.
• Additional host defined properties. This may include a property whose value is the global object itself; for example, in the HTML document object model the window property of the global object is the global object itself.

As control enters execution contexts, and as ECMAScript code is executed, additional properties may be added to the global object and the initial properties may be changed.

I should point out that this means those objects aren't enumerable properties of the Global object. If you look through the rest of the specification document, you will see most of the built-in properties and methods of these objects have the { DontEnum } attribute set on them.

Update: a fellow SO user, CMS, brought an IE bug regarding { DontEnum } to my attention.

Instead of checking the DontEnum attribute, [Microsoft] JScript will skip over any property in any object where there is a same-named property in the object's prototype chain that has the attribute DontEnum.

In short, beware when naming your object properties. If there is a built-in prototype property or method with the same name then IE will skip over it when using a loop.

@Directive vs @Component in Angular


Components are the most basic UI building block of an Angular app. An Angular app contains a tree of Angular components. Our application in Angular is built on a component tree. Every component should have its template, styling, life cycle, selector, etc. So, every component has its structure You can treat them as an apart standalone small web application with own template and logic and a possibility to communicate and be used together with other components.

Sample .ts file for Component:

import { Component } from '@angular/core';

    // component attributes
    selector: 'app-training',
    templateUrl: './app-training.component.html',
    styleUrls: ['./app-training.component.less']

export class AppTrainingComponent {
    title = 'my-app-training';

and its ./app.component.html template view:

Hello {{title}}

Then you can render AppTrainingComponent template with its logic in other components (after adding it into module)


and the result will be


as AppTrainingComponent was rendered here

See more about Components


Directive changes the appearance or behavior of an existing DOM element. For example [ngStyle] is a directive. Directives can extend components (can be used inside them) but they don't build a whole application. Let's say they just support components. They don't have its own template (but of course, you can manipulate template with them).

Sample directive:

  selector: '[appHighlight]'
export class HighlightDirective {

  constructor(private el: ElementRef) { }

  @Input('appHighlight') highlightColor: string;

  @HostListener('mouseenter') onMouseEnter() {
    this.highlight(this.highlightColor || 'red');

  private highlight(color: string) { = color;

And its usage:

<p [appHighlight]="color" [otherPar]="someValue">Highlight me!</p>

See more about directives

Read a XML (from a string) and get some fields - Problems reading XML

I used the System.Xml.Linq.XElement for the purpose. Just check code below for reading the value of first child node of the xml(not the root node).

        string textXml = "<xmlroot><firstchild>value of first child</firstchild>........</xmlroot>";
        XElement xmlroot = XElement.Parse(textXml);
        string firstNodeContent = ((System.Xml.Linq.XElement)(xmlroot.FirstNode)).Value;

How do I enable TODO/FIXME/XXX task tags in Eclipse?

There are apparently distributions or custom builds in which the ability to set Task Tags for non-Java files is not present. This post mentions that ColdFusion Builder (built on Eclipse) does not let you set non-Java Task Tags, but the beta version of CF Builder 2 does. (I know the OP wasn't using CF Builder, but I am, and I was wondering about this question myself ... because he didn't see the ability to set non-Java tags, I thought others might be in the same position.)

What's the simplest way to extend a numpy array in 2 dimensions?

The shortest in terms of lines of code i can think of is for the first question.

>>> import numpy as np
>>> p = np.array([[1,2],[3,4]])

>>> p = np.append(p, [[5,6]], 0)
>>> p = np.append(p, [[7],[8],[9]],1)

>>> p
array([[1, 2, 7],
   [3, 4, 8],
   [5, 6, 9]])

And the for the second question

    p = np.array(range(20))
>>> p.shape = (4,5)
>>> p
array([[ 0,  1,  2,  3,  4],
       [ 5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14],
       [15, 16, 17, 18, 19]])
>>> n = 2
>>> p = np.append(p[:n],p[n+1:],0)
>>> p = np.append(p[...,:n],p[...,n+1:],1)
>>> p
array([[ 0,  1,  3,  4],
       [ 5,  6,  8,  9],
       [15, 16, 18, 19]])

Create a simple HTTP server with Java?

I wrote a tutorial explaining how to write a simple HTTP server a while back in Java. Explains what the code is doing and why the server is written that way as the tutorial progresses. Might be useful

Best Practice to Organize Javascript Library & CSS Folder Structure

          bootstrap/--------------Libraries can have js/css/images------------
     common/--------------------common section will have application level resources             


This is how I organized my application's static resources.

Extract Google Drive zip from Google colab notebook

Instead of GetContentString(), use GetContentFile() instead. It will save the file instead of returning the string.


Then you can unzip it later with unzip.

Sharepoint: How do I filter a document library view to show the contents of a subfolder?

Have a look at the content by type web part - - probably the most flexible viewing web part.

How to remove the default arrow icon from a dropdown list (select element)?

padding: 11px 50px 11px 10px;
background: rgba(255,255,255,1);
border-radius: 7px;
-webkit-border-radius: 7px;
-moz-border-radius: 7px;
border: 0;
-webkit-appearance: none;
-moz-appearance: none;
appearance: none;
color: #8ba2d4;


c++ parse int from string

You can use boost::lexical_cast:

#include <iostream>
#include <boost/lexical_cast.hpp>

int main( int argc, char* argv[] ){
std::string s1 = "10";
std::string s2 = "abc";
int i;

   try   {
      i = boost::lexical_cast<int>( s1 );
   catch( boost::bad_lexical_cast & e ){
      std::cout << "Exception caught : " << e.what() << std::endl;

   try   {
      i = boost::lexical_cast<int>( s2 );
   catch( boost::bad_lexical_cast & e ){
      std::cout << "Exception caught : " << e.what() << std::endl;

   return 0;

Angular window resize event

Assuming that < 600px means mobile to you, you can use this observable and subscribe to it:

First we need the current window size. So we create an observable which only emits a single value: the current window size.

initial$ = Observable.of(window.innerWidth > 599 ? false : true);

Then we need to create another observable, so that we know when the window size was changed. For this we can use the "fromEvent" operator. To learn more about rxjs`s operators please visit: rxjs

resize$ = Observable.fromEvent(window, 'resize').map((event: any) => {
  return > 599 ? false : true;

Merg these two streams to receive our observable:

mobile$ = Observable.merge(this.resize$, this.initial$).distinctUntilChanged();

Now you can subscribe to it like this:

mobile$.subscribe((event) => { console.log(event); });

Remember to unsubscribe :)

In R, dealing with Error: ggplot2 doesn't know how to deal with data of class numeric

The error happens because of you are trying to map a numeric vector to data in geom_errorbar: GVW[1:64,3]. ggplot only works with data.frame.

In general, you shouldn't subset inside ggplot calls. You are doing so because your standard errors are stored in four separate objects. Add them to your original data.frame and you will be able to plot everything in one call.

Here with a dplyr solution to summarise the data and compute the standard error beforehand.

d <- GVW %>% group_by(Genotype,variable) %>%
    summarise(mean = mean(value),se = sd(value) / sqrt(n()))

ggplot(d, aes(x = variable, y = mean, fill = Genotype)) + 
  geom_bar(position = position_dodge(), stat = "identity", 
      colour="black", size=.3) +
  geom_errorbar(aes(ymin = mean - se, ymax = mean + se), 
      size=.3, width=.2, position=position_dodge(.9)) +
  xlab("Time") +
  ylab("Weight [g]") +
  scale_fill_hue(name = "Genotype", breaks = c("KO", "WT"), 
      labels = c("Knock-out", "Wild type")) +
  ggtitle("Effect of genotype on weight-gain") +
  scale_y_continuous(breaks = 0:20*4) +

Postgres error on insert - ERROR: invalid byte sequence for encoding "UTF8": 0x00

You can first insert data into blob field and then copy to text field with the folloing function

    ref record;
    i integer;
    FOR ref IN SELECT id, blob_field FROM table LOOP

          --  find 0x00 and replace with space    
      i := position(E'\\000'::bytea in ref.blob_field);
      WHILE i > 0 LOOP
        ref.bob_field := set_byte(ref.blob_field, i-1, 20);
        i := position(E'\\000'::bytea in ref.blobl_field);
      END LOOP

    UPDATE table SET field = encode(ref.blob_field, 'escape') WHERE id =;

End; $$ LANGUAGE plpgsql; 


SELECT blob2text();

Select a Column in SQL not in Group By

You can do this with PARTITION and RANK:

select * from
    select MyPK, fmgcms_cpeclaimid, createdon,  
        Rank() over (Partition BY fmgcms_cpeclaimid order by createdon DESC) as Rank
    from Filteredfmgcms_claimpaymentestimate 
    where createdon < 'reportstartdate' 
) tmp
where Rank = 1

Is there any sizeof-like method in Java?

There's a class/jar available on that uses Java instrumentation to calculate the size of any object. Here's a link to the description: java.sizeOf

There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key country

In my case, the error occurred because I had not initialized the select list in the controller like this:

viewModel.MySelectList = new List<System.Web.Mvc.SelectListItem>();

As none of the existing answers made this clear to me, I post this. Perhaps it helps anybody.

Select tableview row programmatically

if you want to select some row this will help you

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[someTableView selectRowAtIndexPath:indexPath 

This will also Highlighted the row. Then delegate

 [someTableView.delegate someTableView didSelectRowAtIndexPath:indexPath];

MySQL - Meaning of "PRIMARY KEY", "UNIQUE KEY" and "KEY" when used together while creating a table

Just to add to the other answers, the documentation gives this explanation:

  • KEY is normally a synonym for INDEX. The key attribute PRIMARY KEY can also be specified as just KEY when given in a column definition. This was implemented for compatibility with other database systems.

  • A UNIQUE index creates a constraint such that all values in the index must be distinct. An error occurs if you try to add a new row with a key value that matches an existing row. For all engines, a UNIQUE index permits multiple NULL values for columns that can contain NULL.

  • A PRIMARY KEY is a unique index where all key columns must be defined as NOT NULL. If they are not explicitly declared as NOT NULL, MySQL declares them so implicitly (and silently). A table can have only one PRIMARY KEY. The name of a PRIMARY KEY is always PRIMARY, which thus cannot be used as the name for any other kind of index.

MySQL my.ini location

Start MySQL Workbench, then Server -> Options File and look at bottom of the window; it will say something like "Configuration File: C:\ProgramData\MySQL\MySQL Server 5.6\my.ini"

(And note the subtle difference between "ProgramData" and "Program Files" - easy to gloss over if you're looking for a quick answer.)

How do I convert a list of ascii values to a string in python?

You are probably looking for 'chr()':

>>> L = [104, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100]
>>> ''.join(chr(i) for i in L)
'hello, world'

Purge Kafka Topic

To purge the queue you can delete the topic:

bin/ --zookeeper localhost:2181 --delete --topic test

then re-create it:

bin/ --create --zookeeper localhost:2181 \
    --replication-factor 1 --partitions 1 --topic test

How to load an ImageView by URL in Android?

You'll have to download the image firstly

public static Bitmap loadBitmap(String url) {
    Bitmap bitmap = null;
    InputStream in = null;
    BufferedOutputStream out = null;

    try {
        in = new BufferedInputStream(new URL(url).openStream(), IO_BUFFER_SIZE);

        final ByteArrayOutputStream dataStream = new ByteArrayOutputStream();
        out = new BufferedOutputStream(dataStream, IO_BUFFER_SIZE);
        copy(in, out);

        final byte[] data = dataStream.toByteArray();
        BitmapFactory.Options options = new BitmapFactory.Options();
        //options.inSampleSize = 1;

        bitmap = BitmapFactory.decodeByteArray(data, 0, data.length,options);
    } catch (IOException e) {
        Log.e(TAG, "Could not load Bitmap from: " + url);
    } finally {

    return bitmap;

Then use the Imageview.setImageBitmap to set bitmap into the ImageView

Create a data.frame with m columns and 2 rows

For completeness:

Along the lines of Chase's answer, I usually use to coerce the matrix to a data.frame:

m <-, ncol = 30, nrow = 2))

EDIT: speed test data.frame vs.

system.time(replicate(10000, data.frame(matrix(0, ncol = 30, nrow = 2))))
   user  system elapsed 
  8.005   0.108   8.165 

system.time(replicate(10000,, ncol = 30, nrow = 2))))
   user  system elapsed 
  3.759   0.048   3.802 

Yes, it appears to be faster (by about 2 times).

Can I run CUDA on Intel's integrated graphics processor?

If you're interested in learning a language which supports massive parallelism better go for OpenCL since you don't have an NVIDIA GPU. You can run OpenCL on Intel CPUs, but at best you can learn to program SIMDs. Optimization on CPU and GPU are different. I really don't think you can use Intel card for GPGPU.

How to open an external file from HTML

Your first idea used to be the way but I've also noticed issues doing this using Firefox, try a straight http:// to the file - href='http://server/directory/file.xlsx'

How to implement a SQL like 'LIKE' operator in java?

You could turn '%string%' to contains(), 'string%' to startsWith() and '%string"' to endsWith().

You should also run toLowerCase() on both the string and pattern as LIKE is case-insenstive.

Not sure how you'd handle '%string%other%' except with a Regular Expression though.

If you're using Regular Expressions:

How to make <div> fill <td> height

This questions is already answered here. Just put height: 100% in both the div and the container td.

How to check a radio button with jQuery?

Yes, it worked for me like a way:

$("#radio_1").attr('checked', 'checked');

Passing arguments to JavaScript function from code-behind

Response.Write("<scrip" + "t>test(" + x + "," + y + ");</script>");

breaking up the script keyword because VStudio / compiler doesn't like it

How to select a node of treeview programmatically in c#?

Apologies for my previously mixed up answer.

Here is how to do:

myTreeView.SelectedNode = myTreeNode;


I have tested the code below and it works:

public partial class Form1 : Form
    public Form1()

    private void Form1_Load(object sender, EventArgs e)
        treeView1.Nodes.Add("1", "1");
        treeView1.Nodes.Add("2", "2");
        treeView1.Nodes[0].Nodes.Add("1-1", "1-1");
        TreeNode treeNode = treeView1.Nodes[0].Nodes.Add("1-2", "1-3");
        treeView1.SelectedNode = treeNode;


How do I get the full url of the page I am on in C#

I usually use Request.Url.ToString() to get the full url (including querystring), no concatenation required.

How do I force make/GCC to show me the commands?

Since GNU Make version 4.0, the --trace argument is a nice way to tell what and why a makefile do, outputing lines like:

makefile:8: target 'foo.o' does not exist


makefile:12: update target 'foo' due to: bar

TypeError: 'str' object is not callable (Python)

You can get this error if you have variable str and trying to call str() function.

Binding List<T> to DataGridView in WinForm

Yes, it is possible to do with out rebinding by implementing INotifyPropertyChanged Interface.

Pretty Simple example is available here,

Webdriver findElements By xpath

Your questions:

Q 1.) I would like to know why it returns all the texts that following the div?
It should not and I think in will not. It returns all div with 'id' attribute value equal 'containter' (and all children of this). But you are printing the results with ele.getText() Where getText will return all text content of all children of your result.

Get the visible (i.e. not hidden by CSS) innerText of this element, including sub-elements, without any leading or trailing whitespace.
The innerText of this element.

Q 2.) how should I modify the code so it just return first or first few nodes that follow the parent note
This is not really clear what you are looking for. Example:

<p1> <div/> </p1 <p2/> 

The following to parent of the div is p2. This would be:


or shorter


If you are only looking for the first one extent the expression with an "predicate" (e.g [1] - for the first one. or [position() &lt; 4]for the first three)

If your are looking for the first child of the first div:


If there is only one div with id an you are looking for the first child:


and so on.

How to get the timezone offset in GMT(Like GMT+7:00) from android device?

This is how Google recommends getting TimezoneOffset.

Calendar calendar = Calendar.getInstance(Locale.getDefault());
int offset = -(calendar.get(Calendar.ZONE_OFFSET) + calendar.get(Calendar.DST_OFFSET)) / (60 * 1000)

Tricks to manage the available memory in an R session

I really appreciate some of the answers above, following @hadley and @Dirk that suggest closing R and issuing source and using command line I come up with a solution that worked very well for me. I had to deal with hundreds of mass spectras, each occupies around 20 Mb of memory so I used two R scripts, as follows:

First a wrapper:

#!/usr/bin/Rscript --vanilla --default-packages=utils

for(l in 1:length(fdir)) {

   for(k in 1:length(fds)) {
     system(paste("Rscript runConsensus.r", l, k))

with this script I basically control what my main script do runConsensus.r, and I write the data answer for the output. With this, each time the wrapper calls the script it seems the R is reopened and the memory is freed.

Hope it helps.

Remove element from JSON Object

To iterate through the keys of an object, use a for .. in loop:

for (var key in json_obj) {
    if (json_obj.hasOwnProperty(key)) {
        // do something with `key'

To test all elements for empty children, you can use a recursive approach: iterate through all elements and recursively test their children too.

Removing a property of an object can be done by using the delete keyword:

var someObj = {
    "one": 123,
    "two": 345
var key = "one";
delete someObj[key];
console.log(someObj); // prints { "two": 345 }


A keyboard shortcut to comment/uncomment the select text in Android Studio

At least in Android Studio 2.2.3 with default key mapping, to comment or uncomment a select text, same hotkeys are used as Toggle. Using the hotkeys changes the state from comment to uncomment, and next time Uncomment to comment on next and vice versa.

1. Comment / uncomment a block of code

Comment sample: /* --- Code block ---- */

Hotkey: Ctrl + Shift + "/"

Using the same key combinations again will "toggle" commenting or uncommenting the selection.

2. Comment / uncomment a line of code

Comment sample: // -- Code ---

Hotkey: Ctrl + "/"

Using the same key combinations again will "toggle" commenting or uncommenting the selection.

Note: Key mapping can be changed to different schemes like eclipse, visual studio... or to the custom hotkeys in File -> Settings -> Keymap

Call Stored Procedure within Create Trigger in SQL Server



ALTER TRIGGER [dbo].[RA2Newsletter] 
   ON  [dbo].[Reiseagent] 
    @rAgent_Name nvarchar(50),
    @rAgent_Email nvarchar(50),
    @rAgent_IP nvarchar(50),
    @hotelID int,
    @retval int


    -- Insert statements for trigger here
    Select @rAgent_Name=rAgent_Name,@rAgent_Email=rAgent_Email,@rAgent_IP=rAgent_IP,@hotelID=hotelID  From Inserted
    EXEC insert2Newsletter '','',@rAgent_Name,@rAgent_Email,@rAgent_IP,@hotelID,'RA', @retval


Pass a datetime from javascript to c# (Controller)

There is a toJSON() method in javascript returns a string representation of the Date object. toJSON() is IE8+ and toISOString() is IE9+. Both results in YYYY-MM-DDTHH:mm:ss.sssZ format.

var date = new Date();    
           type: "POST",
           url: "/Group/Refresh",
           contentType: "application/json; charset=utf-8",
           data: "{ 'MyDate': " + date.toJSON() + " }",
           success: function (result) {
               //do something
           error: function (req, status, error) {

jQuery.each - Getting li elements inside an ul

$(function() {
    $('.phrase .items').each(function(i, items_list){
        var myText = "";

        $(items_list).find('li').each(function(j, li){



How can I get my webapp's base URL in ASP.NET MVC?

For MVC 4:

String.Format("{0}://{1}{2}", Url.Request.RequestUri.Scheme, Url.Request.RequestUri.Authority, ControllerContext.Configuration.VirtualPathRoot);

Chrome Extension - Get DOM content

For those who tried gkalpak answer and it did not work,

be aware that chrome will add the content script to a needed page only when your extension enabled during chrome launch and also a good idea restart browser after making these changes

Including non-Python files with

Step 1: create a file in the same folder with

Step 2: include the relative path to the files you want to add in

include README.rst
include docs/*.txt
include funniest/data.json

Step 3: set include_package_data=True in the setup() function to copy these files to site-package

Reference is here.