Programs & Examples On #Msnpsharp

MSNPSharp is a .net library that implements the MSN protocol. It's the continuation of project DotMSN ended in 2006.

jQuery UI tabs. How to select a tab based on its id not based on index

It may have side effects if there are other listeners, and it doesn't feel as nice as interacting through the plugins API -- but it gives a less verbose code if you just "click" the tab, rather than count it's index and set it active afterwards, and it's pretty intuitive what's going on. Also it wont fail if the ui-guys decide to rename the option again.

$('#tabs a[href="#tabtwo"]').click();

It's intriguing, though, that the ui tabs code has a meta-function (_getIndex) with the comment:

"meta-function to give users option to provide a href string instead of a numerical index"

but does not use it when setting the active option, only when calling enable, disable and load.

pandas: filter rows of DataFrame with operator chaining

I offer this for additional examples. This is the same answer as

I'll add other edits to make this post more useful.

query was made for exactly this purpose. Consider the dataframe df

import pandas as pd
import numpy as np

df = pd.DataFrame(
    np.random.randint(10, size=(10, 5)),


   A  B  C  D  E
0  0  2  7  3  8
1  7  0  6  8  6
2  0  2  0  4  9
3  7  3  2  4  3
4  3  6  7  7  4
5  5  3  7  5  9
6  8  7  6  4  7
7  6  2  6  6  5
8  2  8  7  5  8
9  4  7  6  1  5

Let's use query to filter all rows where D > B

df.query('D > B')

   A  B  C  D  E
0  0  2  7  3  8
1  7  0  6  8  6
2  0  2  0  4  9
3  7  3  2  4  3
4  3  6  7  7  4
5  5  3  7  5  9
7  6  2  6  6  5

Which we chain

df.query('D > B').query('C > B')
# equivalent to
# df.query('D > B and C > B')
# but defeats the purpose of demonstrating chaining

   A  B  C  D  E
0  0  2  7  3  8
1  7  0  6  8  6
4  3  6  7  7  4
5  5  3  7  5  9
7  6  2  6  6  5

How do I delete specific characters from a particular String in Java?

You can use replaceAll() method :

String.replaceAll(",", "");
String.replaceAll("\\.", "");
String.replaceAll("\\(", "");


java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Integer in java 1.6

The number of results can (theoretically) be greater than the range of an integer. I would refactor the code and work with the returned long value instead.

How can I use JavaScript in Java?

Rhino is what you are looking for.

Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically embedded into Java applications to provide scripting to end users.

Update: Now Nashorn, which is more performant JavaScript Engine for Java, is available with jdk8.

How to capture the android device screen content?

For newer Android platforms, one can execute a system utility screencap in /system/bin to get the screenshot without root permission. You can try /system/bin/screencap -h to see how to use it under adb or any shell.

By the way, I think this method is only good for single snapshot. If we want to capture multiple frames for screen play, it will be too slow. I don't know if there exists any other approach for a faster screen capture.

What is the Angular equivalent to an AngularJS $watch?

You can use getter function or get accessor to act as watch on angular 2.

See demo here.

import {Component} from 'angular2/core';

  // Declare the tag name in index.html to where the component attaches
  selector: 'hello-world',

  // Location of the template for this component
  template: `
  <button (click)="OnPushArray1()">Push 1</button>
    I'm array 1 {{ array1 | json }}
  <button (click)="OnPushArray2()">Push 2</button>
    I'm array 2 {{ array2 | json }}
  I'm concatenated {{ concatenatedArray | json }}
    I'm length of two arrays {{ arrayLength | json }}
export class HelloWorld {
    array1: any[] = [];
    array2: any[] = [];

    get concatenatedArray(): any[] {
      return this.array1.concat(this.array2);

    get arrayLength(): number {
      return this.concatenatedArray.length;

    OnPushArray1() {

    OnPushArray2() {

Declare global variables in Visual Studio 2010 and VB.NET

The various answers in this blog seem to be defined by SE's who promote strict adherence to the usual rules of object-oriented programming (use a Public Class with public shared (aka static), and fully-qualified class references, or SE's who promote using the backward-compatibility feature (Module) for which the compiler obviously needs to do the same thing to make it work.

As a SE with 30+ years of experience, I would propose the following guidelines:

  1. If you are writing all new code (not attempting to convert a legacy app) that you avoid using these forms altogether except in the rare instance that you really DO need to have a static variable because they can cause terrible consequences (and really hard-to-find bugs). (Multithread and multiprocessing code requires semaphores around static variables...)

  2. If you are modifying a small application that already has a few global variables, then formulate them so they are not obscured by Modules, that is, use the standard rules of object-oriented programming to re-create them as public static and access them by full qualification so others can figure out what is going on.

  3. If you have a huge legacy application with dozens or hundreds of global variables, by all means, use Modules to define them. There is no reason to waste time when getting the application working, because you are probably already behind the 8-ball in time spent on Properties, etc.

How to load data to hive from HDFS without removing the source file?

from your question I assume that you already have your data in hdfs. So you don't need to LOAD DATA, which moves the files to the default hive location /user/hive/warehouse. You can simply define the table using the externalkeyword, which leaves the files in place, but creates the table definition in the hive metastore. See here: Create Table DDL eg.:

create external table table_name (
  id int,
  myfields string
location '/my/location/in/hdfs';

Please note that the format you use might differ from the default (as mentioned by JigneshRawal in the comments). You can use your own delimiter, for example when using Sqoop:

row format delimited fields terminated by ','

Why does Boolean.ToString output "True" and not "true"

It's simple code to convert that to all lower case.

Not so simple to convert "true" back to "True", however.


is what I use for xml output.

Assign value from successful promise resolve to external variable

The then() method returns a Promise. It takes two arguments, both are callback functions for the success and failure cases of the Promise. the promise object itself doesn't give you the resolved data directly, the interface of this object only provides the data via callbacks supplied. So, you have to do this like this:

getFeed().then(function(data) { vm.feed = data;});

The then() function returns the promise with a resolved value of the previous then() callback, allowing you the pass the value to subsequent callbacks:

promiseB = promiseA.then(function(result) {
  return result + 1;

// promiseB will be resolved immediately after promiseA is resolved
// and its value will be the result of promiseA incremented by 1

How to set a dropdownlist item as selected in ASP.NET?

You can use the FindByValue method to search the DropDownList for an Item with a Value matching the parameter.

dropdownlist.Items.FindByValue(value).Selected = true;

Alternatively you can use the FindByText method to search the DropDownList for an Item with Text matching the parameter.

Before using the FindByValue method, don't forget to reset the DropDownList so that no items are selected by using the ClearSelection() method. It clears out the list selection and sets the Selected property of all items to false. Otherwise you will get the following exception.

"Cannot have multiple items selected in a DropDownList"

How to refer to relative paths of resources when working with a code repository

import os
cwd = os.getcwd()
path = os.path.join(cwd, "my_file")
f = open(path)

You also try to normalize your cwd using os.path.abspath(os.getcwd()). More info here.

When to favor ng-if vs. ng-show/ng-hide?

If you use ng-show or ng-hide the content (eg. thumbnails from server) will be loaded irrespective of the value of expression but will be displayed based on the value of the expression.

If you use ng-if the content will be loaded only if the expression of the ng-if evaluates to truthy.

Using ng-if is a good idea in a situation where you are going to load data or images from the server and show those only depending on users interaction. This way your page load will not be blocked by unnecessary nw intensive tasks.

How to log out user from web site using BASIC authentication?

Have the user click on a link to https://log:[email protected]/. That will overwrite existing credentials with invalid ones; logging them out.

ORA-00918: column ambiguously defined in SELECT *

You have multiple columns named the same thing in your inner query, so the error is raised in the outer query. If you get rid of the outer query, it should run, although still be confusing:

    INNER JOIN people ON = coaches.person_id
    INNER JOIN users ON coaches.person_id = users.person_id
    LEFT OUTER JOIN organizations_users ON organizations_users.user_id =
    rownum <= 25

It would be much better (for readability and performance both) to specify exactly what fields you need from each of the tables instead of selecting them all anyways. Then if you really need two fields called the same thing from different tables, use column aliases to differentiate between them.

Javascript Confirm popup Yes, No button instead of OK and Cancel

You can also use . It's very simple and easy to use. Just include jquery common library and one more file only:

<script src="" type="text/javascript"></script>
<script src=""></script>
<link rel="stylesheet" href="" type="text/css" />
<script src="jquery.easy-confirm-dialog.js"></script>

Live-stream video from one android phone to another over WiFi

If you do not need the recording and playback functionality in your app, using off-the-shelf streaming app and player is a reasonable choice.

If you do need them to be in your app, however, you will have to look into MediaRecorder API (for the server/camera app) and MediaPlayer (for client/player app).

Quick sample code for the server:

// this is your network socket
ParcelFileDescriptor pfd = ParcelFileDescriptor.fromSocket(socket);
mCamera = getCameraInstance();
mMediaRecorder = new MediaRecorder();
// this is the unofficially supported MPEG2TS format, suitable for streaming (Android 3.0+)

On the player side it is a bit tricky, you could try this:

// this is your network socket, connected to the server
ParcelFileDescriptor pfd = ParcelFileDescriptor.fromSocket(socket);
mMediaPlayer = new MediaPlayer();

Unfortunately mediaplayer tends to not like this, so you have a couple of options: either (a) save data from socket to file and (after you have a bit of data) play with mediaplayer from file, or (b) make a tiny http proxy that runs locally and can accept mediaplayer's GET request, reply with HTTP headers, and then copy data from the remote server to it. For (a) you would create the mediaplayer with a file path or file url, for (b) give it a http url pointing to your proxy.

See also:

Stream live video from phone to phone using socket fd

MediaPlayer stutters at start of mp3 playback

How to use JavaScript source maps (.map files)?

Just wanted to focus on the last part of the question; How source map files are created? by listing the build tools I know that can create source maps.

  1. Grunt: using plugin grunt-contrib-uglify
  2. Gulp: using plugin gulp-uglify
  3. Google closure: using parameter --create_source_map

Allowing Java to use an untrusted certificate for SSL/HTTPS connection

Here is some relevant code:

// Create a trust manager that does not validate certificate chains
TrustManager[] trustAllCerts = new TrustManager[]{
    new X509TrustManager() {
        public[] getAcceptedIssuers() {
            return null;
        public void checkClientTrusted(
  [] certs, String authType) {
        public void checkServerTrusted(
  [] certs, String authType) {

// Install the all-trusting trust manager
try {
    SSLContext sc = SSLContext.getInstance("SSL");
    sc.init(null, trustAllCerts, new;
} catch (Exception e) {

// Now you can access an https URL without having the certificate in the truststore
try {
    URL url = new URL("https://hostname/index.html");
} catch (MalformedURLException e) {

This will completely disable SSL checking—just don't learn exception handling from such code!

To do what you want, you would have to implement a check in your TrustManager that prompts the user.

How to pass a callback as a parameter into another function

Yes of course, function are objects and can be passed, but of course you must declare it:

function firstFunction(){
    //some code
    var callbackfunction = function(data){
       //do something with the data returned from the ajax request
    //a callback function is written for $.post() to execute

an interesting thing is that your callback function has also access to every variable you might have declared inside firstFunction() (variables in javascript have local scope).

Using ZXing to create an Android barcode scanning app

Using Zxing this way requires a user to also install the barcode scanner app, which isn't ideal. What you probably want is to bundle Zxing into your app directly.

I highly recommend using this library:

It takes all the crazy build issues you're going to run into trying to integrate Xzing or Zbar directly. It uses those libraries under the covers, but wraps them in a very simple to use API.

How to link to specific line number on github

For a line in a pull request.
90 <- PR number
ce6bf647d5a531e54ef0502c7fe799de <- MD5 has of file name from repo root
R <- Which side of the diff to reference (merge-base or head). Can be L or R.
27 <- Line number

This will take you to a line as long as L and R are correct. I am not sure if there is a way to visit L OR R. I.e If the PR adds a line you must use R. If it removes a line you must use L.

From: Generate line pointer URL into Github Pull Request

How do I apply the for-each loop to every character in a String?

String s = "xyz";
for(int i = 0; i < s.length(); i++)
   char c = s.charAt(i);


Disable submit button ONLY after submit

I put this in my global code to work on all submit buttons:

$("input[type='submit']").on("click", function (e) {
    $(this).attr("disabled", true);

CSS vertical-align: text-bottom;

if your text doesn't spill over two rows then you can do line-height: ; in your CSS, the more line-height you give, the lower on the container it will hold.

Converting byte array to string in javascript

I had some decrypted byte arrays with padding characters and other stuff I didn't need, so I did this (probably not perfect, but it works for my limited use)

var junk = String.fromCharCode.apply(null, res).split('').map(char => char.charCodeAt(0) <= 127 && char.charCodeAt(0) >= 32 ? char : '').join('');

How can you create multiple cursors in Visual Studio Code

I had problem with ALT key, fix is to change alt+click as a Gnome hotkey which clobbers multi-cursor select in VSCode, to super+click by running:

gsettings set org.gnome.desktop.wm.preferences mouse-button-modifier "<Super>"   


Convert Pandas column containing NaNs to dtype `int`

As of Pandas 1.0.0 you can now use pandas.NA values. This does not force integer columns with missing values to be floats.

When reading in your data all you have to do is:

df= pd.read_csv("data.csv", dtype={'id': 'Int64'})  

Notice the 'Int64' is surrounded by quotes and the I is capitalized. This distinguishes Panda's 'Int64' from numpy's int64.

As a side note, this will also work with .astype()

df['id'] = df['id'].astype('Int64')

Documentation here

Redirect to external URL with return in laravel

You should be able to redirect to the url like this

return Redirect::to($url);

You can read about Redirects in the Laravel docs here.

How to center a <p> element inside a <div> container?

on the p element, add 3 styling rules.

    margin-left:  auto;
    margin-right: auto;
    text-align: center;

How do I join two lists in Java?

Probably not simpler, but intriguing and ugly:

List<String> newList = new ArrayList<String>() { { addAll(listOne); addAll(listTwo); } };

Don't use it in production code... ;)

Replace Div Content onclick

A simple addClass and removeClass will do the trick on what you need..

$('#change').on('click', function() { 
  $('div').each(function() { 
    if($(this).hasClass('active')) { 
    } else { 


Seee fiddle

I recommend you to learn jquery first before using.

Error "library not found for" after putting application in AdMob

Select your Target, go to "Build Phases" in "Link Binary With Libraries" remove ".a" file of that library. Clean and Build.

What is the difference between '/' and '//' when used for division?

In Python 3.x, 5 / 2 will return 2.5 and 5 // 2 will return 2. The former is floating point division, and the latter is floor division, sometimes also called integer division.

In Python 2.2 or later in the 2.x line, there is no difference for integers unless you perform a from __future__ import division, which causes Python 2.x to adopt the 3.x behavior.

Regardless of the future import, 5.0 // 2 will return 2.0 since that's the floor division result of the operation.

You can find a detailed description at

There has been an error processing your request, Error log record number

Clear your cache and your website will be work well.

Ruby capitalize every word first letter

try this:

puts 'one TWO three foUR'' ')

#=> One Two Three Four


puts 'one TWO three foUR'*' '

How to get file name when user select a file via <input type="file" />?

You can get the file name, but you cannot get the full client file-system path.

Try to access to the value attribute of your file input on the change event.

Most browsers will give you only the file name, but there are exceptions like IE8 which will give you a fake path like: "C:\fakepath\myfile.ext" and older versions (IE <= 6) which actually will give you the full client file-system path (due its lack of security).

document.getElementById('fileInput').onchange = function () {
  alert('Selected file: ' + this.value);

How do you create nested dict in Python?

For arbitrary levels of nestedness:

In [2]: def nested_dict():
   ...:     return collections.defaultdict(nested_dict)

In [3]: a = nested_dict()

In [4]: a
Out[4]: defaultdict(<function __main__.nested_dict>, {})

In [5]: a['a']['b']['c'] = 1

In [6]: a
defaultdict(<function __main__.nested_dict>,
            {'a': defaultdict(<function __main__.nested_dict>,
                         {'b': defaultdict(<function __main__.nested_dict>,
                                      {'c': 1})})})

How can I convert the "arguments" object to an array in JavaScript?

ES6 using rest parameters

If you are able to use ES6 you can use:

Rest Parameters

function sortArgs(...args) {_x000D_
  return args.sort(function (a, b) { return a - b; });_x000D_
document.body.innerHTML = sortArgs(12, 4, 6, 8).toString();

As you can read in the link

The rest parameter syntax allows us to represent an indefinite number of arguments as an array.

If you are curious about the ... syntax, it is called Spread Operator and you can read more here.

ES6 using Array.from()

Using Array.from:

function sortArgs() {_x000D_
  return Array.from(arguments).sort(function (a, b) { return a - b; });_x000D_
document.body.innerHTML = sortArgs(12, 4, 6, 8).toString();

Array.from simply convert Array-like or Iterable objects into Array instances.


You can actually just use Array's slice function on an arguments object, and it will convert it into a standard JavaScript array. You'll just have to reference it manually through Array's prototype:

function sortArgs() {
    var args =;
    return args.sort();

Why does this work? Well, here's an excerpt from the ECMAScript 5 documentation itself:

NOTE: The slice function is intentionally generic; it does not require that its this value be an Array object. Therefore it can be transferred to other kinds of objects for use as a method. Whether the slice function can be applied successfully to a host object is implementation-dependent.

Therefore, slice works on anything that has a length property, which arguments conveniently does.

If Array.prototype.slice is too much of a mouthful for you, you can abbreviate it slightly by using array literals:

var args = [];

However, I tend to feel that the former version is more explicit, so I'd prefer it instead. Abusing the array literal notation feels hacky and looks strange.

How do you properly use WideCharToMultiByte

You use the lpMultiByteStr [out] parameter by creating a new char array. You then pass this char array in to get it filled. You only need to initialize the length of the string + 1 so that you can have a null terminated string after the conversion.

Here are a couple of useful helper functions for you, they show the usage of all parameters.

#include <string>

std::string wstrtostr(const std::wstring &wstr)
    // Convert a Unicode string to an ASCII string
    std::string strTo;
    char *szTo = new char[wstr.length() + 1];
    szTo[wstr.size()] = '\0';
    WideCharToMultiByte(CP_ACP, 0, wstr.c_str(), -1, szTo, (int)wstr.length(), NULL, NULL);
    strTo = szTo;
    delete[] szTo;
    return strTo;

std::wstring strtowstr(const std::string &str)
    // Convert an ASCII string to a Unicode String
    std::wstring wstrTo;
    wchar_t *wszTo = new wchar_t[str.length() + 1];
    wszTo[str.size()] = L'\0';
    MultiByteToWideChar(CP_ACP, 0, str.c_str(), -1, wszTo, (int)str.length());
    wstrTo = wszTo;
    delete[] wszTo;
    return wstrTo;


Anytime in documentation when you see that it has a parameter which is a pointer to a type, and they tell you it is an out variable, you will want to create that type, and then pass in a pointer to it. The function will use that pointer to fill your variable.

So you can understand this better:

//pX is an out parameter, it fills your variable with 10.
void fillXWith10(int *pX)
  *pX = 10;

int main(int argc, char ** argv)
  int X;
  return 0;

What is "Connect Timeout" in sql server connection string?

Gets the time to wait while trying to establish a connection before terminating the attempt and generating an error.

Loading existing .html file with android WebView

ok, that was my very stupid mistake. I post the answer here just in case someone has the same problem.

The correct path for files stored in assets folder is file:///android_asset/* (with no "s" for assets folder which i was always thinking it must have a "s").

And, mWebView.loadUrl("file:///android_asset/myfile.html"); works under all API levels.

I still not figure out why mWebView.loadUrl("file:///android_res/raw/myfile.html"); works only on API level 8. But it doesn't matter now.

NSArray + remove item from array

Remove Object from NSArray with this Method:

-(NSArray *) removeObjectFromArray:(NSArray *) array withIndex:(NSInteger) index {
    NSMutableArray *modifyableArray = [[NSMutableArray alloc] initWithArray:array];
    [modifyableArray removeObjectAtIndex:index];
    return [[NSArray alloc] initWithArray:modifyableArray];

ElasticSearch - Return Unique Values

Elasticsearch 1.1+ has the Cardinality Aggregation which will give you a unique count

Note that it is actually an approximation and accuracy may diminish with high-cardinality datasets, but it's generally pretty accurate in my testing.

You can also tune the accuracy with the precision_threshold parameter. The trade-off, or course, is memory usage.

This graph from the docs shows how a higher precision_threshold leads to much more accurate results.

Relative error vs threshold

python tuple to dict

If there are multiple values for the same key, the following code will append those values to a list corresponding to their key,

d = dict()
for x,y in t:
        d[y] = [x]

What's the difference between ViewData and ViewBag?

Internally ViewBag properties are stored as name/value pairs in the ViewData dictionary.

Note: in most pre-release versions of MVC 3, the ViewBag property was named the ViewModel as noted in this snippet from MVC 3 release notes:

(edited 10-8-12) It was suggested I post the source of this info I posted, here is the source:

MVC 2 controllers support a ViewData property that enables you to pass data to a view template using a late-bound dictionary API. In MVC 3, you can also use somewhat simpler syntax with the ViewBag property to accomplish the same purpose. For example, instead of writing ViewData["Message"]="text", you can write ViewBag.Message="text". You do not need to define any strongly-typed classes to use the ViewBag property. Because it is a dynamic property, you can instead just get or set properties and it will resolve them dynamically at run time. Internally, ViewBag properties are stored as name/value pairs in the ViewData dictionary. (Note: in most pre-release versions of MVC 3, the ViewBag property was named the ViewModel property.)

Search an array for matching attribute

Must be too late now, but the right version would be:

for(var i = 0; i <; i++)
  if([i].food == 'chicken')

ASP.NET MVC View Engine Comparison

My current choice is Razor. It is very clean and easy to read and keeps the view pages very easy to maintain. There is also intellisense support which is really great. ALos, when used with web helpers it is really powerful too.

To provide a simple sample:

@Model namespace.model
<!Doctype html>
<title>Test Razor</title>
<ul class="mainList">
@foreach(var x in ViewData.model)

And there you have it. That is very clean and easy to read. Granted, that's a simple example but even on complex pages and forms it is still very easy to read and understand.

As for the cons? Well so far (I'm new to this) when using some of the helpers for forms there is a lack of support for adding a CSS class reference which is a little annoying.

Thanks Nathj07

MySQL my.cnf performance tuning recommendations

Try starting with the Percona wizard and comparing their recommendations against your current settings one by one. Don't worry there aren't as many applicable settings as you might think.

Update circa 2020: Sorry, this tool reached it's end of life:

Everyone points to key_buffer_size first which you have addressed. With 96GB memory I'd be wary of any tiny default value (likely to be only 96M!).

How to convert a timezone aware string to datetime in Python without dateutil?

There are two issues with the code in the original question: there should not be a : in the timezone and the format string for "timezone as an offset" is lower case %z not upper %Z.

This works for me in Python v3.6

>>> from datetime import datetime
>>> t = datetime.strptime("2012-11-01T04:16:13-0400", "%Y-%m-%dT%H:%M:%S%z")
>>> print(t)
2012-11-01 04:16:13-04:00

Removing duplicates from a String in Java

Code to remove the duplicate characters in a string without using any additional buffer. NOTE: One or two additional variables are fine. An extra array is not:

import java.util.*;
public class Main{
    public static char[] removeDupes(char[] arr){
        if (arr == null || arr.length < 2)
            return arr;
        int len = arr.length;
        int tail = 1;
        for(int x = 1; x < len; x++){
            int y;
            for(y = 0; y < tail; y++){
                if (arr[x] == arr[y]) break;
            if (y == tail){
                arr[tail] = arr[x];
        return Arrays.copyOfRange(arr, 0, tail);

    public static char[] bigArr(int len){
        char[] arr = new char[len];
        Random r = new Random();
        String alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()-=_+[]{}|;:',.<>/?`~";

        for(int x = 0; x < len; x++){
            arr[x] = alphabet.charAt(r.nextInt(alphabet.length()));

        return arr;
    public static void main(String args[]){

        String result = new String(removeDupes(new char[]{'a', 'b', 'c', 'd', 'a'}));
        assert "abcd".equals(result) : "abcda should return abcd but it returns: " + result;

        result = new String(removeDupes(new char[]{'a', 'a', 'a', 'a'}));
        assert "a".equals(result) : "aaaa should return a but it returns: " + result;

        result = new String(removeDupes(new char[]{'a', 'b', 'c', 'a'}));
        assert "abc".equals(result) : "abca should return abc but it returns: " + result;

        result = new String(removeDupes(new char[]{'a', 'a', 'b', 'b'}));
        assert "ab".equals(result) : "aabb should return ab but it returns: " + result;

        result = new String(removeDupes(new char[]{'a'}));
        assert "a".equals(result) : "a should return a but it returns: " + result;

        result = new String(removeDupes(new char[]{'a', 'b', 'b', 'a'}));
        assert "ab".equals(result) : "abba should return ab but it returns: " + result;

        char[] arr = bigArr(5000000);
        long startTime = System.nanoTime();
        System.out.println("2: " + new String(removeDupes(arr)));
        long endTime = System.nanoTime();
        long duration = (endTime - startTime);
        System.out.println("Program took: " + duration + " nanoseconds");
        System.out.println("Program took: " + duration/1000000000 + " seconds");


How to read and talk about the above code:

  1. The method called removeDupes takes an array of primitive char called arr.
  2. arr is returned as an array of primitive characters "by value". The arr passed in is garbage collected at the end of Main's member method removeDupes.
  3. The runtime complexity of this algorithm is O(n) or more specifically O(n+(small constant)) the constant being the unique characters in the entire array of primitive chars.
  4. The copyOfRange does not increase runtime complexity significantly since it only copies a small constant number of items. The char array called arr is not stepped all the way through.
  5. If you pass null into removeDupes, the method returns null.
  6. If you pass an empty array of primitive chars or an array containing one value, that unmodified array is returned.
  7. Method removeDupes goes about as fast as physically possible, fully utilizing the L1 and L2 cache, so Branch redirects are kept to a minimum.
  8. A 2015 standard issue unburdened computer should be able to complete this method with an primitive char array containing 500 million characters between 15 and 25 seconds.

Explain how this code works:

The first part of the array passed in is used as the repository for the unique characters that are ultimately returned. At the beginning of the function the answer is: "the characters between 0 and 1" as between 0 and tail.

We define the variable y outside of the loop because we want to find the first location where the array index that we are looking at has been duplicated in our repository. When a duplicate is found, it breaks out and quits, the y==tail returns false and the repository is not contributed to.

when the index x that we are peeking at is not represented in our repository, then we pull that one and add it to the end of our repository at index tail and increment tail.

At the end, we return the array between the points 0 and tail, which should be smaller or equal to in length to the original array.

Talking points exercise for coder interviews:

Will the program behave differently if you change the y++ to ++y? Why or why not.

Does the array copy at the end represent another 'N' pass through the entire array making runtime complexity O(n*n) instead of O(n) ? Why or why not.

Can you replace the double equals comparing primitive characters with a .equals? Why or why not?

Can this method be changed in order to do the replacements "by reference" instead of as it is now, "by value"? Why or why not?

Can you increase the efficiency of this algorithm by sorting the repository of unique values at the beginning of 'arr'? Under which circumstances would it be more efficient?

Pandas column of lists, create a row for each list element

you can also use pd.concat and pd.melt for this:

>>> objs = [df, pd.DataFrame(df['samples'].tolist())]
>>> pd.concat(objs, axis=1).drop('samples', axis=1)
   subject  trial_num     0     1     2
0        1          1 -0.49 -1.00  0.44
1        1          2 -0.28  1.48  2.01
2        1          3 -0.52 -1.84  0.02
3        2          1  1.23 -1.36 -1.06
4        2          2  0.54  0.18  0.51
5        2          3 -2.18 -0.13 -1.35
>>> pd.melt(_, var_name='sample_num', value_name='sample', 
...         value_vars=[0, 1, 2], id_vars=['subject', 'trial_num'])
    subject  trial_num sample_num  sample
0         1          1          0   -0.49
1         1          2          0   -0.28
2         1          3          0   -0.52
3         2          1          0    1.23
4         2          2          0    0.54
5         2          3          0   -2.18
6         1          1          1   -1.00
7         1          2          1    1.48
8         1          3          1   -1.84
9         2          1          1   -1.36
10        2          2          1    0.18
11        2          3          1   -0.13
12        1          1          2    0.44
13        1          2          2    2.01
14        1          3          2    0.02
15        2          1          2   -1.06
16        2          2          2    0.51
17        2          3          2   -1.35

last, if you need you can sort base on the first the first three columns.

curl usage to get header

You need to add the -i flag to the first command, to include the HTTP header in the output. This is required to print headers.

curl -X HEAD -i

More here:

Calculating Page Table Size

Suppose logical address space is **32 bit so total possible logical entries will be 2^32 and other hand suppose each page size is 4 byte then size of one page is *2^2*2^10=2^12...* now we know that no. of pages in page table is pages=total possible logical address entries/page size so pages=2^32/2^12 =2^20 Now suppose that each entry in page table takes 4 bytes then total size of page table in *physical memory will be=2^2*2^20=2^22=4mb***

How to reverse apply a stash?

You can follow the image i shared to unstash if u accidentally tapped stashing.

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

 mAddTaskButton.setOnClickListener(new View.OnClickListener()

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

How to add dll in c# project

The DLL must be present at all times - as the name indicates, a reference only tells VS that you're trying to use stuff from the DLL. In the project file, VS stores the actual path and file name of the referenced DLL. If you move or delete it, VS is not able to find it anymore.

I usually create a libs folder within my project's folder where I copy DLLs that are not installed to the GAC. Then, I actually add this folder to my project in VS (show hidden files in VS, then right-click and "Include in project"). I then reference the DLLs from the folder, so when checking into source control, the library is also checked in. This makes it much easier when more than one developer will have to change the project.

(Please make sure to set the build type to "none" and "don't copy to output folder" for the DLL in your project.)

PS: I use a German Visual Studio, so the captions I quoted may not exactly match the English version...

Can you issue pull requests from the command line on GitHub?

I've used this tool before- although it seems like there needs to be an issue open first, it is super useful and really streamlines workflow if you use github issue tracking. git open-pull and then a pull request is submitted from whatever branch you are on or select.

EDIT: Looks like you can create issues on the fly, so this tool is a good solution.

Check if a row exists using old mysql_* API

Easiest way to check if a row exists:

$lectureName = mysql_real_escape_string($lectureName);  // SECURITY!
$result = mysql_query("SELECT 1 FROM preditors_assigned WHERE lecture_name='$lectureName' LIMIT 1");
if (mysql_fetch_row($result)) {
    return 'Assigned';
} else {
    return 'Available';

No need to mess with arrays and field names.

What is the difference between the | and || or operators?

By their mathematical definition, OR and AND are binary operators; they verify the LHS and RHS conditions regardless, similarly to | and &.

|| and && alter the properties of the OR and AND operators by stopping them when the LHS condition isn't fulfilled.

How to run python script on terminal (ubuntu)?

First create the file you want, with any editor like vi r gedit. And save with. Py extension.In that the first line should be

!/usr/bin/env python

Importing project into Netbeans

From Netbeans 8.1 - there is an "Import from ZIP" option.

Go to Main Menu -> File -> Import Project -> from ZIP.

Browse your .ZIP file's location via Browse button.

If you have Java project depending on external Libraries, Netbeans will highlight & ask for "Resolving problems" in project, click on resolve, provide location in your file system containing required library files .e.g JARs etc & you will be good to go.

How can I display the users profile pic using the facebook graph api?

The returned data is the binary data of the image type. If you use JavaScript to retrieve the user photo, please get the photo data as blob type in a XMLHttpRequest, and then retrieve the blob URL from the response. For your reference:

 var request = new XMLHttpRequest;
 var photoUri=config.endpoints.graphApiUri + "/v1.0/me/photo/$value";"GET",photoUri);
 request.setRequestHeader("Authorization","Bearer "+token);
 request.responseType = "blob";
 request.onload = function (){
        if(request.readyState == 4 && request.status == 200){
               var image = document.createElement("img");
               var url = window.URL || window.webkitURL;
               var blobUrl = url.createObjectURL(request.response);
               image.src = blobUrl;

How can I install a local gem?

if you download the project file from github or other scm host site, use gem build to build the project first, so you can get a whatever.gem file in current directory. Then gem install it!

How to list files in an android directory?

If you are on Android 10/Q and you did all of the correct things to request access permissions to read external storage and it still doesn't work, it's worth reading this answer:

Android Q (10) ask permission to get access all storage. Scoped storage

I had working code, but me device took it upon itself to update when it was on a network connection (it was usually without a connection.) Once in Android 10, the file access no longer worked. The only easy way to fix it without rewriting the code was to add that extra attribute to the manifest as described. The file access now works as in Android 9 again. YMMV, it probably won't continue to work in future versions.

Logo image and H1 heading on the same line

Just stick the img tag inside the h1 tag as part of the content.

Does Python have an ordered set?

The answer is no, but you can use collections.OrderedDict from the Python standard library with just keys (and values as None) for the same purpose.

Update: As of Python 3.7 (and CPython 3.6), standard dict is guaranteed to preserve order and is more performant than OrderedDict. (For backward compatibility and especially readability, however, you may wish to continue using OrderedDict.)

Here's an example of how to use dict as an ordered set to filter out duplicate items while preserving order, thereby emulating an ordered set. Use the dict class method fromkeys() to create a dict, then simply ask for the keys() back.

>>> keywords = ['foo', 'bar', 'bar', 'foo', 'baz', 'foo']

>>> list(dict.fromkeys(keywords))
['foo', 'bar', 'baz']

Parse RSS with jQuery

Use Google AJAX Feed API unless your RSS data is private. It's fast, of course.

PreparedStatement with Statement.RETURN_GENERATED_KEYS

You can either use the prepareStatement method taking an additional int parameter

PreparedStatement ps = con.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)

For some JDBC drivers (for example, Oracle) you have to explicitly list the column names or indices of the generated keys:

PreparedStatement ps = con.prepareStatement(sql, new String[]{"USER_ID"})

How to convert a string to character array in c (or) how to extract a single char form string?

In C, there's no (real, distinct type of) strings. Every C "string" is an array of chars, zero terminated.

Therefore, to extract a character c at index i from string your_string, just use

char c = your_string[i];

Index is base 0 (first character is your_string[0], second is your_string[1]...).

What does "make oldconfig" do exactly in the Linux kernel makefile?

Updates an old config with new/changed/removed options.

Perform commands over ssh with Python

Asking User to enter the command as per the device they are logging in.
The below code is validated by

import paramiko
import xlrd
import time

ssh = paramiko.SSHClient()
loc = ('/Users/harshgow/Documents/PYTHON_WORK/labcred.xlsx')
wo = xlrd.open_workbook(loc)
sheet = wo.sheet_by_index(0)
Host = sheet.cell_value(0, 1)
Port = int(sheet.cell_value(3, 1))
User = sheet.cell_value(1, 1)
Pass = sheet.cell_value(2, 1)

def details(Host, Port, User, Pass):
    ssh.connect(Host, Port, User, Pass)
    print('connected to ip ', Host)
    stdin, stdout, stderr = ssh.exec_command("")
    x = input('Enter the command:')

details(Host, Port, User, Pass)

Rename a file using Java

If it's just renaming the file, you can use File.renameTo().

In the case where you want to append the contents of the second file to the first, take a look at FileOutputStream with the append constructor option or The same thing for FileWriter. You'll need to read the contents of the file to append and write them out using the output stream/writer.

Navigation Controller Push View Controller

Use this code in your button action (Swift 3.0.1):

let vc = self.storyboard?.instantiateViewController(
    withIdentifier: "YourSecondVCIdentifier") as! SecondVC

navigationController?.pushViewController(vc, animated: true)

Get distance between two points in canvas

If you have the coordinates, use the formula to calculate the distance:

var dist = Math.sqrt( Math.pow((x1-x2), 2) + Math.pow((y1-y2), 2) );

If your platform supports the ** operator, you can instead use that:

const dist = Math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2);

How can I delay a method call for 1 second?

You could also use a block

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 1 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
    [object method]; 

Most of time you will want to use dispatch_get_main_queue, although if there is no UI in the method you could use a global queue.


Swift 3 version:

DispatchQueue.main.asyncAfter(deadline: .now() + 1) {

Equally, might also be a good option.

Environment variables in Mac OS X

There are several places where you can set environment variables.

  • ~/.profile: use this for variables you want to set in all programs launched from the terminal (note that, unlike on Linux, all shells opened in are login shells).
  • ~/.bashrc: this is invoked for shells which are not login shells. Use this for aliases and other things which need to be redefined in subshells, not for environment variables that are inherited.
  • /etc/profile: this is loaded before ~/.profile, but is otherwise equivalent. Use it when you want the variable to apply to terminal programs launched by all users on the machine (assuming they use bash).
  • ~/.MacOSX/environment.plist: this is read by loginwindow on login. It applies to all applications, including GUI ones, except those launched by Spotlight in 10.5 (not 10.6). It requires you to logout and login again for changes to take effect. This file is no longer supported as of OS X 10.8.
  • your user's launchd instance: this applies to all programs launched by the user, GUI and CLI. You can apply changes at any time by using the setenv command in launchctl. In theory, you should be able to put setenv commands in ~/.launchd.conf, and launchd would read them automatically when the user logs in, but in practice support for this file was never implemented. Instead, you can use another mechanism to execute a script at login, and have that script call launchctl to set up the launchd environment.
  • /etc/launchd.conf: this is read by launchd when the system starts up and when a user logs in. They affect every single process on the system, because launchd is the root process. To apply changes to the running root launchd you can pipe the commands into sudo launchctl.

The fundamental things to understand are:

  • environment variables are inherited by a process's children at the time they are forked.
  • the root process is a launchd instance, and there is also a separate launchd instance per user session.
  • launchd allows you to change its current environment variables using launchctl; the updated variables are then inherited by all new processes it forks from then on.

Example of setting an environment variable with launchd:


Now, launch your GUI app that uses the variable, and voila!

To work around the fact that ~/.launchd.conf does not work, you can put the following script in ~/Library/LaunchAgents/local.launchd.conf.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "">
<plist version="1.0">
    <string>launchctl &lt; ~/.launchd.conf</string>    

Then you can put setenv REPLACE_WITH_VAR REPLACE_WITH_VALUE inside ~/.launchd.conf, and it will be executed at each login.

Note that, when piping a command list into launchctl in this fashion, you will not be able to set environment variables with values containing spaces. If you need to do so, you can call launchctl as follows: launchctl setenv MYVARIABLE "QUOTE THE STRING".

Also, note that other programs that run at login may execute before the launchagent, and thus may not see the environment variables it sets.

Trying to include a library, but keep getting 'undefined reference to' messages

Yes, It is required to add libraries after the source files/objects files. This command will solve the problem:

gcc -static -L/usr/lib -I/usr/lib main.c -ltommath

IN vs ANY operator in PostgreSQL

There are two obvious points, as well as the points in the other answer:

  • They are exactly equivalent when using sub queries:

    SELECT * FROM table
    WHERE column IN(subquery);
    SELECT * FROM table
    WHERE column = ANY(subquery);

On the other hand:

  • Only the IN operator allows a simple list:

    SELECT * FROM table
    WHERE column IN(… , … , …);

Presuming they are exactly the same has caught me out several times when forgetting that ANY doesn’t work with lists.

c - warning: implicit declaration of function ‘printf’

You need to include a declaration of the printf() function.

#include <stdio.h>


Actually they are the same. LEFT OUTER JOIN is same as LEFT JOIN and RIGHT OUTER JOIN is same as RIGHT JOIN. It is more informative way to compare from INNER Join.

See this Wikipedia article for details.

Can't update data-attribute value

If we wanted to retrieve or update these attributes using existing, native JavaScript, then we can do so using the getAttribute and setAttribute methods as shown below:


// 'Getting' data-attributes using getAttribute
var plant = document.getElementById('strawberry-plant');
var fruitCount = plant.getAttribute('data-fruit'); // fruitCount = '12'

// 'Setting' data-attributes using setAttribute
plant.setAttribute('data-fruit','7'); // Pesky birds

Through jQuery

// Fetching data
var fruitCount = $(this).data('fruit');

// Above does not work in firefox. So use below to get attribute value.
var fruitCount = $(this).attr('data-fruit');

// Assigning data

// But when you get the value again, it will return old value. 
// You have to set it as below to update value. Then you will get updated value.

Read this documentation for vanilla js or this documentation for jquery

use Lodash to sort array of object by value

This method orderBy does not change the input array, you have to assign the result to your array :

var chars = this.state.characters;

chars = _.orderBy(chars, ['name'],['asc']); // Use Lodash to sort array by 'name'

 this.setState({characters: chars})

What should main() return in C and C++?

Returning 0 should tell the programmer that the program has successfully finished the job.

Why doesn't height: 100% work to expand divs to the screen height?

This may not be ideal but you can allways do it with javascript. Or in my case jQuery

var newheight = $('.innerdiv').css('height');
$('.mainwrapper').css('height', newheight);

Difference between a virtual function and a pure virtual function

You can actually provide implementations of pure virtual functions in C++. The only difference is all pure virtual functions must be implemented by derived classes before the class can be instantiated.

How do I pass the this context to a function?


var f = function () { console.log(this); }, arg1, arg2, etc);

Where that is the object which you want this in the function to be.

python 2 instead of python 3 as the (temporary) default python?

mkdir ~/bin
ln -s /usr/bin/python2 ~/bin/python

To stop using python2, exit or rm ~/bin/python.

Uses of content-disposition in an HTTP response header

Refer to RFC 6266 (Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP))

How to split a line into words separated by one or more spaces in bash?

$ line="these are words"
$ ll=($line)
$ declare -p ll  # dump the array
declare -a ll='([0]="these" [1]="are" [2]="words")'
$ for w in ${ll[@]}; do echo $w; done

jquery: animate scrollLeft

First off I should point out that css animations would probably work best if you are doing this a lot but I ended getting the desired effect by wrapping .scrollLeft inside .animate


    $('.swipeBox').animate( { scrollLeft: '+=460' }, 1000);

    $('.swipeBox').animate( { scrollLeft: '-=460' }, 1000);

The second parameter is speed, and you can also add a third parameter if you are using smooth scrolling of some sort.

Shell script not running, command not found

Add below lines in your .profile path


export PATH

Now your script should work without ./

Raj Dagla

Remove carriage return from string

If you want to remove spaces at the beginning/end of a line too(common when shortening html) you can try:


Else use the simple Replace Marc suggested.

Allowed memory size of 262144 bytes exhausted (tried to allocate 24576 bytes)

I got the same issue. To solve the issue you need to update your PHP version.

No connection could be made because the target machine actively refused it (PHP / WAMP)

Till yesterday I was able to connect to phpMyAdmin, but today I started getting this error:


None of the answers here really helped me fix the problem, what helped me is shared below:

I looked at the mysql logs.[C:\wamp\logs\mysql.log]

It said

2015-09-18 01:16:30 5920 [Note] Plugin 'FEDERATED' is disabled.
2015-09-18 01:16:30 5920 [Note] InnoDB: Using atomics to ref count buffer pool pages
2015-09-18 01:16:30 5920 [Note] InnoDB: The InnoDB memory heap is disabled
2015-09-18 01:16:30 5920 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions
2015-09-18 01:16:30 5920 [Note] InnoDB: Compressed tables use zlib 1.2.3
2015-09-18 01:16:30 5920 [Note] InnoDB: Not using CPU crc32 instructions
2015-09-18 01:16:30 5920 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2015-09-18 01:16:30 5920 [Note] InnoDB: Completed initialization of buffer pool
2015-09-18 01:16:30 5920 [Note] InnoDB: Highest supported file format is Barracuda.
2015-09-18 01:16:30 5920 [Note] InnoDB: The log sequence numbers 1765410 and 1765410 in ibdata files do not match the log sequence number 2058233 in the ib_logfiles!
2015-09-18 01:16:30 5920 [Note] InnoDB: Database was not shutdown normally!
2015-09-18 01:16:30 5920 [Note] InnoDB: Starting crash recovery.
2015-09-18 01:16:30 5920 [Note] InnoDB: Reading tablespace information from the .ibd files...
2015-09-18 01:16:30 5920 [ERROR] InnoDB: Attempted to open a previously opened tablespace. Previous tablespace harley/login_confirm uses space ID: 6 at filepath: .\harley\login_confirm.ibd. Cannot open tablespace testdb/testtable which uses space ID: 6 at filepath: .\testdb\testtable.ibd
InnoDB: Error: could not open single-table tablespace file .\testdb\testtable.ibd
InnoDB: We do not continue the crash recovery, because the table may become
InnoDB: corrupt if we cannot apply the log records in the InnoDB log to it.
InnoDB: To fix the problem and start mysqld:
InnoDB: 1) If there is a permission problem in the file and mysqld cannot
InnoDB: open the file, you should modify the permissions.
InnoDB: 2) If the table is not needed, or you can restore it from a backup,
InnoDB: then you can remove the .ibd file, and InnoDB will do a normal
InnoDB: crash recovery and ignore that table.
InnoDB: 3) If the file system or the disk is broken, and you cannot remove
InnoDB: the .ibd file, you can set innodb_force_recovery > 0 in my.cnf
InnoDB: and force InnoDB to continue crash recovery here.

I got the clue that this guy is creating a problem - InnoDB: Error: could not open single-table tablespace file .\testdb\testtable.ibd

and this line 2015-09-18 01:16:30 5920 [Note] InnoDB: Database was not shutdown normally!

hmmm, For me the testdb was just a test-db! hence I decided to delete this file inside C:\wamp\bin\mysql\mysql5.6.17\data\testdb

and restarted all services, and went to phpMyAdmin, and this time no issues, phpMyAdmin opened :)

HTML input field hint

If you mean like a text in the background, I'd say you use a label with the input field and position it on the input using CSS, of course. With JS, you fade out the label when the input receives values and fade it in when the input is empty. In this way, it is not possible for the user to submit the description, whether by accident or intent.

How can I add a table of contents to a Jupyter / JupyterLab notebook?

There is an ipython nbextension that constructs a table of contents for a notebook. It seems to only provide navigation, not section folding.

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

You can both highlight and select the item with the following 1-liner:

navigationView.getMenu().performIdentifierAction(, 0);


What is the difference between React Native and React?

Some differences are as follows:
1- React-Native is a framework which used to create Mobile Apps, where ReactJS is a javascript library you can use for your website.
2- React-Native doesn’t use HTML to render the app while React uses.
3- React-Native used for developing only Mobile App while React use for website and Mobile.

Sorting a Data Table

This worked for me:

dt.DefaultView.Sort = "Town ASC, Cutomer ASC";
dt = dt.DefaultView.ToTable();

open read and close a file in 1 line of code

use ilio: (inline io):

just one function call instead of file open(), read(), close().

from ilio import read

content = read('filename')

MySQL - How to increase varchar size of an existing column in a database without breaking existing data?

For me this has worked-

ALTER TABLE table_name ALTER COLUMN column_name VARCHAR(50)

How to delete parent element using jQuery

Use parents() instead of parent():

$("a").click(function(event) {

Set the default value in dropdownlist using jQuery

You can just do this:


video as site background? HTML 5

I might have a solution for the video as background, stretched to the browser-width or height, (but the video will still preserve the aspect ratio, couldnt find a solution for that yet.):

Put the video right after the body-tag with style="width:100%;". Right afterwords, put a "bodydummy"-tag:

<video id="bgVideo" autoplay poster="videos/poster.png">
    <source src="videos/test-h264-640x368-highqual-winff.mp4" type="video/mp4"/>
    <source src="videos/test-640x368-webmvp8-miro.webm" type="video/webm"/>
    <source src="videos/test-640x368-theora-miro.ogv" type="video/ogg"/>    

<img id="bgImg" src="videos/poster.png" />

<!-- This image stretches exactly to the browser width/height and lies behind the video-->

<div id="bodyDummy">

Put all your content inside the bodydummy-div and put the z-indexes correctly in CSS like this:

    position: absolute;
    top: 0;
    left: 0;
    border: 0;
    z-index: 1;
    width: 100%;
    height: 100%;

    position: absolute;
    top: 0;
    left: 0;
    border: 0;
    z-index: 2;
    width: 100%;
    height: 100%;

    position: absolute;
    top: 0;
    left: 0;
    z-index: 3;
    overflow: auto;
    width: 100%;
    height: 100%;

Hope I could help. Let me know when you could find a solution that the video does not maintain the aspect ratio, so it could fill the whole browser window so we do not have to put a bgimage.

jQuery Validation plugin: disable validation for specified submit buttons

You can add a CSS class of cancel to a submit button to suppress the validation


<input class="cancel" type="submit" value="Save" />

See the jQuery Validator documentation of this feature here: Skipping validation on submit


The above technique has been deprecated and replaced with the formnovalidate attribute.

<input formnovalidate="formnovalidate" type="submit" value="Save" />

Loading a .json file into c# program

I have done it like:

            using (StreamReader sr = File.OpenText(jsonFilePath))
                var myObject = JsonConvert.DeserializeObject<List<YourObject>>(sr.ReadToEnd());

also, you can do this with async call like: sr.ReadToEndAsync(). using Newtonsoft.Json as reference.

Hope, this helps.

HTTP Status 504

If your using ASP.Net 5 (now known as ASP.Net Core v1) ensure in your project.json "commands" section for each site you are hosting that the Kestrel proxy listening port differs between sites, otherwise one site will work but the other will return a 504 gateway timeout.

 "commands": {
    "web": "Microsoft.AspNet.Server.Kestrel --server.urls http://localhost:5090"

How to restart Jenkins manually?

If it is in a Docker container, you can just restart your container. Let's assume the container name is jenkins, so you can do:

docker restart jenkins


docker stop jenkins
docker start jenkins

How to split a string with angularJS

You could try this:

$scope.testdata = [{ 'name': 'name,id' }, {'name':'someName,someId'}]
$scope.array= [];
angular.forEach($scope.testdata, function (value, key) {
    $scope.array.push({ 'name':',')[0], 'id':',')[1] });

This way you can save the data for later use and acces it by using an ng-repeat like this:

<div ng-repeat="item in array">{{}}{{}}</div>

I hope this helped someone,
Plunker link: here
All credits go to @jwpfox and @Mohideen ibn Mohammed from the answer above.

./configure : /bin/sh^M : bad interpreter

If you could not found run the command,


# yum install dos2unix*

# dos2unix
dos2unix: converting file to Unix format ...

Ubuntu / Debian:

# apt-get install dos2unix

Cannot implicitly convert type 'System.DateTime?' to 'System.DateTime'. An explicit conversion exists

The problem is that you are passing a nullable type to a non-nullable type.

You can do any of the following solution:

A. Declare your dt as nullable

DateTime? dt = dateTime;

B. Use Value property of the the DateTime? datetime

DateTime dt = datetime.Value;

C. Cast it

DateTime dt = (DateTime) datetime;

How do I limit the number of results returned from grep?

Awk approach:

awk '/pattern/{print; count++; if (count==10) exit}' file

Getting coordinates of marker in Google Maps API

One more alternative options

var map = new google.maps.Map(document.getElementById('map_canvas'), {
    zoom: 1,
    center: new google.maps.LatLng(35.137879, -82.836914),
    mapTypeId: google.maps.MapTypeId.ROADMAP

var myMarker = new google.maps.Marker({
    position: new google.maps.LatLng(47.651968, 9.478485),
    draggable: true

google.maps.event.addListener(myMarker, 'dragend', function (evt) {
    document.getElementById('current').innerHTML = '<p>Marker dropped: Current Lat: ' + + ' Current Lng: ' + evt.latLng.lng().toFixed(3) + '</p>';

google.maps.event.addListener(myMarker, 'dragstart', function (evt) {
    document.getElementById('current').innerHTML = '<p>Currently dragging marker...</p>';


and html file

        <div id='map_canvas'></div>
        <div id="current">Nothing yet...</div>


In Eclipse,

Run -- > Debug Configurations --> Select "target", and select a preferred emulator target to launch.

Then Below that "additional emulator command line options," add this:

-partition-size 1024

Then CLOSE the emulator and click the debug icon, which will launch the preferred emulator you selected.

enter image description here

Hope it Helps...!

How can I delete derived data in Xcode 8?

Select Xcode and Follow 4 steps that highlighted in photo and remove derived data then restart your project.enter image description here

Specifying Font and Size in HTML table

The font tag has been deprecated for some time now.

That being said, the reason why both of your tables display with the same font size is that the 'size' attribute only accepts values ranging from 1 - 7. The smallest size is 1. The largest size is 7. The default size is 3. Any values larger than 7 will just display the same as if you had used 7, because 7 is the maximum value allowed.

And as @Alex H said, you should be using CSS for this.

What is "stdafx.h" used for in Visual Studio?

"Stdafx.h" is a precompiled header.It include file for standard system include files and for project-specific include files that are used frequently but are changed infrequently.which reduces compile time and Unnecessary Processing.

Precompiled Header stdafx.h is basically used in Microsoft Visual Studio to let the compiler know the files that are once compiled and no need to compile it from scratch. You can read more about it

Is there a "not equal" operator in Python?

Use != or <>. Both stands for not equal.

The comparison operators <> and != are alternate spellings of the same operator. != is the preferred spelling; <> is obsolescent. [Reference: Python language reference]

How do you change video src using jQuery?

The easiest way is using autoplay.

<video autoplay></video>

When you change src through javascript you don't need to mention load().

Adding blur effect to background in swift

I have tested this code and it's working fine:

let blurEffect = UIBlurEffect(style: UIBlurEffect.Style.dark)
let blurEffectView = UIVisualEffectView(effect: blurEffect)
blurEffectView.frame = view.bounds
blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

For Swift 3.0:

let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.dark)
let blurEffectView = UIVisualEffectView(effect: blurEffect)
blurEffectView.frame = view.bounds
blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

For Swift 4.0:

let blurEffect = UIBlurEffect(style: UIBlurEffect.Style.dark)
let blurEffectView = UIVisualEffectView(effect: blurEffect)
blurEffectView.frame = view.bounds
blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

Here you can see result:

blurred view

Or you can use this lib for that:

How to rotate portrait/landscape Android emulator?

Yes. Thanks

Ctrl + F11 for Portrait


Ctrl + F12 for Landscape

Get a list of URLs from a site

Write a spider which reads in every html from disk and outputs every "href" attribute of an "a" element (can be done with a parser). Keep in mind which links belong to a certain page (this is common task for a MultiMap datastructre). After this you can produce a mapping file which acts as the input for the 404 handler.

Merge up to a specific commit

Run below command into the current branch folder to merge from this <commit-id> to current branch, --no-commit do not make a new commit automatically

git merge --no-commit <commit-id>

git merge --continue can only be run after the merge has resulted in conflicts.

git merge --abort Abort the current conflict resolution process, and try to reconstruct the pre-merge state.

How to draw a rectangle around a region of interest in python

As the other answers said, the function you need is cv2.rectangle(), but keep in mind that the coordinates for the bounding box vertices need to be integers if they are in a tuple, and they need to be in the order of (left, top) and (right, bottom). Or, equivalently, (xmin, ymin) and (xmax, ymax).

SimpleDateFormat parse loses timezone


what is the way to retrieve a Date object so that its always in GMT? 


You are using troublesome confusing old date-time classes that are now supplanted by the java.time classes.

Instant = UTC

The Instant class represents a moment on the timeline in UTC with a resolution of nanoseconds (up to nine (9) digits of a decimal fraction).

Instant instant = ; // Current moment in UTC.

ISO 8601

To exchange this data as text, use the standard ISO 8601 formats exclusively. These formats are sensibly designed to be unambiguous, easy to process by machine, and easy to read across many cultures by people.

The java.time classes use the standard formats by default when parsing and generating strings.

String output = instant.toString() ;  


Time zone

If you want to see that same moment as presented in the wall-clock time of a particular region, apply a ZoneId to get a ZonedDateTime.

Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).

ZoneId z = ZoneId.of( "Asia/Singapore" ) ;
ZonedDateTime zdt = instant.atZone( z ) ;  // Same simultaneous moment, same point on the timeline.

See this code live at

Notice the eight hour difference, as the time zone of Asia/Singapore currently has an offset-from-UTC of +08:00. Same moment, different wall-clock time.

instant.toString(): 2017-01-23T12:34:56.123456789Z

zdt.toString(): 2017-01-23T20:34:56.123456789+08:00[Asia/Singapore]


Avoid the legacy java.util.Date class. But if you must, you can convert. Look to new methods added to the old classes.

java.util.Date date = Date.from( instant ) ;

…going the other way…

Instant instant = myJavaUtilDate.toInstant() ;


For date-only, use LocalDate.

LocalDate ld = zdt.toLocalDate() ;

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

C++ for each, pulling from vector elements

C++ does not have the for_each loop feature in its syntax. You have to use c++11 or use the template function std::for_each.

struct Function {
    int input;
    Function(int input): input(input) {}
    void operator()(Attack& attack) {
        if(attack->m_num == input) attack->makeDamage();
Function f(input);
std::for_each(m_attack.begin(), m_attack.end(), f);

Responsive css background images

Adaptive for square ratio with jQuery

var Height = $(window).height();
var Width = $(window).width();
var HW = Width/Height;

      $(".background").css("background-size","auto 100%");
    else if(HW>1){
      $(".background").css("background-size","100% auto");

Android Button Onclick

You need to make the same method name both in layout XML and java code.

If you use android:onClick="setLogin" then you need to make a method with the same name, setLogin:

// Please be noted that you need to add the "View v" parameter
public void setLogin(View v) {


Do not mix layout with code by using android:onClick tag in your XML. Instead, move the click method to your class with OnClickListener method like:

Button button = (Button) findViewById(;
button.setOnClickListener(new OnClickListener() {
  public void onClick(View v) {
    // TODO Auto-generated method stub

Make a layout just for layout and no more. It will save your precious time when you need to refactoring for Supporting Multiple Screens.

Ruby Array find_first object?

Do you need the object itself or do you just need to know if there is an object that satisfies. If the former then yes: use find:

found_object = my_array.find { |e| e.satisfies_condition? }

otherwise you can use any?

found_it = my_array.any?  { |e| e.satisfies_condition? }

The latter will bail with "true" when it finds one that satisfies the condition. The former will do the same, but return the object.

Nested objects in javascript, best practices

If you know the settings in advance you can define it in a single statement:

var defaultsettings = {
                        ajaxsettings : { "ak1" : "v1", "ak2" : "v2", etc. },
                        uisettings : { "ui1" : "v1", "ui22" : "v2", etc }

If you don't know the values in advance you can just define the top level object and then add properties:

var defaultsettings = { };
defaultsettings["ajaxsettings"] = {};
defaultsettings["ajaxsettings"]["somekey"] = "some value";

Or half-way between the two, define the top level with nested empty objects as properties and then add properties to those nested objects:

var defaultsettings = {
                        ajaxsettings : {  },
                        uisettings : {  }

defaultsettings["ajaxsettings"]["somekey"] = "some value";
defaultsettings["uisettings"]["somekey"] = "some value";

You can nest as deep as you like using the above techniques, and anywhere that you have a string literal in the square brackets you can use a variable:

var keyname = "ajaxsettings";
var defaultsettings = {};
defaultsettings[keyname] = {};
defaultsettings[keyname]["some key"] = "some value";

Note that you can not use variables for key names in the { } literal syntax.

How to output to the console in C++/Windows

Since you mentioned stdout.txt I google'd it to see what exactly would create a stdout.txt; normally, even with a Windows app, console output goes to the allocated console, or nowhere if one is not allocated.

So, assuming you are using SDL (which is the only thing that brought up stdout.txt), you should follow the advice here. Either freopen stdout and stderr with "CON", or do the other linker/compile workarounds there.

In case the link gets broken again, here is exactly what was referenced from libSDL:

How do I avoid creating stdout.txt and stderr.txt?

"I believe inside the Visual C++ project that comes with SDL there is a SDL_nostdio target > you can build which does what you want(TM)."

"If you define "NO_STDIO_REDIRECT" and recompile SDL, I think it will fix the problem." > > (Answer courtesy of Bill Kendrick)

AngularJS - Binding radio buttons to models with boolean values

You might take a look at this:

This guy wrote a custom directive to get around the issue that "true" and "false" are strings, not booleans.

How to suspend/resume a process in Windows?

You can't do it from the command line, you have to write some code (I assume you're not just looking for an utility otherwise Super User may be a better place to ask). I also assume your application has all the required permissions to do it (examples are without any error checking).

Hard Way

First get all the threads of a given process then call the SuspendThread function to stop each one (and ResumeThread to resume). It works but some applications may crash or hung because a thread may be stopped in any point and the order of suspend/resume is unpredictable (for example this may cause a dead lock). For a single threaded application this may not be an issue.

void suspend(DWORD processId)
    HANDLE hThreadSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0);

    THREADENTRY32 threadEntry; 
    threadEntry.dwSize = sizeof(THREADENTRY32);

    Thread32First(hThreadSnapshot, &threadEntry);

        if (threadEntry.th32OwnerProcessID == processId)
            HANDLE hThread = OpenThread(THREAD_ALL_ACCESS, FALSE,

    } while (Thread32Next(hThreadSnapshot, &threadEntry));


Please note that this function is even too much naive, to resume threads you should skip threads that was suspended and it's easy to cause a dead-lock because of suspend/resume order. For single threaded applications it's prolix but it works.

Undocumented way

Starting from Windows XP there is the NtSuspendProcess but it's undocumented. Read this post for a code example (reference for undocumented functions: news://

typedef LONG (NTAPI *NtSuspendProcess)(IN HANDLE ProcessHandle);

void suspend(DWORD processId)
    HANDLE processHandle = OpenProcess(PROCESS_ALL_ACCESS, FALSE, processId));

    NtSuspendProcess pfnNtSuspendProcess = (NtSuspendProcess)GetProcAddress(
        GetModuleHandle("ntdll"), "NtSuspendProcess");


"Debugger" Way

To suspend a program is what usually a debugger does, to do it you can use the DebugActiveProcess function. It'll suspend the process execution (with all threads all together). To resume you may use DebugActiveProcessStop.

This function lets you stop a process (given its Process ID), syntax is very simple: just pass the ID of the process you want to stop et-voila. If you'll make a command line application you'll need to keep its instance running to keep the process suspended (or it'll be terminated). See the Remarks section on MSDN for details.

void suspend(DWORD processId)

From Command Line

As I said Windows command line has not any utility to do that but you can invoke a Windows API function from PowerShell. First install Invoke-WindowsApi script then you can write this:

Invoke-WindowsApi "kernel32" ([bool]) "DebugActiveProcess" @([int]) @(process_id_here)

Of course if you need it often you can make an alias for that.

Platform.runLater and Task in JavaFX

  • Platform.runLater: If you need to update a GUI component from a non-GUI thread, you can use that to put your update in a queue and it will be handled by the GUI thread as soon as possible.
  • Task implements the Worker interface which is used when you need to run a long task outside the GUI thread (to avoid freezing your application) but still need to interact with the GUI at some stage.

If you are familiar with Swing, the former is equivalent to SwingUtilities.invokeLater and the latter to the concept of SwingWorker.

The javadoc of Task gives many examples which should clarify how they can be used. You can also refer to the tutorial on concurrency.

UML diagram shapes missing on Visio 2013

Please check this KB article : This issue occurs because Visio 2013 uses new UML and database modeling templates that are not used by Visio 2010 or by earlier versions of Visio. And it applies to both :

"Microsoft Visio Professional 2013" and "Microsoft Visio Standard 2013"

So upgrading to Pro might not help as well.

format statement in a string resource file

Quote from Android Docs:

If you need to format your strings using String.format(String, Object...), then you can do so by putting your format arguments in the string resource. For example, with the following resource:

<string name="welcome_messages">Hello, %1$s! You have %2$d new messages.</string>

In this example, the format string has two arguments: %1$s is a string and %2$d is a decimal number. You can format the string with arguments from your application like this:

Resources res = getResources();
String text = String.format(res.getString(R.string.welcome_messages), username, mailCount);

Why can't I change my input value in React even with the onChange listener

Unlike in the case of Angular, in React.js you need to update the state manually. You can do something like this:

    type="text" value={}
    id={'todoName' +}
    onChange={e => this.onTodoChange(}

And then in the function:

             name: value

Also, you can set the initial state in the constructor of the component:

  constructor (props) {
    this.state = {
        updatable: false,
        status: props.status

How to count the number of words in a sentence, ignoring numbers, punctuation and whitespace?

How about using a simple loop to count the occurrences of number of spaces!?

txt = "Just an example here move along" _x000D_
count = 1_x000D_
for i in txt:_x000D_
if i == " ":_x000D_
   count += 1_x000D_

What is float in Java?

In JAVA, values like:

  1. 8.5
  2. 3.9
  3. (and so on..)

Is assumed as double and not float.

You can also perform a cast in order to solve the problem:

float b = (float) 3.5;

Another solution:

float b = 3.5f;

Convert default format to Timestamp in Java


I am providing the modern answer. The Timestamp class was always poorly designed, a real hack on top of the already poorly designed Date class. Both those classes are now long outdated. Don’t use them.

When the question was asked, you would need a Timestamp for sending a point in time to the SQL database. Since JDBC 4.2 that is no longer the case. Assuming your database needs a timestamp with time zone (recommended for true timestamps), pass it an OffsetDateTime.

Before we can do that we need to overcome a real trouble with your sample string, Mon May 27 11:46:15 IST 2013: the time zone abbreviation. IST may mean Irish Summer Time, Israel Standard Time or India Standard Time (I have even read that Java may parse it into Atlantic/Reykjavik time zone — Icelandic Standard Time?) To control the interpretation we pass our preferred time zone to the formatter that we are using for parsing.

    DateTimeFormatter formatter = new DateTimeFormatterBuilder()
            .appendPattern("EEE MMM dd HH:mm:ss ")
            .appendZoneText(TextStyle.SHORT, Set.of(ZoneId.of("Asia/Kolkata")))
            .appendPattern(" yyyy")
    String dateString = "Mon May 27 11:46:15 IST 2013";
    OffsetDateTime dateTime = formatter.parse(dateString, Instant::from)

This snippet prints:


This is the UTC equivalent of your string (assuming IST was for India Standard Time). Pass the OffsetDateTime to your database using one of the PreparedStatement.setObject methods (not setTimestamp).

How can I convert this into timestamp and calculate in seconds the difference between the same and current time?

Calculating the difference in seconds goes very naturally with java.time:

    long differenceInSeconds = ChronoUnit.SECONDS

When running just now I got:


Link: Oracle tutorial: Date Time explaining how to use java.time.

When should you use 'friend' in C++?

The friend keyword has a number of good uses. Here are the two uses immediately visible to me:

Friend Definition

Friend definition allows to define a function in class-scope, but the function will not be defined as a member function, but as a free function of the enclosing namespace, and won't be visible normally except for argument dependent lookup. That makes it especially useful for operator overloading:

namespace utils {
    class f {
        typedef int int_type;
        int_type value;

        // let's assume it doesn't only need .value, but some
        // internal stuff.
        friend f operator+(f const& a, f const& b) {
            // name resolution finds names in class-scope. 
            // int_type is visible here.
            return f(a.value + b.value);

        int getValue() const { return value; }

int main() {
    utils::f a, b;
    std::cout << (a + b).getValue(); // valid

Private CRTP Base Class

Sometimes, you find the need that a policy needs access to the derived class:

// possible policy used for flexible-class.
template<typename Derived>
struct Policy {
    void doSomething() {
        // casting this to Derived* requires us to see that we are a 
        // base-class of Derived.
        some_type const& t = static_cast<Derived*>(this)->getSomething();

// note, derived privately
template<template<typename> class SomePolicy>
struct FlexibleClass : private SomePolicy<FlexibleClass> {
    // we derive privately, so the base-class wouldn't notice that, 
    // (even though it's the base itself!), so we need a friend declaration
    // to make the base a friend of us.
    friend class SomePolicy<FlexibleClass>;

    void doStuff() {
         // calls doSomething of the policy

    // will return useful information
    some_type getSomething();

You will find a non-contrived example for that in this answer. Another code using that is in this answer. The CRTP base casts its this pointer, to be able to access data-fields of the derived class using data-member-pointers.

SQL Query To Obtain Value that Occurs more than once

From Oracle (but works in most SQL DBs):


P.S. it's faster one, because you have no Select withing Select methods here

How can I fix the Microsoft Visual Studio error: "package did not load correctly"?

  • Close Visual Studio.

  • Backup and delete the following path:


  • Restart Visual Studio as Admin. Otherwise, the Roaming folder can't be repaired by Visual Studio.

Jquery to change form action

Please, see this answer:

Quoting Tamlyn:

jQuery (1.4.2) gets confused if you have any form elements named "action". You can get around this by using the DOM attribute methods or simply avoid having form elements named "action".

<form action="foo">
  <button name="action" value="bar">Go</button>

<script type="text/javascript">
  $('form').attr('action', 'baz'); //this fails silently
  $('form').get(0).setAttribute('action', 'baz'); //this works

Use curly braces to initialize a Set in Python

You need to do empty_set = set() to initialize an empty set. {} is an empty dict.

CSS: 100% width or height while keeping aspect ratio?

Had the same issue. The problem for me was that the height property was also already defined elsewhere, fixed it like this:

    max-width: 100%;
    max-height: 100%;
    height: inherit !important;

Regex doesn't work in String.matches()

String.matches returns whether the whole string matches the regex, not just any substring.

JDK on OSX 10.7 Lion

I have just ran into the same problem after updating. The JRE that is downloaded by OSX Lion is missing JavaRuntimeSupport.jar which will work but can wreck havoc on a lot of things. If you've updated, and you had a working JDK/JRE installed prior to that, do the following in Eclipse:

1) Project > Properties > Java Build Path > Select broken JRE/JDK > Edit

2) Select "Alternate JRE"

3) Click "Installed JREs..."

4) In the window that opens, click "Search..."

If all goes well, it will find your older JRE/JDK. Mine was in this location:


How to create empty data frame with column names specified in R?

Just create a data.frame with 0 length variables


nodata <- data.frame(x= numeric(0), y= integer(0), z = character(0))

## 'data.frame':    0 obs. of  3 variables:
##  $ x: num 
##  $ y: int 
##  $ z: Factor w/ 0 levels: 

or to create a data.frame with 5 columns named a,b,c,d,e

nodata <-,numeric(0), simplify = F), letters[1:5]))

SQL WHERE.. IN clause multiple columns

If you want for one table then use following query

FROM Student_info S
  INNER JOIN Student_info UT
    ON =
    AND S.studentName = UT.studentName
where in (1,2) and S.studentName in ('a','b')

and table data as follow

1   a   ad  ca
2   b   bd  bd
3   a   ad  ad
4   b   bd  bd
5   c   cd  cd

Then output as follow

1   a   ad  ca
2   b   bd  bd

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


if __name__ == "__main__":

It checks if the __name__ attribute of the Python script is "__main__". In other words, if the program itself is executed, the attribute will be __main__, so the program will be executed (in this case the main() function).

However, if your Python script is used by a module, any code outside of the if statement will be executed, so if \__name__ == "\__main__" is used just to check if the program is used as a module or not, and therefore decides whether to run the code.

Is it possible to specify condition in Count()?

SELECT COUNT(*) FROM bla WHERE Position = 'Manager'

Is there a reason for C#'s reuse of the variable in a foreach?

Having been bitten by this, I have a habit of including locally defined variables in the innermost scope which I use to transfer to any closure. In your example:

foreach (var s in strings)
    query = query.Where(i => i.Prop == s); // access to modified closure

I do:

foreach (var s in strings)
    string search = s;
    query = query.Where(i => i.Prop == search); // New definition ensures unique per iteration.

Once you have that habit, you can avoid it in the very rare case you actually intended to bind to the outer scopes. To be honest, I don't think I have ever done so.

How to declare or mark a Java method as deprecated?

Use both @Deprecated annotation and the @deprecated JavaDoc tag.

The @deprecated JavaDoc tag is used for documentation purposes.

The @Deprecated annotation instructs the compiler that the method is deprecated. Here is what it says in Sun/Oracles document on the subject:

Using the @Deprecated annotation to deprecate a class, method, or field ensures that all compilers will issue warnings when code uses that program element. In contrast, there is no guarantee that all compilers will always issue warnings based on the @deprecated Javadoc tag, though the Sun compilers currently do so. Other compilers may not issue such warnings. Thus, using the @Deprecated annotation to generate warnings is more portable that relying on the @deprecated Javadoc tag.

You can find the full document at How and When to Deprecate APIs

How to use subList()

I've implemented and tested this one; it should cover most bases:

public static <T> List<T> safeSubList(List<T> list, int fromIndex, int toIndex) {
    int size = list.size();
    if (fromIndex >= size || toIndex <= 0 || fromIndex >= toIndex) {
        return Collections.emptyList();

    fromIndex = Math.max(0, fromIndex);
    toIndex = Math.min(size, toIndex);

    return list.subList(fromIndex, toIndex);

How to check if a variable is equal to one string or another string?

This does not do what you expect:

if var is 'stringone' or 'stringtwo':

It is the same as:

if (var is 'stringone') or 'stringtwo':

Which is always true, since 'stringtwo' is considered a "true" value.

There are two alternatives:

if var in ('stringone', 'stringtwo'):

Or you can write separate equality tests,

if var == 'stringone' or var == 'stringtwo':

Don't use is, because is compares object identity. You might get away with it sometimes because Python interns a lot of strings, just like you might get away with it in Java because Java interns a lot of strings. But don't use is unless you really want object identity.

>>> 'a' + 'b' == 'ab'
>>> 'a' + 'b' is 'abc'[:2]
False # but could be True
>>> 'a' + 'b' is 'ab'
True  # but could be False

How do I set the driver's python version in spark?

If you are working on mac, use the following commands

export SPARK_HOME=`brew info apache-spark | grep /usr | tail -n 1 | cut -f 1 -d " "`/libexec

export HADOOP_HOME=`brew info hadoop | grep /usr | head -n 1 | cut -f 1 -d " "`/libexec
export PYSPARK_PYTHON=python3

If you are using another OS, check the following link:

C# Collection was modified; enumeration operation may not execute

The problem is where you are executing:

rankings[kvp.Key] = rankings[kvp.Key] + 4;

You cannot modify the collection you are iterating through in a foreach loop. A foreach loop requires the loop to be immutable during iteration.

Instead, use a standard 'for' loop or create a new loop that is a copy and iterate through that while updating your original.

Entity Framework Query for inner join

In case anyone's interested in the Method syntax, if you have a navigation property, it's way easy:

db.Services.Where(s=>s.ServiceAssignment.LocationId == 1);

If you don't, unless there's some Join() override I'm unaware of, I think it looks pretty gnarly (and I'm a Method syntax purist):

     s => s.Id,
     sa => sa.ServiceId, 
     (s, sa) => new {service = s, asgnmt = sa})
.Where(ssa => ssa.asgnmt.LocationId == 1)
.Select(ssa => ssa.service);

How do I get current URL in Selenium Webdriver 2 Python?

Another way to do it would be to inspect the url bar in chrome to find the id of the element, have your WebDriver click that element, and then send the keys you use to copy and paste using the keys common function from selenium, and then printing it out or storing it as a variable, etc.

How to parse JSON in Kotlin?

A bit late, but whatever.

If you prefer parsing JSON to JavaScript-like constructs making use of Kotlin syntax, I recommend JSONKraken, of which I am the author.

Suggestions and opinions on the matter are much apreciated!

jQuery form validation on button click

Within your click handler, the mistake is the .validate() method; it only initializes the plugin, it does not validate the form.

To eliminate the need to have a submit button within the form, use .valid() to trigger a validation check...

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

jsFiddle Demo

.validate() - to initialize the plugin (with options) once on DOM ready.

.valid() - to check validation state (boolean value) or to trigger a validation test on the form at any time.

Otherwise, if you had a type="submit" button within the form container, you would not need a special click handler and the .valid() method, as the plugin would capture that automatically.

Demo without click handler


You also have two issues within your HTML...

<input id="field1" type="text" class="required">
  • You don't need class="required" when declaring rules within .validate(). It's redundant and superfluous.

  • The name attribute is missing. Rules are declared within .validate() by their name. The plugin depends upon unique name attributes to keep track of the inputs.

Should be...

<input name="field1" id="field1" type="text" />

SQL Inner-join with 3 tables?

If you have 3 tables with the same ID to be joined, I think it would be like this:

SELECT * FROM table1 a
JOIN table2 b ON a.ID = b.ID
JOIN table3 c ON a.ID = c.ID

Just replace * with what you want to get from the tables.

docker : invalid reference format

I had a similar problem. Issue I was having was $(pwd) has a space in there which was throwing docker run off.

Change the directory name to not have spaces in there, and it should work if this is the problem

Using PHP Replace SPACES in URLS with %20

You've got several options how to do this, either:


Assuming that you want to replace "\t" and " " with "%20":

$replace_pairs = array(
  "\t" => '%20',
  " " => '%20',
return strtr( $text, $replace_pairs)


You've got few options here, either replacing just space ~ ~, again replacing space and tab ~[ \t]~ or all kinds of spaces ~\s~:

return preg_replace( '~\s~', '%20', $text);

Or when you need to replace string like this "\t \t \t \t" with just one %20:

return preg_replace( '~\s+~', '%20', $text);

I assumed that you really want to use manual string replacement and handle more types of whitespaces such as non breakable space (&nbsp;)

How to detect READ_COMMITTED_SNAPSHOT is enabled?

Neither on SQL2005 nor 2012 does DBCC USEROPTIONS show is_read_committed_snapshot_on:

Set Option  Value
textsize    2147483647
language    us_english
dateformat  mdy
datefirst   7
lock_timeout    -1
quoted_identifier   SET
arithabort  SET
ansi_null_dflt_on   SET
ansi_warnings   SET
ansi_padding    SET
ansi_nulls  SET
concat_null_yields_null SET
isolation level read committed

"The stylesheet was not loaded because its MIME type, "text/html" is not "text/css"

Actually I had wrongly put href="", and hence the html file was referencing itself as the CSS. Mozilla had the similar bug once, and I got the answer from there.

How to pass ArrayList<CustomeObject> from one activity to another?

you need implements Parcelable in your ContactBean class, I put one example for you:

public class ContactClass implements Parcelable {

private String id;
private String photo;
private String firstname;
private String lastname;

public ContactClass()


private ContactClass(Parcel in) {
    firstname = in.readString();
    lastname = in.readString();
    photo = in.readString();
    id = in.readString();


public int describeContents() {
    // TODO Auto-generated method stub
    return 0;

public void writeToParcel(Parcel dest, int flags) {



 public static final Parcelable.Creator<ContactClass> CREATOR = new Parcelable.Creator<ContactClass>() {
        public ContactClass createFromParcel(Parcel in) {
            return new ContactClass(in);

        public ContactClass[] newArray(int size) {
            return new ContactClass[size];


   // all get , set method 

and this get and set for your code:

Intent intent = new Intent(this,DisplayContact.class);
intent.putExtra("Contact_list", ContactLis);

second class:

ArrayList<ContactClass> myList = getIntent().getParcelableExtra("Contact_list");

On duplicate key ignore?

Would suggest NOT using INSERT IGNORE as it ignores ALL errors (ie its a sloppy global ignore). Instead, since in your example tag is the unique key, use:

INSERT INTO table_tags (tag) VALUES ('tag_a'),('tab_b'),('tag_c') ON DUPLICATE KEY UPDATE tag=tag;

on duplicate key produces:

Query OK, 0 rows affected (0.07 sec)

Get PostGIS version

Other way to get the minor version is:

SELECT extversion
FROM pg_catalog.pg_extension
WHERE extname='postgis'

How to animate CSS Translate

There are jQuery-plugins that help you achieve this like:

Error 0x80005000 and DirectoryServices

This Error can occur if the physical machine has run out of memory. In my case i was hosting a site on IIS trying to access the AD, but the server had run out of memory.

CSS to hide INPUT BUTTON value text

Why are you including the value attribute at all? From memory, you don't need to specify it (although HTML standards may say you do - not sure). If you do need a value attribute, why not just state value=""?

If you do take this approach, your CSS will need additional properties for the height and width of the background image.

"FATAL: Module not found error" using modprobe

Ensure that your network is brought down before loading module:

sudo stop networking

It helped me -

AngularJS - Does $destroy remove event listeners?

Event listeners

First off it's important to understand that there are two kinds of "event listeners":

  1. Scope event listeners registered via $on:

    $scope.$on('anEvent', function (event, data) {
  2. Event handlers attached to elements via for example on or bind:

    element.on('click', function (event) {


When $scope.$destroy() is executed it will remove all listeners registered via $on on that $scope.

It will not remove DOM elements or any attached event handlers of the second kind.

This means that calling $scope.$destroy() manually from example within a directive's link function will not remove a handler attached via for example element.on, nor the DOM element itself.


Note that remove is a jqLite method (or a jQuery method if jQuery is loaded before AngularjS) and is not available on a standard DOM Element Object.

When element.remove() is executed that element and all of its children will be removed from the DOM together will all event handlers attached via for example element.on.

It will not destroy the $scope associated with the element.

To make it more confusing there is also a jQuery event called $destroy. Sometimes when working with third-party jQuery libraries that remove elements, or if you remove them manually, you might need to perform clean up when that happens:

element.on('$destroy', function () {

What to do when a directive is "destroyed"

This depends on how the directive is "destroyed".

A normal case is that a directive is destroyed because ng-view changes the current view. When this happens the ng-view directive will destroy the associated $scope, sever all the references to its parent scope and call remove() on the element.

This means that if that view contains a directive with this in its link function when it's destroyed by ng-view:

scope.$on('anEvent', function () {

element.on('click', function () {

Both event listeners will be removed automatically.

However, it's important to note that the code inside these listeners can still cause memory leaks, for example if you have achieved the common JS memory leak pattern circular references.

Even in this normal case of a directive getting destroyed due to a view changing there are things you might need to manually clean up.

For example if you have registered a listener on $rootScope:

var unregisterFn = $rootScope.$on('anEvent', function () {});

scope.$on('$destroy', unregisterFn);

This is needed since $rootScope is never destroyed during the lifetime of the application.

The same goes if you are using another pub/sub implementation that doesn't automatically perform the necessary cleanup when the $scope is destroyed, or if your directive passes callbacks to services.

Another situation would be to cancel $interval/$timeout:

var promise = $interval(function () {}, 1000);

scope.$on('$destroy', function () {

If your directive attaches event handlers to elements for example outside the current view, you need to manually clean those up as well:

var windowClick = function () {

angular.element(window).on('click', windowClick);

scope.$on('$destroy', function () {
  angular.element(window).off('click', windowClick);

These were some examples of what to do when directives are "destroyed" by Angular, for example by ng-view or ng-if.

If you have custom directives that manage the lifecycle of DOM elements etc. it will of course get more complex.

How can I copy a conditional formatting from one document to another?

To copy conditional formatting from google spreadsheet (doc1) to another (doc2) you need to do the following:

  1. Go to the bottom of doc1 and right-click on the sheet name.
  2. Select Copy to
  3. Select doc2 from the options you have (note: doc2 must be on your google drive as well)
  4. Go to doc2 and open the newly "pasted" sheet at the bottom (it should be the far-right one)
  5. Select the cell with the formatting you want to use and copy it.
  6. Go to the sheet in doc2 you would like to modify.
  7. Select the cell you want your formatting to go to.
  8. Right click and choose paste special and then paste conditional formatting only
  9. Delete the pasted sheet if you don't want it there. Done.

How to list all dates between two dates

Use this,

DECLARE @start_date DATETIME = '2015-02-12 00:00:00.000';
DECLARE @end_date DATETIME = '2015-02-13 00:00:00.000';

WITH    AllDays
          AS ( SELECT   @start_date AS [Date], 1 AS [level]
               UNION ALL
               SELECT   DATEADD(DAY, 1, [Date]), [level] + 1
               FROM     AllDays
               WHERE    [Date] < @end_date )
     SELECT [Date], [level]

pass the @start_date and @end_date as SP parameters.


Date                    level
----------------------- -----------
2015-02-12 00:00:00.000 1
2015-02-13 00:00:00.000 2

(2 row(s) affected)

Spring MVC: Error 400 The request sent by the client was syntactically incorrect

Controller trying to find the "action" value in bean but according to your example you have not set any bean name of "action". try to do name="action". @RequestParam always find in the bean class.

Convert and format a Date in JSP

In JSP, you'd normally like to use JSTL <fmt:formatDate> for this. You can of course also throw in a scriptlet with SimpleDateFormat, but scriptlets are strongly discouraged since 2003.

Assuming that ${} returns java.util.Date, here's how you can use it:

<%@ taglib prefix="fmt" uri="" %>
<fmt:formatDate value="${}" pattern="yyyy-MM-dd HH:mm:ss" />

If you're actually using a java.util.Calendar, then you can invoke its getTime() method to get a java.util.Date out of it that <fmt:formatDate> accepts:

<fmt:formatDate value="${bean.calendar.time}" pattern="yyyy-MM-dd HH:mm:ss" />

Or, if you're actually holding the date in a java.lang.String (this indicates a serious design mistake in the model; you should really fix your model to store dates as java.util.Date instead of as java.lang.String!), here's how you can convert from one date string format e.g. MM/dd/yyyy to another date string format e.g. yyyy-MM-dd with help of JSTL <fmt:parseDate>.

<fmt:parseDate pattern="MM/dd/yyyy" value="${bean.dateString}" var="parsedDate" />
<fmt:formatDate value="${parsedDate}" pattern="yyyy-MM-dd" />

Switching a DIV background image with jQuery

I did mine using regular expressions, since I wanted to preserve a relative path and not use add the addClass function. I just wanted to make it convoluted, lol.

            function() {
                $("html, body").animate({scrollTop: $(this).offset().top}, 200);
                var bgImg = $(this).css('background-image')
                var bgPath = bgImg.substr(0, bgImg.lastIndexOf('/')+1)
                if(bgImg.match(/collapse/)) {
                    $(this).stop().css('background-image', bgImg.replace(/collapse/,'expand'));
                } else {
                    $(this).stop().css('background-image', bgImg.replace(/expand/,'collapse'));

How to use regex with find command?

on Mac OS X (BSD find): Same as accepted answer, the .*/ prefix is needed to match a complete path:

$ find -E . -regex ".*/[a-f0-9\-]{36}.jpg"

man find says -E uses extended regex support

How do you trigger a block after a delay, like -performSelector:withObject:afterDelay:?

Here is how you can trigger a block after a delay in Swift:

runThisAfterDelay(seconds: 2) { () -> () in
    print("Prints this 2 seconds later in main queue")

/// EZSwiftExtensions
func runThisAfterDelay(seconds seconds: Double, after: () -> ()) {
    let time = dispatch_time(DISPATCH_TIME_NOW, Int64(seconds * Double(NSEC_PER_SEC)))
    dispatch_after(time, dispatch_get_main_queue(), after)

Its included as a standard function in my repo.

Install IPA with iTunes 11

I always use the iPhone configuration utility for this. Allows much more control and is faster - you don't have to sync the whole device.

When to use StringBuilder in Java

Some compilers may not replace any string concatenations with StringBuilder equivalents. Be sure to consider which compilers your source will use before relying on compile time optimizations.

Laravel Eloquent limit and offset

Try this sample code:

$art = Article::where('id',$article)->firstOrFail();

$products = $art->products->take($limit);

How to solve java.lang.NoClassDefFoundError?

I use the FileSync plugin for Eclipse so I can live debug on Tomcat & I received NoClassFoundError because I had added a sync entry for the bin directory in the Eclipse workspace => classes in the metadata for Tomcat but hadn't also added a folder sync for the extlib directory in Eclipse =>


Convert list to tuple in Python

l1 = []   #Empty list is given

l1 = tuple(l1)   #Through the type casting method we can convert list into tuple

print(type(l1))   #Now this show class of tuple

Checking for #N/A in Excel cell from VBA code

First check for an error (N/A value) and then try the comparisation against cvErr(). You are comparing two different things, a value and an error. This may work, but not always. Simply casting the expression to an error may result in similar problems because it is not a real error only the value of an error which depends on the expression.

If IsError(ActiveWorkbook.Sheets("Publish").Range("G4").offset(offsetCount, 0).Value) Then
  If (ActiveWorkbook.Sheets("Publish").Range("G4").offset(offsetCount, 0).Value <> CVErr(xlErrNA)) Then
    'do something
  End If
End If

Changing the interval of SetInterval while it's running

This can be initiated however you want. timeout is the method i used to keep it on the top of the hour.

I had the need for every hour to begin a code block on the hour. So this would start at server startup and run the interval hourly. Basicaly the initial run is to begin the interval within the same minute. So in a second from init, run immediately then on every 5 seconds.

var interval = 1000;
var timing =function(){
    var timer = setInterval(function(){
        if(interval == 1000){ /*interval you dont want anymore or increment/decrement */
            interval = 3600000; /* Increment you do want for timer */

Alternately if you wanted to just have something happen at start and then forever at a specific interval you could just call it at the same time as the setInterval. For example:

var this = function(){

Here we have this run the first time and then every hour.

AngularJS - Animate ng-view transitions

I'm not sure about a way to do it directly with AngularJS but you could set the display to none for both welcome and login and animate the opacity with an directive once they are loaded.

I would do it some way like so. 2 Directives for fading in the content and fading it out when a link is clicked. The directive for fadeouts could simply animate a element with an unique ID or call a service which broadcasts the fadeout


<div class="tmplWrapper" onLoadFadeIn>
    <a href="somewhere/else" fadeOut>


  .directive('onLoadFadeIn', ['Fading', function('Fading') {
    return function(scope, element, attrs) {
      scope.$on('fading', function() {
  .directive('fadeOut', function() {
    return function(scope, element, attrs) {
      element.bind('fadeOut', function(e) {


angular.factory('Fading', function() {
  var news;
  news.setActiveUnit = function() {
  return news;

I just have put together this code quickly so there may be some bugs :)

make a phone call click on a button

With permission:

Intent callIntent = new Intent(Intent.ACTION_CALL);
if (ActivityCompat.checkSelfPermission(yourActivity.this,android.Manifest.permission.CALL_PHONE) != PackageManager.PERMISSION_GRANTED) {
                if (ActivityCompat.shouldShowRequestPermissionRationale(yourActivity.this,
                        android.Manifest.permission.CALL_PHONE)) {
                } else {
                            new String[]{android.Manifest.permission.CALL_PHONE},

Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<AnonymousType#1>' to 'System.Collections.Generic.List<string>

If you have source as a string like "abcd" and want to produce a list like this:

{ "a.a" },
{ "b.b" },
{ "c.c" },
{ "d.d" }

then call:

List<string> list = source.Select(c => String.Concat(c, ".", c)).ToList();

How to convert JSON to a Ruby hash

Assuming you have a JSON hash hanging around somewhere, to automatically convert it into something like WarHog's version, wrap your JSON hash contents in %q{hsh} tags.

This seems to automatically add all the necessary escaped text like in WarHog's answer.

Angularjs: Get element in controller

I dont know what do you exactly mean but hope it help you.
by this directive you can access the DOM element inside controller
this is sample that help you to focus element inside controller

.directive('scopeElement', function () {
    return {
        restrict:"A", // E-Element A-Attribute C-Class M-Comments
        replace: false,
        link: function($scope, elem, attrs) {
            $scope[attrs.scopeElement] = elem[0];

now, inside HTML

<input scope-element="txtMessage" >

then, inside controller :

.controller('messageController', ['$scope', function ($scope) {

jQuery when element becomes visible

(function() {
    var ev = new $.Event('display'),
        orig = $.fn.css;
    $.fn.css = function() {
        orig.apply(this, arguments);

$('#element').bind('display', function(e) {
    alert("display has changed to :" + $(this).attr('style') );

$('#element').css("display", "none")// i change the style in this line !!
$('#element').css("display", "block")// i change the style in this line !!

changes will be alerted.