Programs & Examples On #Openjpa

OpenJPA is an open source implementation of the Java Persistence API specification. It is an object-relational mapping (ORM) solution for the Java language, which simplifies storing objects in databases. It is open source software distributed under the Apache 2.0 Licence.

What is referencedColumnName used for in JPA?

Quoting API on referencedColumnName:

The name of the column referenced by this foreign key column.

Default (only applies if single join column is being used): The same name as the primary key column of the referenced table.


Where this would be used?

When there is a composite PK in referenced table, then you need to specify column name you are referencing.

Comments in .gitignore?

Yes, you may put comments in there. They however must start at the beginning of a line.


The rules for the patterns you can put in the .gitignore file are as follows:
- Blank lines or lines starting with # are ignored.

The comment character is #, example:

# no .a files

jquery change div text

Put the title in its own span.

<span id="dialog_title_span">'+dialog_title+'</span>
$('#dialog_title_span').text("new dialog title");

How to set a timeout on a http.request() in Node?

2019 Update

There are various ways to handle this more elegantly now. Please see some other answers on this thread. Tech moves fast so answers can often become out of date fairly quickly. My answer will still work but it's worth looking at alternatives as well.

2012 Answer

Using your code, the issue is that you haven't waited for a socket to be assigned to the request before attempting to set stuff on the socket object. It's all async so:

var options = { ... }
var req = http.request(options, function(res) {
  // Usual stuff: on(data), on(end), chunks, etc...

req.on('socket', function (socket) {
    socket.on('timeout', function() {

req.on('error', function(err) {
    if (err.code === "ECONNRESET") {
        console.log("Timeout occurs");
        //specific error treatment
    //other error treatment


The 'socket' event is fired when the request is assigned a socket object.

Laravel 5.2 - Use a String as a Custom Primary Key for Eloquent Table becomes 0

I was using Postman to test my Laravel API.

I received an error that stated

"SQLSTATE[42S22]: Column not found: 1054 Unknown column" because Laravel was trying to automatically create two columns "created_at" and "updated_at".

I had to enter public $timestamps = false; to my model. Then, I tested again with Postman and saw that an "id" = 0 variable was being created in my database.

I finally had to add public $incrementing false; to fix my API.

Difference between numeric, float and decimal in SQL Server

Not a complete answer, but a useful link:

"I frequently do calculations against decimal values. In some cases casting decimal values to float ASAP, prior to any calculations, yields better accuracy. "

how to prevent css inherit

While this isn't currently available, this fascinating article discusses the use of the Shadow DOM, which is a technique used by browsers to limit how far cascading style sheets cascade, so to speak. He doesn't provide any APIs, as it seems that there are no current libraries able to provide access to this part of the DOM, but it's worth a look. There are links to mailing lists at the bottom of the article if this intrigues you.

MySQL ERROR 1045 (28000): Access denied for user 'bill'@'localhost' (using password: YES)

When you ran

mysql -u bill -p

and got this error

ERROR 1045 (28000): Access denied for user 'bill'@'localhost' (using password: YES)

mysqld is expecting you to connect as bill@localhost

Try creating bill@localhost

CREATE USER bill@localhost IDENTIFIED BY 'passpass';
grant all privileges on *.* to bill@localhost with grant option;

If you want to connect remotely, you must specify either the DNS name, the public IP, or using TCP/IP:

mysql -u bill -p [email protected]
mysql -u bill -p -h10.1.2.30
mysql -u bill -p -h127.0.0.1 --protocol=TCP

Once you login, please run this


USER() reports how you attempted to authenticate in MySQL

CURRENT_USER() reports how you were allowed to authenticate in MySQL from the mysql.user table

This will give you a better view of how and why you were allowed to login to mysql. Why is this view important to know? It has to do with the user authentication ordering protocol.

Here is an example: I will create an anonymous user on my desktop MySQL

mysql> select user,host from mysql.user;
| user    | host      |
| lwdba   | %         |
| mywife  | %         |
| lwdba   | |
| root    | |
| lwdba   | localhost |
| root    | localhost |
| vanilla | localhost |
7 rows in set (0.00 sec)

mysql> grant all on *.* to x@'%';
Query OK, 0 rows affected (0.02 sec)

mysql> select user,host from mysql.user;
| user    | host      |
| lwdba   | %         |
| mywife  | %         |
| x       | %         |
| lwdba   | |
| root    | |
| lwdba   | localhost |
| root    | localhost |
| vanilla | localhost |
8 rows in set (0.00 sec)

mysql> update mysql.user set user='' where user='x';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)

mysql> select user,host from mysql.user;
| user    | host      |
|         | %         |
| lwdba   | %         |
| mywife  | %         |
| lwdba   | |
| root    | |
| lwdba   | localhost |
| root    | localhost |
| vanilla | localhost |
8 rows in set (0.00 sec)


OK watch me login as anonymous user:

C:\MySQL_5.5.12>mysql -urol -Dtest -h127.0.0.1 --protocol=TCP
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 12
Server version: 5.5.12-log MySQL Community Server (GPL)

Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select user(),current_user();
| user()        | current_user() |
| rol@localhost | @%             |
1 row in set (0.00 sec)


Authentication ordering is very strict. It checks from the most specific to the least. I wrote about this authentiation style in the DBA StackExchange.

Don't forget to explicitly call for TCP as the protocol for mysql client when necessary.

How to Compare two Arrays are Equal using Javascript?

function isEqual(a) {
if (arrayData.length > 0) {
    for (var i in arrayData) {
        if (JSON.stringify(arrayData[i]) === JSON.stringify(a)) {
            alert("Ya existe un registro con esta informacion");
            return false;

Check this example

IOError: [Errno 2] No such file or directory trying to open a file

I got this error and fixed by appending the directory path in the loop. script not in the same directory as the files. dr1 ="~/test" directory variable


iOS 7's blurred overlay effect using CSS?

Here is my take on this with jQuery. Solution isn't universal, meaning one would have to tweak some of the positions and stuff depending on the actual design.

Basically what I did is: on trigger clone/remove the whole background (what should be blurred) to a container with unblurred content (which, optionally, has hidden overflow if it is not full width) and position it correctly. Caveat is that on window resize blurred div will mismatch the original in terms of position, but this could be solved with some on window resize function (honestly I couldn't be bothered with that now).

I would really appreciate your opinion on this solution!


Here is the fiddle, not tested in IE.


<div class="slide-up">
<div class="slide-wrapper">
    <div class="slide-background"></div>
    <div class="blured"></div>
    <div class="slide-content">
         <h2>Pop up title</h2>

        <p>Pretty neat!</p>
<div class="wrapper">
<div class="content">
     <h1>Some title</h1>
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque molestie magna elit, quis pulvinar lectus gravida sit amet. Phasellus lacinia massa et metus blandit fermentum. Cras euismod gravida scelerisque. Fusce molestie ligula diam, non porta ipsum faucibus sed. Nam interdum dui at fringilla laoreet. Donec sit amet est eu eros suscipit commodo eget vitae velit.</p>
</div> <a class="trigger" href="#">trigger slide</a>

<svg version="1.1" xmlns="">
<filter id="blur">
    <feGaussianBlur stdDeviation="3" />


body {
margin: 0;
padding: 0;
font-family:'Verdana', sans-serif;
color: #fff;
.wrapper {
position: relative;
height: 100%;
overflow: hidden;
z-index: 100;
background: #CD535B;
img {
width: 100%;
height: auto;
.blured {
top: 0;
height: 0;
-webkit-filter: blur(3px);
-moz-filter: blur(3px);
-ms-filter: blur(3px);
filter: blur(3px);
filter: url(#blur);
position: absolute;
z-index: 1000;
.blured .wrapper {
position: absolute;
width: inherit;
.content {
width: 300px;
margin: 0 auto;
.slide-up {
position: absolute;
width: 100%;
z-index: 2000;
display: none;
height: auto;
overflow: hidden;
.slide-wrapper {
width: 200px;
margin: 0 auto;
position: relative;
border: 1px solid #fff;
overflow: hidden;
.slide-content {
z-index: 2222;
position: relative;
text-align: center;
color: #333333;
.slide-background {
position: absolute;
top: 0;
width: 100%;
height: 100%;
background-color: #fff;
z-index: 1500;
opacity: 0.5;


// first just grab some pixels we will use to correctly position the blured element
var height = $('.slide-up').outerHeight();
var slide_top = parseInt($('.slide-up').css('top'), 10);
$wrapper_width = $('body > .wrapper').css("width");
$('.blured').css("width", $wrapper_width);

$('.trigger').click(function () {
    if ($(this).hasClass('triggered')) { // sliding up
            height: '0px',
            background: background
        }, 1000, function () {
            $('.blured .wrapper').remove();
    } else { // sliding down
        $offset = $('.slide-wrapper').offset();
            height: $ + height + slide_top + 'px'
        }, 700);
        $('.blured .wrapper').animate({
            left: -$offset.left,
            top: -$
        }, 100);

Difference between "this" and"super" keywords in Java

super is used to access methods of the base class while this is used to access methods of the current class.

Extending the notion, if you write super(), it refers to constructor of the base class, and if you write this(), it refers to the constructor of the very class where you are writing this code.

What does the "__block" keyword mean?

It means that the variable it is a prefix to is available to be used within a block.

How to get the <html> tag HTML with JavaScript / jQuery?

The simplest way to get the html element natively is:


Here's the reference:

UPDATE: To then grab the html element as a string you would do:


remove attribute display:none; so the item will be visible

For this particular purpose, $("span").show() should be good enough.

Path.Combine for URLs?

Recently Combine method was added to Energy.Core package, so you might want to use it to join URL parts.

    string url;
    url = Energy.Base.Url.Combine("", "watch?v=NHCgbs3TcYg");
    url = Energy.Base.Url.Combine("", "watch?v=NHCgbs3TcYg", "t=150");

Additionally it will recognize parameter part, so it will work as you might expect (joining path with slash and parameters with ampersand).

Documentation for Energy.Base.Url class

Package on NuGet gallery

Code sample

Best way to remove an event handler in jQuery?

If you use $(document).on() to add a listener to a dynamically created element then you may have to use the following to remove it:

// add the listener
    // stuff

// remove the listener
$(document).off("click", ".element");

What is the difference between primary, unique and foreign key constraints, and indexes?

Primary key mainly prevent duplication and shows the uniqueness of columns Foreign key mainly shows relationship on two tables

identifier "string" undefined?

Perhaps you wanted to #include<string>, not <string.h>. std::string also needs a namespace qualification, or an explicit using directive.

Constantly print Subprocess output while process is running

In Python 3.6 I used this:

import subprocess

cmd = "command"
output =, shell=True)

Set specific precision of a BigDecimal

Try this code ...

    Integer perc = 5;
    BigDecimal spread = BigDecimal.ZERO; 
    BigDecimal perc = spread.setScale(perc,BigDecimal.ROUND_HALF_UP);

Result: 0.00000

Increment variable value by 1 ( shell programming)

The way to use expr:

i=`expr $i + 1`

the way to use i++

((i++)); echo $i;

Tested in gnu bash

Else clause on Python while statement

The else-clause is executed when the while-condition evaluates to false.

From the documentation:

The while statement is used for repeated execution as long as an expression is true:

while_stmt ::=  "while" expression ":" suite
                ["else" ":" suite]

This repeatedly tests the expression and, if it is true, executes the first suite; if the expression is false (which may be the first time it is tested) the suite of the else clause, if present, is executed and the loop terminates.

A break statement executed in the first suite terminates the loop without executing the else clause’s suite. A continue statement executed in the first suite skips the rest of the suite and goes back to testing the expression.

Reading images in python

You can also use Pillow like this:

from PIL import Image
image ="image_path.jpg")

How to check whether a file is empty or not?

if you have the file object, then

>>> import os
>>> with open('new_file.txt') as my_file:
..., os.SEEK_END) # go to end of file
...     if my_file.tell(): # if current position is truish (i.e != 0)
... # rewind the file for later use 
...     else:
...         print "file is empty"
file is empty

How to do a recursive find/replace of a string with awk or sed?

If you do not mind using vim together with grep or find tools, you could follow up the answer given by user Gert in this link --> How to do a text replacement in a big folder hierarchy?.

Here's the deal:

  • recursively grep for the string that you want to replace in a certain path, and take only the complete path of the matching file. (that would be the $(grep 'string' 'pathname' -Rl).

  • (optional) if you want to make a pre-backup of those files on centralized directory maybe you can use this also: cp -iv $(grep 'string' 'pathname' -Rl) 'centralized-directory-pathname'

  • after that you can edit/replace at will in vim following a scheme similar to the one provided on the link given:

    • :bufdo %s#string#replacement#gc | update

Execution failed for task :':app:mergeDebugResources'. Android Studio

For me. I changed the color of .xml image (vector image) like this.


  <vector xmlns:android=""


<vector xmlns:android=""

i just changed android:fillColor="@android:color/white" to android:fillColor="#FF000000"

and it's worked for me :)

#1045 - Access denied for user 'root'@'localhost' (using password: YES)

Well, there are many solutions already given above. If there are none of them works, maybe you should just try to reset your password again to 'root' as described here, and then reopen http://localhost/phpMyAdmin/ in other browser. At least this solution works for me.

Drawing circles with System.Drawing

With this code you can easily draw a circle... C# is great and easy my friend

public partial class Form1 : Form

public Form1()

  private void button1_Click(object sender, EventArgs e)
        Graphics myGraphics = base.CreateGraphics();
        Pen myPen = new Pen(Color.Red);
        SolidBrush mySolidBrush = new SolidBrush(Color.Red);
        myGraphics.DrawEllipse(myPen, 50, 50, 150, 150);

Toad for Oracle..How to execute multiple statements?

Highlight everything you want to run and run as a script. You can do that by clicking the icon on the menu bar that looks like a text file with a lightning bolt on it. That is the same as hitting F5. So if F5 doesn't work you probably have an error in your script.

Do you have semicolons after each statement?

How to dump a table to console?

You have to code it yourself I'm afraid. I wrote this, and it may be of some use to you

function printtable(table, indent)

  indent = indent or 0;

  local keys = {};

  for k in pairs(table) do
    keys[#keys+1] = k;
    table.sort(keys, function(a, b)
      local ta, tb = type(a), type(b);
      if (ta ~= tb) then
        return ta < tb;
        return a < b;

  print(string.rep('  ', indent)..'{');
  indent = indent + 1;
  for k, v in pairs(table) do

    local key = k;
    if (type(key) == 'string') then
      if not (string.match(key, '^[A-Za-z_][0-9A-Za-z_]*$')) then
        key = "['"..key.."']";
    elseif (type(key) == 'number') then
      key = "["..key.."]";

    if (type(v) == 'table') then
      if (next(v)) then
        printf("%s%s =", string.rep('  ', indent), tostring(key));
        printtable(v, indent);
        printf("%s%s = {},", string.rep('  ', indent), tostring(key));
    elseif (type(v) == 'string') then
      printf("%s%s = %s,", string.rep('  ', indent), tostring(key), "'"..v.."'");
      printf("%s%s = %s,", string.rep('  ', indent), tostring(key), tostring(v));
  indent = indent - 1;
  print(string.rep('  ', indent)..'}');

Count the occurrences of DISTINCT values

I have resolved the same problem using the below code:

String query = "SELECT violationDate, COUNT(*) as date " +
            "FROM challan " +
            "WHERE challanType = '" + type + "' GROUP BY violationDate";

Here violationDate and date are two columns of the result table. date column will return occurrence.


How to install an APK file on an Android phone?

Directly connect your Android device and select the USB debugging option in the device. Eclipse will itself find your device, and then just run the code.

Or alternatively, paste your APK file in the Android SDK platform-tools folder and from the command prompt install it like this:

D:......../platform-tools> adb install yourfile.apk.

How to make google spreadsheet refresh itself every 1 minute?

GOOGLEFINANCE can have a 20 minutes delay, so refreshing every minute would not really help.

Instead of GOOGLEFINANCE you can use different source. I'm using this RealTime stock prices(I tried a couple but this is the easiest by-far to implement. They have API that retuen JSON { Name: CurrentPrice }

Here's a little script you can use in Google Sheets(Tools->Script Editor)

function GetStocksPrice() {      
   var url = ' 
   var response = UrlFetchApp.fetch(url);

   // convert json string to json object
   var jsonSignal = JSON.parse(response);    

  // define an array of all the object keys
  var headerRow = Object.keys(jsonSignal);
  // define an array of all the object values
  var values ={ return jsonSignal[key]});   
  var data = values[0];

  // get sheet by ID -  
  // you can get the sheet unqiue ID from the your current sheet url
  var jsonSheet = SpreadsheetApp.openById("Your Sheet UniqueID");  
  //var name = jsonSheet.getName();

  var sheet = jsonSheet.getSheetByName('Sheet1'); 

  // the column to put the data in -> Y
  var letter = "F";

  // start from line 
  var index = 4;
  data.forEach(function( row, index2 ) { 

     var keys = Object.keys(row);
     var value2 = row[keys[1]];            

     // set value loction
     var cellXY = letter +  index;      
     index = index + 1;    

Now you need to add a trigger that will execute every minute.

  1. Go to Project Triggers -> click on the Watch icon next to the Save icon
  2. Add Trigger
  3. In -> Choose which function to run -> GetStocksPrice
  4. In -> Select event source -> Time-driven
  5. In -> Select type of time based trigger -> Minutes timer
  6. In -> Select minute interval -> Every minute

And your set :)

How to turn on/off MySQL strict mode in localhost (xampp)?

on Debian 10 I start mysql from ./opt/lampp/xampp start

I do strace ./opt/lampp/sbin/mysqld and see that my.cnf is there:

stat("/opt/lampp/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=5050, ...}) = 0
openat(AT_FDCWD, "/opt/lampp/etc/my.cnf", O_RDONLY|O_CLOEXEC) = 3

hence, I add sql_mode config to /opt/lampp/etc/my.cnf instead of /etc/mysql/my.cnf

How to uninstall a windows service and delete its files without rebooting

I am using the InstallUtil.exe packed with .NET Framework.

The usage to uninstall is: InstallUtil '\path\to\assembly\with\the\installer\classes' /u so for example: installutil MyService.HostService.exe /u

The /u switch stands for uninstall, without it the util performs normal installation of the service. The utility stops the service if it is running and I never had problems with Windows keeping lock on the service files. You can read about other options of InstallUtil on MSDN.

P.S.:if you don't have installutil in your path variable use full path like this: C:\Windows\Microsoft.NET\Framework\v4.0.30319\InstallUtil.exe "C:\MyServiceFolder\MyService.HostService.exe" /u or if you need 64bit version it can be found in 'C:\Windows\Microsoft.NET\Framework64\v4.0.30319\' .The version number in path varies depending on .NET version.

Insert line break in wrapped cell via code

Yes. The VBA equivalent of AltEnter is to use a linebreak character:

ActiveCell.Value = "I am a " & Chr(10) & "test"

Note that this automatically sets WrapText to True.


Sub test()
Dim c As Range
Set c = ActiveCell
c.WrapText = False
MsgBox "Activcell WrapText is " & c.WrapText
c.Value = "I am a " & Chr(10) & "test"
MsgBox "Activcell WrapText is " & c.WrapText
End Sub

What are the main differences between JWT and OAuth authentication?

JWT is an open standard that defines a compact and self-contained way for securely transmitting information between parties. It is an authentication protocol where we allow encoded claims (tokens) to be transferred between two parties (client and server) and the token is issued upon the identification of a client. With each subsequent request we send the token.

Whereas OAuth2 is an authorization framework, where it has a general procedures and setups defined by the framework. JWT can be used as a mechanism inside OAuth2.

You can read more on this here

OAuth or JWT? Which one to use and why?

TypeError: 'str' does not support the buffer interface

>>> s = bytes("s","utf-8")
>>> print(s)
>>> s = s.decode("utf-8")
>>> print(s)

Well if useful for you in case removing annoying 'b' character.If anyone got better idea please suggest me or feel free to edit me anytime in here.I'm just newbie

How to "flatten" a multi-dimensional array to simple one in PHP?

A non-recursive solution (but order-destroying):

function flatten($ar) {
    $toflat = array($ar);
    $res = array();

    while (($r = array_shift($toflat)) !== NULL) {
        foreach ($r as $v) {
            if (is_array($v)) {
                $toflat[] = $v;
            } else {
                $res[] = $v;

    return $res;

Is it possible to change the location of packages for NuGet?

In addition to Shane Kms answer, if you've activated Nuget Package Restore, you edit the NuGet.config located in the .nuget-folder as follows:

<?xml version="1.0" encoding="utf-8"?>

Notice the extra "..\", as it backtracks from the .nuget-folder and not the solution folder.

how to end ng serve or firebase serve

----Ctrl + c then choose Y from the Y/N option provided.

What would be the best method to code heading/title for <ul> or <ol>, Like we have <caption> in <table>?

Would the use of <caption> be allowed?

  <caption> Title of List </caption>
  <li> Item 1 </li>
  <li> Item 2 </li>

How to remove margin space around body or clear default css styles

try to ad the following in your CSS:

body, html{

How can I set / change DNS using the command-prompt at windows 8

Now you can change the primary dns (index=1), assuming that your interface is static (not using dhcp)

You can set your DNS servers statically even if you use DHCP to obtain your IP address.

Example under Windows 7 to add two DN servers, the command is as follows:

netsh interface ipv4 add dns "Local Area Connection" address=192.168.x.x index=1 netsh interface ipv4 add dns "Local Area Connection" address=192.168.x.x index=2

Javascript-Setting background image of a DIV via a function and function parameter

You need to concatenate your string.

document.getElementById(tabName).style.backgroundImage = 'url(buttons/' + imagePrefix + '.png)';

The way you had it, it's just making 1 long string and not actually interpreting imagePrefix.

I would even suggest creating the string separate:

function ChangeBackgroungImageOfTab(tabName, imagePrefix)
    var urlString = 'url(buttons/' + imagePrefix + '.png)';
    document.getElementById(tabName).style.backgroundImage =  urlString;

As mentioned by David Thomas below, you can ditch the double quotes in your string. Here is a little article to get a better idea of how strings and quotes/double quotes are related:

error running apache after xampp install server certificate does NOT include an ID which matches the server name

I was getting this error when trying to start Apache, there is no error with Apache. It's an dependency error on windows 8 - probably the same for 7. Just right click and run as Admin :)

If you're still getting an error check your Antivirus/Firewall is not blocking Xampp or port 443.

What special characters must be escaped in regular expressions?

Which characters you must and which you mustn't escape indeed depends on the regex flavor you're working with.

For PCRE, and most other so-called Perl-compatible flavors, escape these outside character classes:


and these inside character classes:


For POSIX extended regexes (ERE), escape these outside character classes (same as PCRE):


Escaping any other characters is an error with POSIX ERE.

Inside character classes, the backslash is a literal character in POSIX regular expressions. You cannot use it to escape anything. You have to use "clever placement" if you want to include character class metacharacters as literals. Put the ^ anywhere except at the start, the ] at the start, and the - at the start or the end of the character class to match these literally, e.g.:


In POSIX basic regular expressions (BRE), these are metacharacters that you need to escape to suppress their meaning:


Escaping parentheses and curly brackets in BREs gives them the special meaning their unescaped versions have in EREs. Some implementations (e.g. GNU) also give special meaning to other characters when escaped, such as \? and +. Escaping a character other than .^$*(){} is normally an error with BREs.

Inside character classes, BREs follow the same rule as EREs.

If all this makes your head spin, grab a copy of RegexBuddy. On the Create tab, click Insert Token, and then Literal. RegexBuddy will add escapes as needed.

PHP - add 1 day to date format mm-dd-yyyy

$date = DateTime::createFromFormat('m-d-Y', '04-15-2013');
$date->modify('+1 day');
echo $date->format('m-d-Y');

See it in action

Or in PHP 5.4+

echo (DateTime::createFromFormat('m-d-Y', '04-15-2013'))->modify('+1 day')->format('m-d-Y');


Joda DateTime to Timestamp conversion

Actually this is not a duplicate question. And this how i solve my problem after several times :

   int offset = DateTimeZone.forID("anytimezone").getOffset(new DateTime());

This is the way to get offset from desired timezone.

Let's return to our code, we were getting timestamp from a result set of query, and using it with timezone to create our datetime.

   DateTime dt = new DateTime(rs.getTimestamp("anytimestampcolumn"),

Now we will add our offset to the datetime, and get the timestamp from it.

    dt = dt.plusMillis(offset);
    Timestamp ts = new Timestamp(dt.getMillis());

May be this is not the actual way to get it, but it solves my case. I hope it helps anyone who is stuck here.

onchange event for html.dropdownlist

If you don't want jquery then you can do it with javascript :-

@Html.DropDownList("Sortby", new SelectListItem[] 
     new SelectListItem() { Text = "Newest to Oldest", Value = "0" }, 
     new SelectListItem() { Text = "Oldest to Newest", Value = "1" }},
     new { @onchange="callChangefunc(this.value)" 

    function callChangefunc(val){
        window.location.href = "/Controller/ActionMethod?value=" + val;

if block inside echo statement?

You will want to use the a ternary operator which acts as a shortened IF/Else statement:

echo '<option value="'.$value.'" '.(($value=='United States')?'selected="selected"':"").'>'.$value.'</option>';

How can I generate a list of files with their absolute path in Linux?

If you give find an absolute path to start with, it will print absolute paths. For instance, to find all .htaccess files in the current directory:

find "$(pwd)" -name .htaccess

or if your shell expands $PWD to the current directory:

find "$PWD" -name .htaccess

find simply prepends the path it was given to a relative path to the file from that path.

Greg Hewgill also suggested using pwd -P if you want to resolve symlinks in your current directory.

Insert PHP code In WordPress Page and Post

When I was trying to accomplish something very similar, I ended up doing something along these lines:


add_action('init', 'my_php_function');
function my_php_function() {
    if (stripos($_SERVER['REQUEST_URI'], 'page-with-custom-php') !== false) {
        // add desired php code here

How to access cookies in AngularJS?

The original accepted answer mentions jquery.cookie plugin. A few months ago though, it was renamed to js-cookie and the jQuery dependency removed. One of the reasons was just to make it easy to integrate with other frameworks, like Angular.

Now, if you want to integrate js-cookie with angular, it is as easy as something like:

module.factory( "cookies", function() {
  return Cookies.noConflict();

And that's it. No jQuery. No ngCookies.

You can also create custom instances to handle specific server-side cookies that are written differently. Take for example PHP, that convert the spaces in the server-side to a plus sign + instead of also percent-encode it:

module.factory( "phpCookies", function() {
  return Cookies
    .withConverter(function( value, name ) {
      return value
            // Decode all characters according to the "encodeURIComponent" spec
            .replace(/(%[0-9A-Z]{2})+/g, decodeURIComponent)
            // Decode the plus sign to spaces
            .replace(/\+/g, ' ')

The usage for a custom Provider would be something like this:

module.service( "customDataStore", [ "phpCookies", function( phpCookies ) {
  this.storeData = function( data ) {
    phpCookies.set( "data", data );
  this.containsStoredData = function() {
    return phpCookies.get( "data" );

I hope this helps anyone.

See detailed info in this issue:

For detailed docs on how to integrate with server-side, see here:

How to insert close button in popover for Bootstrap

The trick is to get the current Popover with .data('bs.popover').tip():

$('#my_trigger').popover().on('', function() {
    // Define elements
    var current_trigger=$(this);

    // Activate close button
    current_popover.find('button.close').click(function() {

How to negate a method reference predicate

Shouldn't Predicate#negate be what you are looking for?

Can I return the 'id' field after a LINQ insert?

Try this:

MyContext Context = new MyContext(); 
int ID = obj._ID;

Where can I find a NuGet package for upgrading to System.Web.Http v5.0.0.0?

I have several projects in a solution. For some of the projects, I previously added the references manually. When I used NuGet to update the WebAPI package, those references were not updated automatically.

I found out that I can either manually update those reference so they point to the v5 DLL inside the Packages folder of my solution or do the following.

  1. Go to the "Manage NuGet Packages"
  2. Select the Installed Package "Microsoft ASP.NET Web API 2.1"
  3. Click Manage and check the projects that I manually added before.

Pythonic way to add and datetime.time objects

It's in the python docs.

import datetime
datetime.datetime.combine(, 1, 1), 
                          datetime.time(10, 23))


datetime.datetime(2011, 1, 1, 10, 23)

How do you round a number to two decimal places in C#?

Math.Floor(123456.646 * 100) / 100 Would return 123456.64

How can I get the list of files in a directory using C or C++?

GNU Manual FTW

Also, sometimes it's good to go right to the source (pun intended). You can learn a lot by looking at the innards of some of the most common commands in Linux. I've set up a simple mirror of GNU's coreutils on github (for reading).

Maybe this doesn't address Windows, but a number of cases of using Unix variants can be had by using these methods.

Hope that helps...

Changing the image source using jQuery

You can use jQuery's attr() function. For example, if your img tag has an id attribute of 'my_image', you would do this:

<img id="my_image" src="first.jpg"/>

Then you can change the src of your image with jQuery like this:


To attach this to a click event, you could write:

    'click': function(){

To rotate the image, you could do this:

    'click': function() {
         var src = ($(this).attr('src') === 'img1_on.jpg')
            ? 'img2_on.jpg'
            : 'img1_on.jpg';
         $(this).attr('src', src);

PHP - concatenate or directly insert variables in string

From the point of view of making thinks simple, readable, consistent and easy to understand (since performance doesn't matter here):

  • Using embedded vars in double quotes can lead to complex and confusing situations when you want to embed object properties, multidimentional arrays etc. That is, generally when reading embedded vars, you cannot be instantly 100% sure of the final behavior of what you are reading.

  • You frequently need add crutches such as {} and \, which IMO adds confusion and makes concatenation readability nearly equivalent, if not better.

  • As soon as you need to wrap a function call around the var, for example htmlspecialchars($var), you have to switch to concatenation.

  • AFAIK, you cannot embed constants.

In some specific cases, "double quotes with vars embedding" can be useful, but generally speaking, I would go for concatenation (using single or double quotes when convenient)

How to use lifecycle method getDerivedStateFromProps as opposed to componentWillReceiveProps

As mentioned by Dan Abramov

Do it right inside render

We actually use that approach with memoise one for any kind of proxying props to state calculations.

Our code looks this way

// ./decorators/memoized.js  
import memoizeOne from 'memoize-one';

export function memoized(target, key, descriptor) {
  descriptor.value = memoizeOne(descriptor.value);
  return descriptor;

// ./components/exampleComponent.js
import React from 'react';
import { memoized } from 'src/decorators';

class ExampleComponent extends React.Component {
  buildValuesFromProps() {
    const {
    } = this.props
    return {
      value1: buildValue1(watchedProp1, watchedProp2),
      value2: buildValue2(watchedProp1, watchedProp3, watchedProp5),
      value3: buildValue3(watchedProp3, watchedProp4, watchedProp5),

  buildValue1(watchedProp1, watchedProp2) {
    return ...;

  buildValue2(watchedProp1, watchedProp3, watchedProp5) {
    return ...;

  buildValue3(watchedProp3, watchedProp4, watchedProp5) {
    return ...;

  render() {
    const {
    } = this.buildValuesFromProps();

    return (
        <Component1 value={value1}>
        <Component2 value={value2}>
        <Component3 value={value3}>

The benefits of it are that you don't need to code tons of comparison boilerplate inside getDerivedStateFromProps or componentWillReceiveProps and you can skip copy-paste initialization inside a constructor.


This approach is used only for proxying the props to state, in case you have some inner state logic it still needs to be handled in component lifecycles.

select the TOP N rows from a table

select * from table_name LIMIT 100

remember this only works with MYSQL

How to force open links in Chrome not download them?

To make certain file types OPEN on your computer, instead of Chrome Downloading...

You have to download the file type once, then right after that download, look at the status bar at the bottom of the browser. Click the arrow next to that file and choose "always open files of this type". DONE.

Now the file type will always OPEN using your default program.

To reset this feature, go to Settings / Advance Settings and under the "Download.." section, there's a button to reset 'all' Auto Downloads

Hope this helps.. :-)

Visual Instructions found here:

Chrome: Uncaught SyntaxError: Unexpected end of input

Since it's an async operation the onreadystatechange may happen before the value has loaded in the responseText, try using a window.setTimeout(function () { JSON.parse(xhr.responseText); }, 1000); to see if the error persists? BOL

python ignore certificate validation urllib2

The easiest way:

python 2

import urllib2, ssl

request = urllib2.Request('')
response = urllib2.urlopen(request, context=ssl._create_unverified_context())

python 3

from urllib.request import urlopen
import ssl

response = urlopen('', context=ssl._create_unverified_context())

urllib2.HTTPError: HTTP Error 403: Forbidden

This will work in Python 3

import urllib.request

user_agent = 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv: Gecko/2009021910 Firefox/3.0.7'

url = ""

request=urllib.request.Request(url,None,headers) #The assembled request
response = urllib.request.urlopen(request)
data = # The data u need

Getting the names of all files in a directory with PHP

As the accepted answer has two important shortfalls, I'm posting the improved answer for those new comers who are looking for a correct answer:

foreach (array_filter(glob('/Path/To/*'), 'is_file') as $file)
    // Do something with $file
  1. Filtering the globe function results with is_file is necessary, because it might return some directories as well.
  2. Not all files have a . in their names, so */* pattern sucks in general.

How do I extend a class with c# extension methods?

The closest I can get to the answer is by adding an extension method into a System.Type object. Not pretty, but still interesting.

public static class Foo
    public static void Bar()
        var now = DateTime.Now;
        var tomorrow = typeof(DateTime).Tomorrow();

    public static DateTime Tomorrow(this System.Type type)
        if (type == typeof(DateTime)) {
            return DateTime.Now.AddDays(1);
        } else {
            throw new InvalidOperationException();

Otherwise, IMO Andrew and ShuggyCoUk has a better implementation.

How do I display a ratio in Excel in the format A:B?

The second formula on that page uses the GCD function of the Analysis ToolPak, you can add it from Tools > Add-Ins.


This is a more mathematical formula rather than a text manipulation based on.

Execute jQuery function after another function completes

Deferred promises are a nice way to chain together function execution neatly and easily. Whether AJAX or normal functions, they offer greater flexibility than callbacks, and I've found easier to grasp.

function Typer()
var dfd = $.Deferred();
    var srcText = 'EXAMPLE ';
    var i = 0;
    var result = srcText[i];



  var timer=    setInterval(function() {
                    if(i == srcText.length) {

    // clearInterval(this);



                        result += srcText[i].replace("\n", "<br />");
                        $("#message").html( result);
              return dfd.promise();

I've modified the play function so it returns a promise when the audio finishes playing, which might be useful to some. The third function fires when sound finishes playing.

   function playBGM()
      var playsound = $.Deferred();
      $("#bgm").on("ended", function() {
        return playsound.promise();

    function thirdFunction() {
        alert('third function');

Now call the whole thing with the following: (be sure to use Jquery 1.9.1 or above as I found that 1.7.2 executes all the functions at once, rather than waiting for each to resolve.)


Before today, I had no luck using deferred promises in this way, and finally have grasped it. Precisely timed, chained interface events occurring exactly when we want them to, including async events, has never been easy. For me at least, I now have it under control thanks largely to others asking questions here.

Using a batch to copy from network drive to C: or D: drive

Most importantly you need to mount the drive

net use z: \\yourserver\sharename

Of course, you need to make sure that the account the batch file runs under has permission to access the share. If you are doing this by using a Scheduled Task, you can choose the account by selecting the task, then:

  • right click Properties
  • click on General tab
  • change account under

"When running the task, use the following user account:" That's on Windows 7, it might be slightly different on different versions of Windows.

Then run your batch script with the following changes

copy "z:\FolderName" "C:\TEST_BACKUP_FOLDER"

Set The Window Position of an application via command line

Bill K.'s answer was the most elegant if you just want to start a window at startup or start from a shortcut on the desktop.

Just open the window where you want it, right click and choose properties. select Layout uncheck "let system position window" and click OK.

Window will now open just where you want it. You can set font and window colors at the same time on other tabs. sweet.

Choose newline character in Notepad++

on windows 10, Notepad 7.8.5, i found this solution to convert from CRLF to LF.
Edit > Format end of line
and choose either Windows(CR+LF) or Unix(LF)

jQuery ajax upload file in mvc

You can't upload files via ajax, you need to use an iFrame or some other trickery to do a full postback. This is mainly due to security concerns.

Here's a decent write-up including a sample project using SWFUpload and ASP.Net MVC by Steve Sanderson. It's the first thing I read getting this working properly with Asp.Net MVC (I was new to MVC at the time as well), hopefully it's as helpful for you.

'this' vs $scope in AngularJS controllers

$scope has a different 'this' then the controller 'this'.Thus if you put a console.log(this) inside controller it gives you a object(controller) and this.addPane() adds addPane Method to the controller Object. But the $scope has different scope and all method in its scope need to be accesed by $scope.methodName(). this.methodName() inside controller means to add methos inside controller object.$scope.functionName() is in HTML and inside

    $scope.myname="myname"//are same}

Paste this code in your editor and open console to see...

 <!DOCTYPE html>
<html lang="en">
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>this $sope vs controller</title>
<script src=""></script>
        var app=angular.module("myApp",[]);
          console.log("ctrl 'this'",this);
          //this(object) of controller different then $scope

            console.log("controllerMethod ",this);
              console.log("$scope 'this",this);
              //this of $scope
              $scope.message="Welcome User";

<body ng-app="myApp" >
<div ng-controller="ctrlExample">
       Comming From $SCOPE :{{firstName}}
       Comming from $SCOPE:{{lastName}}
       Should Come From Controller:{{nickName}}
            Blank nickName is because nickName is attached to 
           'this' of controller.

       <button ng-click="controllerMethod()">Controller Method</button>

       <button ng-click="show()">Show</button>



Delete specific line from a text file?

Are you on a Unix operating system?

You can do this with the "sed" stream editor. Read the man page for "sed"

JavaScript: How to join / combine two arrays to concatenate into one array?

var a = ['a','b','c'];
var b = ['d','e','f'];
var c = a.concat(b); //c is now an an array with: ['a','b','c','d','e','f']
console.log( c[3] ); //c[3] will be 'd'

How to hide Bootstrap previous modal when you opening new one?

The best that I've been able to do is


This gets the modal holding the DOM object you triggered the event on (guessing you're clicking a button). Gets the closest parent '.modal' and toggles it. Obviously only works because it's inside the modal you clicked.

You can however do this:


This gets the modal that is displaying (since you can only have one open at a time), and triggers the 'toggle' This would not work without ":visible"

How to check if a file exists in a folder?

This way we can check for an existing file in a particular folder:

 string curFile = @"c:\temp\test.txt";  //Your path
 Console.WriteLine(File.Exists(curFile) ? "File exists." : "File does not exist.");

Bootstrap dropdown menu not working (not dropping down when clicked)

Just Remove the type="text/javascript"

<script src="JavaScript/jquery.js" />
<script src="JavaScript/bootstrap-min.js" />

Here is the update -

How do you install Boost on MacOS?

Unless your compiler is different than the one supplied with the Mac XCode Dev tools, just follow the instructions in section 5.1 of Getting Started Guide for Unix Variants. The configuration and building of the latest source couldn't be easier, and it took all about about 1 minute to configure and 10 minutes to compile.

How to return images in flask response?

You use something like

from flask import send_file

def get_image():
    if request.args.get('type') == '1':
       filename = 'ok.gif'
       filename = 'error.gif'
    return send_file(filename, mimetype='image/gif')

to send back ok.gif or error.gif, depending on the type query parameter. See the documentation for the send_file function and the request object for more information.

Generate a random number in a certain range in MATLAB

Best solution is randint , but this function produce integer numbers.

You can use rand with rounding function

  r = round(a + (b-a).*rand(m,n));

This produces Real random number between a and b , size of output matrix is m*n

Ignore cells on Excel line graph

if the data is the result of a formula, then it will never be empty (even if you set it to ""), as having a formula is not the same as an empty cell

There are 2 methods, depending on how static the data is.

The easiest fix is to clear the cells that return empty strings, but that means you will have to fix things if data changes

the other fix involves a little editing of the formula, so instead of setting it equal to "", you set it equal to NA().
For example, if you have =IF(A1=0,"",B1/A1), you would change that to =IF(A1=0,NA(),B1/A1).
This will create the gaps you desire, and will also reflect updates to the data so you don't have to keep fixing it every time

How to flush output after each `echo` call?

One thing that is not often mentionned is gzip compression that keeps turned ON because of details in various hosting environments.

Here is a modern approach, working with PHP-FPM as Fast CGI, which does not need .htaccess rewrite rule or environment variable :

In php.ini or .user.ini :

output_buffering = 0
zlib.output_compression = 0
implicit_flush = true
output_handler = 

In PHP script :

header('Content-Encoding: none'); // Disable gzip compression
ob_end_flush(); // Stop buffer
ob_implicit_flush(1); // Implicit flush at each output command

See this comment on official PHP doc for ob_end_flush() need.

EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0) on dispatch_semaphore_dispose

In my case:

PHImageRequestOptions *requestOptions = [PHImageRequestOptions new];
requestOptions.synchronous            = NO;

Was trying to do this with dispatch_group

PNG transparency issue in IE8

Dan Tello fix worked well for me.

One additional issue I found with IE8 was that if the PNG was held in a DIV with smaller CSS width or height dimensions than the PNG then the black edge prob was re-triggered.

Correcting the width and height CSS or removing them altogether fixed.

Should I initialize variable within constructor or outside constructor

I find the second style (declaration + initialization in one go) superior. Reasons:

  • It makes it clear at a glance how the variable is initialized. Typically, when reading a program and coming across a variable, you'll first go to its declaration (often automatic in IDEs). With style 2, you see the default value right away. With style 1, you need to look at the constructor as well.
  • If you have more than one constructor, you don't have to repeat the initializations (and you cannot forget them).

Of course, if the initialization value is different in different constructors (or even calculated in the constructor), you must do it in the constructor.

How to dynamically create generic C# object using reflection?

Make sure you're doing this for a good reason, a simple function like the following would allow static typing and allows your IDE to do things like "Find References" and Refactor -> Rename.

public Task <T> factory (String name)
  Task <T> result;

  if (name.CompareTo ("A") == 0)
    result = new TaskA ();
  else if (name.CompareTo ("B") == 0)
    result = new TaskB ();

  return result;

How to download files using axios

This Worked for me. i implemented this solution in reactJS

const requestOptions = {`enter code here`
method: 'GET',
headers: { 'Content-Type': 'application/json' }

fetch(`${url}`, requestOptions)
.then((res) => {
    return res.blob();
.then((blob) => {
    const href = window.URL.createObjectURL(blob);
    const link = document.createElement('a');
    link.href = href;
    link.setAttribute('download', 'config.json'); //or any other extension
.catch((err) => {
    return Promise.reject({ Error: 'Something Went Wrong', err });

Creating a new DOM element from an HTML string using built-in DOM methods or Prototype

Why don't do with native js?

    var s="<span class='text-muted' style='font-size:.75em; position:absolute; bottom:3px; left:30px'>From <strong>Dan's Tools</strong></span>"
    var e=document.createElement('div')
    var r=document.createRange();
    var f=r.createContextualFragment(s);
    e = e.firstElementChild;

How to copy a file to a remote server in Python using SCP or SSH?

You can call the scp bash command (it copies files over SSH) with

import subprocess["scp", FILE, "USER@SERVER:PATH"])
#e.g.["scp", "", "[email protected]:/path/to/"])

If you're creating the file that you want to send in the same Python program, you'll want to call command outside the with block you're using to open the file (or call .close() on the file first if you're not using a with block), so you know it's flushed to disk from Python.

You need to generate (on the source machine) and install (on the destination machine) an ssh key beforehand so that the scp automatically gets authenticated with your public ssh key (in other words, so your script doesn't ask for a password).

Run a controller function whenever a view is opened/shown

Why don't you disable the view cache with cache-view="false"?

In your view add this to the ion-nav-view like that:

<ion-nav-view name="other" cache-view="false"></ion-nav-view>

Or in your stateProvider:

$stateProvider.state('other', {
   cache: false,
   url : '/other',
   templateUrl : 'templates/other/other.html'

Either one will make your controller being called always.

What is an ORM, how does it work, and how should I use one?

Can anyone give me a brief explanation...


ORM stands for "Object to Relational Mapping" where

  • The Object part is the one you use with your programming language ( python in this case )

  • The Relational part is a Relational Database Manager System ( A database that is ) there are other types of databases but the most popular is relational ( you know tables, columns, pk fk etc eg Oracle MySQL, MS-SQL )

  • And finally the Mapping part is where you do a bridge between your objects and your tables.

In applications where you don't use a ORM framework you do this by hand. Using an ORM framework would allow you do reduce the boilerplate needed to create the solution.

So let's say you have this object.

 class Employee:
      def __init__( self, name ): 
          self.__name = name

       def getName( self ):
           return self.__name


and the table

   create table employee(
          name varcar(10),
          -- etc  

Using an ORM framework would allow you to map that object with a db record automagically and write something like:

   emp = Employee("Ryan") emp )

And have the employee inserted into the DB.

Oops it was not that brief but I hope it is simple enough to catch other articles you read.

How can I get Git to follow symlinks?

I got tired of every solution in here either being outdated or requiring root, so I made an LD_PRELOAD-based solution (Linux only).

It hooks into Git's internals, overriding the 'is this a symlink?' function, allowing symlinks to be treated as their contents. By default, all links to outside the repo are inlined; see the link for details.

What is the technology behind wechat, whatsapp and other messenger apps?

WhatsApp has chosen Erlang a language built for writing scalable applications that are designed to withstand errors. Erlang uses an abstraction called the Actor model for it's concurrency - Instead of the more traditional shared memory approach, actors communicate by sending each other messages. Actors unlike threads are designed to be lightweight. Actors could be on the same machine or on different machines and the message passing abstractions works for both. A simple implementation of WhatsApp could be: Each user/device is represented as an actor. This actor is responsible for handling the inbox of the user, how it gets serialized to disk, the messages that the user sends and the messages that the user receives. Let's assume that Alice and Bob are friends on WhatsApp. So there is an an Alice actor and a Bob actor.

Let's trace a series of messages flowing back and forth:

Alice decides to message Bob. Alice's phone establishes a connection to the WhatsApp server and it is established that this connection is definitely from Alice's phone. Alice now sends via TCP the following message: "For Bob: A giant monster is attacking the Golden Gate Bridge". One of the WhatsApp front end server deserializes this message and delivers this message to the actor called Alice.

Alice the actor decides to serialize this and store it in a file called "Alice's Sent Messages", stored on a replicated file system to prevent data loss due to unpredictable monster rampage. Alice the actor then decides to forward this message to Bob the actor by passing it a message "Msg1 from Alice: A giant monster is attacking the Golden Gate Bridge". Alice the actor can retry with exponential back-off till Bob the actor acknowledges receiving the message.

Bob the actor eventually receives the message from (2) and decides to store this message in a file called "Bob's Inbox". Once it has stored this message durably Bob the actor will acknowledge receiving the message by sending Alice the actor a message of it's own saying "I received Msg1". Alice the actor can now stop it's retry efforts. Bob the actor then checks to see if Bob's phone has an active connection to the server. It does and so Bob the actor streams this message to the device via TCP.

Bob sees this message and replies with "For Alice: Let's create giant robots to fight them". This is now received by Bob the actor as outlined in Step 1. Bob the actor then repeats Step 2 and 3 to make sure Alice eventually receives the idea that will save mankind.

WhatsApp actually uses the XMPP protocol instead of the vastly superior protocol that I outlined above, but you get the point.

How to select the first element in the dropdown using jquery?

Your selector is wrong, you were probably looking for

$('select option:nth-child(1)')

This will work also:

$('select option:first-child')

Mockito : doAnswer Vs thenReturn

doAnswer and thenReturn do the same thing if:

  1. You are using Mock, not Spy
  2. The method you're stubbing is returning a value, not a void method.

Let's mock this BookService

public interface BookService {
    String getAuthor();
    void queryBookTitle(BookServiceCallback callback);

You can stub getAuthor() using doAnswer and thenReturn.

BookService service = mock(BookService.class);
// or..
doAnswer(new Answer() {
    public Object answer(InvocationOnMock invocation) throws Throwable {
        return "Joshua";

Note that when using doAnswer, you can't pass a method on when.

// Will throw UnfinishedStubbingException
doAnswer(invocation -> "Joshua").when(service.getAuthor());

So, when would you use doAnswer instead of thenReturn? I can think of two use cases:

  1. When you want to "stub" void method.

Using doAnswer you can do some additionals actions upon method invocation. For example, trigger a callback on queryBookTitle.

BookServiceCallback callback = new BookServiceCallback() {
    public void onSuccess(String bookTitle) {
        assertEquals("Effective Java", bookTitle);
doAnswer(new Answer() {
    public Object answer(InvocationOnMock invocation) throws Throwable {
        BookServiceCallback callback = (BookServiceCallback) invocation.getArguments()[0];
        callback.onSuccess("Effective Java");
        // return null because queryBookTitle is void
        return null;
  1. When you are using Spy instead of Mock

When using when-thenReturn on Spy Mockito will call real method and then stub your answer. This can cause a problem if you don't want to call real method, like in this sample:

List list = new LinkedList();
List spy = spy(list);
// Will throw java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
assertEquals("java", spy.get(0));

Using doAnswer we can stub it safely.

List list = new LinkedList();
List spy = spy(list);
doAnswer(invocation -> "java").when(spy).get(0);
assertEquals("java", spy.get(0));

Actually, if you don't want to do additional actions upon method invocation, you can just use doReturn.

List list = new LinkedList();
List spy = spy(list);
assertEquals("java", spy.get(0));

SameSite warning Chrome 77

I had to disable this in chrome://flags

enter image description here

Display A Popup Only Once Per User

Offering a quick answer for people using Ionic. I need to show a tooltip only once so I used the $localStorage to achieve this. This is for playing a track, so when they push play, it shows the tooltip once.

$ = $localStorage; //connects an object to $localstorage

$ = "false";  // they haven't seen it

$scope.showPopup = function() {  // popup to tell people to turn sound on

    $ = {}
    // An elaborate, custom popup
    var myPopup = ${
        template: '<p class="popuptext">Turn Sound On!</p>',
        cssClass: 'popup'

    $timeout(function() {
        myPopup.close(); //close the popup after 3 seconds for some reason
    }, 2000);
    $ = "true"; // they've now seen it


$scope.playStream = function(show) {;

    $scope.audioObject = audioObject; // this allow for styling the play/pause icons

    if ($ === "false"){ //only show if they haven't seen it.

How to download Visual Studio 2017 Community Edition for offline installation?

All I wanted were 1) English only and 2) just enough to build a legacy desktop project written in C. No Azure, no mobile development, no .NET, and no other components that I don't know what to do with.

[Note: Options are in multiple lines for readability, but they should be in 1 line]
    --lang en-US
    --layout ".\Visual Studio Cummunity 2017"
    --add Microsoft.VisualStudio.Workload.NativeDesktop 

I chose "NativeDesktop" from "workload and component ID" site (

The result was about 1.6GB downloaded files and 5GB when installed. I'm sure I could have removed a few unnecessary components to save space, but the list was rather long, so I stopped there.

"--includeRecommended" was the key ingredient for me, which included Windows SDK along with other essential things for building the legacy project.

Warning: mysql_fetch_array() expects parameter 1 to be resource, boolean given in

The code you have posted doesn't include a call to mysql_fetch_array(). However, what is most likely going wrong is that you are issuing a query that returns an error message, in which case the return value from the query function is false, and attempting to call mysql_fetch_array() on it doesn't work (because boolean false is not a mysql result object).

How do I find all the files that were created today in Unix/Linux?

Just keep in mind there are 2 spaces between Aug and 26. Other wise your find command will not work.

find . -type f -exec ls -l {} \; |  egrep "Aug 26";

PHP PDO with foreach and fetch

$users = $dbh->query($sql);
foreach ($users as $row) {
    print $row["name"] . "-" . $row["sex"] ."<br/>";
foreach ($users as $row) {
    print $row["name"] . "-" . $row["sex"] ."<br/>";

Here $users is a PDOStatement object over which you can iterate. The first iteration outputs all results, the second does nothing since you can only iterate over the result once. That's because the data is being streamed from the database and iterating over the result with foreach is essentially shorthand for:

while ($row = $users->fetch()) ...

Once you've completed that loop, you need to reset the cursor on the database side before you can loop over it again.

$users = $dbh->query($sql);
foreach ($users as $row) {
    print $row["name"] . "-" . $row["sex"] ."<br/>";
echo "<br/>";
$result = $users->fetch(PDO::FETCH_ASSOC);
foreach($result as $key => $value) {
    echo $key . "-" . $value . "<br/>";

Here all results are being output by the first loop. The call to fetch will return false, since you have already exhausted the result set (see above), so you get an error trying to loop over false.

In the last example you are simply fetching the first result row and are looping over it.

dlib installation on Windows 10

You have to install cmake as the error tells you.

you can follow this instructions

or directly install cmake from here

Once cmake is installed pip install dlib should work.

I had vstudio building tools installed whe I did my test.

Can not deserialize instance of java.util.ArrayList out of START_OBJECT token

Related to Eugen's answer, you can solve this particular case by creating a wrapper POJO object that contains a Collection<COrder> as its member variable. This will properly guide Jackson to place the actual Collection data inside the POJO's member variable and produce the JSON you are looking for in the API request.


public class ApiRequest {

   private Collection<COrder> collection;

   // getters

Then set the parameter type of COrderRestService.postOrder() to be your new ApiRequest wrapper POJO instead of Collection<COrder>.

How do I return clean JSON from a WCF Service?

Change the return type of your GetResults to be List<Person>.
Eliminate the code that you use to serialize the List to a json string - WCF does this for you automatically.

Using your definition for the Person class, this code works for me:

public List<Person> GetPlayers()
    List<Person> players = new List<Person>();
    players.Add(new  Person { FirstName="Peyton", LastName="Manning", Age=35 } );
    players.Add(new  Person { FirstName="Drew", LastName="Brees", Age=31 } );
    players.Add(new  Person { FirstName="Brett", LastName="Favre", Age=58 } );

    return players;



(All on one line)

I also used this attribute on the method:

[WebInvoke(Method = "GET",
           RequestFormat = WebMessageFormat.Json,
           ResponseFormat = WebMessageFormat.Json,
           UriTemplate = "players")]

WebInvoke with Method= "GET" is the same as WebGet, but since some of my methods are POST, I use all WebInvoke for consistency.

The UriTemplate sets the URL at which the method is available. So I can do a GET on http://myserver/myvdir/JsonService.svc/players and it just works.

Also check out IIRF or another URL rewriter to get rid of the .svc in the URI.

Is there a way to 'pretty' print MongoDB shell output to a file?

I managed to save result with writeFile() function.

> writeFile("/home/pahan/output.txt", tojson(db.myCollection.find().toArray()))

Mongo shell version was 4.0.9

How to fetch Java version using single line command in Linux

Since (at least on my linux system) the version string looks like "1.8.0_45":

 function checkJavaVers {
    for token in $(java -version 2>&1)
        if [[ $token =~ \"([[:digit:]])\.([[:digit:]])\.(.*)\" ]]
            export JAVA_MAJOR=${BASH_REMATCH[1]}
            export JAVA_MINOR=${BASH_REMATCH[2]}
            export JAVA_BUILD=${BASH_REMATCH[3]}
            return 0
    return 1

checkJavaVers || { echo "check failed" ; exit; }

Redeploy alternatives to JRebel

Take a look at DCEVM, it's a modification of the HotSpot VM that allows unlimited class redefinitions at runtime. You can add/remove fields and methods and change the super types of a class at runtime.

The binaries available on the original site are limited to Java 6u25 and to early versions of Java 7. The project has been forked on Github and supports recent versions of Java 7 and 8. The maintainer provides binaries for 32/64 bits VMs on Windows/Linux. Starting with Java 11 the project moved to a new GitHub repository and now also provides binaries for OS X.

DCEVM is packaged for Debian and Ubuntu, it's conveniently integrated with OpenJDK and can be invoked with java -dcevm. The name of the package depends on the version of the default JDK:

HTML list-style-type dash

In my case adding this code to CSS

ul {
    list-style-type: '- ';

was enough. Simple as it is.

Developing for Android in Eclipse: not regenerating

Here's what worked for me that the other answers didn't:

  1. Create new Android Application Project,
  2. Copy all files and folders from old directory (except /gen) and replace!
  3. Refresh project root in Package Explorer.
  4. If still there, Clean again!

    Done. Hope this helps.

jquery <a> tag click event

That's because your hidden fields have duplicate IDs, so jQuery only returns the first in the set. Give them classes instead, like .uid and grab them via:

var uids = $(".uid").map(function() {
    return this.value;


EDIT: say your output looks like the following (notice, IDs have changed to classes)

<fieldset><legend>John Smith</legend>
<img src='foo.jpg'/><br>
<a href="#" class="aaf">add as friend</a>
<input name="uid" type="hidden" value='<?php echo $row->uid;?>' class="uid">

You can target the 'uid' relative to the clicked anchor like this:

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

Important: do not have any duplicate IDs. They will cause problems. They are invalid, bad and you should not do it.


if not exists (select * from sysobjects where name='cars' and xtype='U')
    create table cars (
        Name varchar(64) not null

The above will create a table called cars if the table does not already exist.

How do you create a Spring MVC project in Eclipse?

This is the easiest way :

step 1) install Spring Tool Suite (STS) for eclipse (version 3.7.0RELEASE or above) To do this you can go to Help >> eclipse market place , then type Spring Tool suite in search box.

step 2) now go to file >> new >> spring project as shown in the image below enter image description here

step 3)now choose the template as "spring MVC Project" and give a name to your project on the top as shown below ( I named it 'SpringProject') enter image description here

step 4)now give a base package name like this enter image description here

and that is . The project will be created in a few minutes and Now you can right click on it and run on server.

Apache VirtualHost 403 Forbidden

If you did everything right, just give the permission home directory like:

sudo chmod o+x $HOME


sudo systemctl restart apache2

How to make a custom LinkedIn share button

Official LinkedIn API for sharing:

Read Terms of Use!

Example link using "Customized URL" method:

You just need to open it in popup using JavaScript or load it to iframe. Simple and works - that's what I was looking for!

EDIT: Video attached to a post:

I checked that you can't really embed any video to LinkedIn post, the only option is to add the link to the page with video itself.

You can achieve it by putting YT link into url param:

If you specify summary and title then LinkedIn will stop pulling it from the video, e.g.:

It does work exactly the same with Vimeo, and probably will work for any website. Hope it will help.

EDIT 2: Pulling images to the post:

When you open above links you will see that LinkedIn loads some images along with the passed URL (and optionally title and summary).

LinkedIn does it automatically, and you can read about it here:

It's interesting though as it says:

If Open Graph tags are present, LinkedIn's crawler will not have to rely on it's own analysis to determine what content will be shared, which improves the likelihood that the information that is shared is exactly what you intended.

It tells me that even if Open Graph information is not attached, LinkedIn can pull this data based on its own analysis. And in case of YouTube it seems to be the case, as I couldn't find any Open Graph tags added to YouTube pages.

Generating all permutations of a given string

Here is algorithm with O(n!) time complexity with pure recursion and intuitive .

public class words {
static String combinations;
public static List<String> arrlist=new ArrayList<>();
public static void main(String[] args) {
    words obj = new words();

    String str="premandl";
    obj.getcombination(str, str.length()-1, "");


public void getcombination(String str, int charIndex, String output) {

    if (str.length() == 0) {
        return ;

    if (charIndex == -1) {
        return ;

    String character = str.toCharArray()[charIndex] + "";
    getcombination(str, --charIndex, output);

    String remaining = "";

    output = output + character;

    remaining = str.substring(0, charIndex + 1) + str.substring(charIndex + 2);

    getcombination(remaining, remaining.length() - 1, output);



Failed to instantiate module [$injector:unpr] Unknown provider: $routeProvider

adding to scotty's answer:

Option 1: Either include this in your JS file:

<script src=""></script>

Option 2: or just use the URL to download 'angular-route.min.js' to your local.

and then (whatever option you choose) add this 'ngRoute' as dependency.

explained: var app = angular.module('myapp', ['ngRoute']);


Shall we always use [unowned self] inside closure in Swift

There are some great answers here. But recent changes to how Swift implements weak references should change everyone's weak self vs. unowned self usage decisions. Previously, if you needed the best performance using unowned self was superior to weak self, as long as you could be certain that self would never be nil, because accessing unowned self is much faster than accessing weak self.

But Mike Ash has documented how Swift has updated the implementation of weak vars to use side-tables and how this substantially improves weak self performance.

Now that there isn't a significant performance penalty to weak self, I believe we should default to using it going forward. The benefit of weak self is that it's an optional, which makes it far easier to write more correct code, it's basically the reason Swift is such a great language. You may think you know which situations are safe for the use of unowned self, but my experience reviewing lots of other developers code is, most don't. I've fixed lots of crashes where unowned self was deallocated, usually in situations where a background thread completes after a controller is deallocated.

Bugs and crashes are the most time-consuming, painful and expensive parts of programming. Do your best to write correct code and avoid them. I recommend making it a rule to never force unwrap optionals and never use unowned self instead of weak self. You won't lose anything missing the times force unwrapping and unowned self actually are safe. But you'll gain a lot from eliminating hard to find and debug crashes and bugs.

Split a string into array in Perl

You already have multiple answers to your question, but I would like to add another minor one here that might help to add something.

To view data structures in Perl you can use Data::Dumper. To print a string you can use say, which adds a newline character "\n" after every call instead of adding it explicitly.

I usually use \s which matches a whitespace character. If you add + it matches one or more whitespace characters. You can read more about it here perlre.


use strict;
use warnings;

use Data::Dumper;

use feature 'say';

my $line = "file1.gz file2.gz file3.gz";
my @abc  = split /\s+/, $line;

print Dumper \@abc;
say for @abc;

How do you simulate Mouse Click in C#?

I have combined several sources to produce the code below, which I am currently using. I have also removed the Windows.Forms references so I can use it from console and WPF applications without additional references.

using System;
using System.Runtime.InteropServices;

public class MouseOperations
    public enum MouseEventFlags
        LeftDown = 0x00000002,
        LeftUp = 0x00000004,
        MiddleDown = 0x00000020,
        MiddleUp = 0x00000040,
        Move = 0x00000001,
        Absolute = 0x00008000,
        RightDown = 0x00000008,
        RightUp = 0x00000010

    [DllImport("user32.dll", EntryPoint = "SetCursorPos")]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool SetCursorPos(int x, int y);      

    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool GetCursorPos(out MousePoint lpMousePoint);

    private static extern void mouse_event(int dwFlags, int dx, int dy, int dwData, int dwExtraInfo);

    public static void SetCursorPosition(int x, int y) 
        SetCursorPos(x, y);

    public static void SetCursorPosition(MousePoint point)
        SetCursorPos(point.X, point.Y);

    public static MousePoint GetCursorPosition()
        MousePoint currentMousePoint;
        var gotPoint = GetCursorPos(out currentMousePoint);
        if (!gotPoint) { currentMousePoint = new MousePoint(0, 0); }
        return currentMousePoint;

    public static void MouseEvent(MouseEventFlags value)
        MousePoint position = GetCursorPosition();


    public struct MousePoint
        public int X;
        public int Y;

        public MousePoint(int x, int y)
            X = x;
            Y = y;

How to check if one of the following items is in a list?

a = {2,3,4}
if {1,2} & a:

Code golf version. Consider using a set if it makes sense to do so. I find this more readable than a list comprehension.

How to check if a specific key is present in a hash or not?

Hash's key? method tells you whether a given key is present or not.


How to force keyboard with numbers in mobile website in Android

This should work. But I have same problems on an Android phone.

<input type="number" /> <input type="tel" />

I found out, that if I didn't include the jquerymobile-framework, the keypad showed correctly on the two types of fields.

But I havn't found a solution to solve that problem, if you really need to use jquerymobile.

UPDATE: I found out, that if the form-tag is stored out of the

<div data-role="page"> 

The number keypad isn't shown. This must be a bug...

How can I get the content of CKEditor using JQuery?

version 4.8.0


Correct use of transactions in SQL Server

Add a try/catch block, if the transaction succeeds it will commit the changes, if the transaction fails the transaction is rolled back:



      INSERT INTO [Test].[dbo].[T1] ([Title], [AVG])
      VALUES ('Tidd130', 130), ('Tidd230', 230)

      UPDATE [Test].[dbo].[T1]
      SET [Title] = N'az2' ,[AVG] = 1
      WHERE [dbo].[T1].[Title] = N'az'






HTML Form Redirect After Submit

Try this Javascript (jquery) code. Its an ajax request to an external URL. Use the callback function to fire any code:

<script type="text/javascript">
$(function() {
    $.post('', function() {
      window.location = '';
    return false;

How can I make my layout scroll both horizontally and vertically?

its too late but i hope your issue will be solve quickly with this code. nothing to do more just put your code in below scrollview.


            //xml code

Use PHP composer to clone git repo

You can include git repository to composer.json like this:

"repositories": [
    "type": "package",
    "package": {
        "name": "example-package-name", //give package name to anything, must be unique
        "version": "1.0",
        "source": {
            "url": "", //git url
            "type": "git",
            "reference": "master" //git branch-name
"require" : {
  "example-package-name": "1.0"

How do I "break" out of an if statement?

if (test)
    goto jmp;

Oh why not :)

Get latitude and longitude based on location name with Google Autocomplete API

The below is the code that i used. It's working perfectly.

var geo = new google.maps.Geocoder;
geo.geocode({'address':address},function(results, status){
    if (status == google.maps.GeocoderStatus.OK) {              
        var myLatLng = results[0].geometry.location;

        // Add some code to work with myLatLng              

    } else {
        alert("Geocode was not successful for the following reason: " + status);

Hope this will help.

phpmyadmin "Not Found" after install on Apache, Ubuntu

Run the following command in terminal:

sudo ln -s /usr/share/phpmyadmin /var/www/html/

How do you install an APK file in the Android emulator?

Download apk file from browser and then just click on it (notification area). Installation will start automatically.

MySQL Error 1093 - Can't specify target table for update in FROM clause

If something does not work, when coming thru the front-door, then take the back-door:

drop table if exists apples;
create table if not exists apples(variety char(10) primary key, price int);

insert into apples values('fuji', 5), ('gala', 6);

drop table if exists apples_new;
create table if not exists apples_new like apples;
insert into apples_new select * from apples;

update apples_new
    set price = (select price from apples where variety = 'gala')
    where variety = 'fuji';
rename table apples to apples_orig;
rename table apples_new to apples;
drop table apples_orig;

It's fast. The bigger the data, the better.

What is the use of adding a null key or value to a HashMap in Java?

Here's my only-somewhat-contrived example of a case where the null key can be useful:

public class Timer {
    private static final Logger LOG = Logger.getLogger(Timer.class);
    private static final Map<String, Long> START_TIMES = new HashMap<String, Long>();

    public static synchronized void start() {
        long now = System.currentTimeMillis();
        if (START_TIMES.containsKey(null)) {
            LOG.warn("Anonymous timer was started twice without being stopped; previous timer has run for " + (now - START_TIMES.get(null).longValue()) +"ms"); 
        START_TIMES.put(null, now);

    public static synchronized long stop() {
        if (! START_TIMES.containsKey(null)) {
            return 0;

        return printTimer("Anonymous", START_TIMES.remove(null), System.currentTimeMillis());

    public static synchronized void start(String name) {
        long now = System.currentTimeMillis();
        if (START_TIMES.containsKey(name)) {
            LOG.warn(name + " timer was started twice without being stopped; previous timer has run for " + (now - START_TIMES.get(name).longValue()) +"ms"); 
        START_TIMES.put(name, now);

    public static synchronized long stop(String name) {
        if (! START_TIMES.containsKey(name)) {
            return 0;

        return printTimer(name, START_TIMES.remove(name), System.currentTimeMillis());

    private static long printTimer(String name, long start, long end) { + " timer ran for " + (end - start) + "ms");
        return end - start;

How to change font of UIButton with Swift

This works in Swift 3.0:

btn.titleLabel?.font = UIFont(name:"Times New Roman", size: 20) 

Singleton with Arguments in Java

Singletons are generally considered to be anti-patterns and shouldn't be used. They do not make code easy to test.

A singleton with an argument makes no sense anyway - what would happen if you wrote:

Singleton s = SingletonHolder.getInstance(1);
Singleton t = SingletonHolder.getInstance(2); //should probably throw IllegalStateException

Your singleton is also not thread-safe as multiple threads can make simultaneous calls to getInstance resulting in more than one instance being created (possibly with different values of x).

How do check if a PHP session is empty?

If you want to check whether sessions are available, you probably want to use the session_id() function:

session_id() returns the session id for the current session or the empty string ("") if there is no current session (no current session id exists).

Database Structure for Tree Data Structure

Have a look at Managing Hierarchical Data in MySQL. It discusses two approaches for storing and managing hierarchical (tree-like) data in a relational database.

The first approach is the adjacency list model, which is what you essentially describe: having a foreign key that refers to the table itself. While this approach is simple, it can be very inefficient for certain queries, like building the whole tree.

The second approach discussed in the article is the nested set model. This approach is far more efficient and flexible. Refer to the article for detailed explanation and example queries.

What does "zend_mm_heap corrupted" mean

As per the bug tracker, set opcache.fast_shutdown=0. Fast shutdown uses the Zend memory manager to clean up its mess, this disables that.

Split a String into an array in Swift?

I found an Interesting case, that

method 1

var data:[String] = split( featureData ) { $0 == "\u{003B}" }

When I used this command to split some symbol from the data that loaded from server, it can split while test in simulator and sync with test device, but it won't split in publish app, and Ad Hoc

It take me a lot of time to track this error, It might cursed from some Swift Version, or some iOS Version or neither

It's not about the HTML code also, since I try to stringByRemovingPercentEncoding and it's still not work

addition 10/10/2015

in Swift 2.0 this method has been changed to

var data:[String] = featureData.split {$0 == "\u{003B}"}

method 2

var data:[String] = featureData.componentsSeparatedByString("\u{003B}")

When I used this command, it can split the same data that load from server correctly

Conclusion, I really suggest to use the method 2


Python 'list indices must be integers, not tuple"

The problem is that [...] in python has two distinct meanings

  1. expr [ index ] means accessing an element of a list
  2. [ expr1, expr2, expr3 ] means building a list of three elements from three expressions

In your code you forgot the comma between the expressions for the items in the outer list:

[ [a, b, c] [d, e, f] [g, h, i] ]

therefore Python interpreted the start of second element as an index to be applied to the first and this is what the error message is saying.

The correct syntax for what you're looking for is

[ [a, b, c], [d, e, f], [g, h, i] ]

Open new popup window without address bars in firefox & IE

Workaround - Open a modal popup window and embed the external URL as an iframe.

How to ping an IP address

I prefer to this way:

     * @param host
     * @return true means ping success,false means ping fail.
     * @throws IOException
     * @throws InterruptedException
    private static boolean ping(String host) throws IOException, InterruptedException {
        boolean isWindows = System.getProperty("").toLowerCase().contains("win");

        ProcessBuilder processBuilder = new ProcessBuilder("ping", isWindows? "-n" : "-c", "1", host);
        Process proc = processBuilder.start();
        return proc.waitFor(200, TimeUnit.MILLISECONDS);

This way can limit the blocking time to the specific time,such as 200 ms.

It works well in MacOS?Android and Windows, but should used in JDK 1.8.

This idea comes from Mohammad Banisaeid,but I can't comment. (You must have 50 reputation to comment)

html5 <input type="file" accept="image/*" capture="camera"> display as image rather than "choose file" button

For those who need the input file to open directly the camera, you just have to declare capture parameter to the input file, like this :

<input type="file" accept="image/*" capture>

What is the difference between a hash join and a merge join (Oracle RDBMS )?

I just want to edit this for posterity that the tags for oracle weren't added when I answered this question. My response was more applicable to MS SQL.

Merge join is the best possible as it exploits the ordering, resulting in a single pass down the tables to do the join. IF you have two tables (or covering indexes) that have their ordering the same such as a primary key and an index of a table on that key then a merge join would result if you performed that action.

Hash join is the next best, as it's usually done when one table has a small number (relatively) of items, its effectively creating a temp table with hashes for each row which is then searched continuously to create the join.

Worst case is nested loop which is order (n * m) which means there is no ordering or size to exploit and the join is simply, for each row in table x, search table y for joins to do.

Make hibernate ignore class variables that are not mapped

For folks who find this posting through the search engines, another possible cause of this problem is from importing the wrong package version of @Transient. Make sure that you import javax.persistence.transient and not some other package.

String field value length in mongoDB

This query will give both field value and length:

    $project: {
        "name": 1,
        "length": { $strLenCP: "$name" }
    }} ])

How I can get and use the header file <graphics.h> in my C++ program?

graphics.h appears to something once bundled with Borland and/or Turbo C++, in the 90's.

It's unlikely that you will find any support for that file with modern compiler. For other graphics libraries check the list of "related" questions (questions related to this one). E.g., "A Simple, 2d cross-platform graphics library for c or c++?".

How to generate unique id in MySQL?

This generates random ids:

    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int

sys.stdin.readline() reads without prompt, returning 'nothing in between'

Try this ...

import sys
buffer = []
while True:
    userinput = sys.stdin.readline().rstrip('\n')
    if userinput == 'quit':

Blade if(isset) is not working Laravel

Use ?? instead or {{ $usersType ?? '' }}

CSS smooth bounce animation

In case you're already using the transform property for positioning your element (as I currently am), you can also animate the top margin:

.ball {
  animation: bounce 1s infinite alternate;
  -webkit-animation: bounce 1s infinite alternate;

@keyframes bounce {
  from {
    margin-top: 0;
  to {
    margin-top: -15px;

How do I install an R package from source?

You can install directly from the repository (note the type="source"):

install.packages("RJSONIO", repos = "", type="source")

Redirecting to a certain route based on condition

 .when('/main' , {templateUrl: 'partials/main.html',  controller: MainController})
 .when('/login', {templateUrl: 'partials/login.html', controller: LoginController}).
 .when('/login', {templateUrl: 'partials/index.html', controller: IndexController})
 .otherwise({redirectTo: '/index'});

How to retrieve data from a SQL Server database in C#?

we can use this type of snippet also we generally use this kind of code for testing and validating data for DB to API fields

class Db
    private readonly static string ConnectionString =
    public static List<string> GetValuesFromDB(string LocationCode)
        List<string> ValuesFromDB = new List<string>();
        string LocationqueryString = "select BELocationCode,CityLocation,CityLocationDescription,CountryCode,CountryDescription " +
            $"from [CustomerLocations] where LocationCode='{LocationCode}';";
        using (SqlConnection Locationconnection =
                                 new SqlConnection(ConnectionString))
            SqlCommand command = new SqlCommand(LocationqueryString, Locationconnection);
                SqlDataReader Locationreader = command.ExecuteReader();
                while (Locationreader.Read())
                    for (int i = 0; i <= Locationreader.FieldCount - 1; i++)
                return ValuesFromDB;
            catch (Exception ex)



hope this might helpful

Note: you guys need connection string (in our case "DbConnectionString")

Get age from Birthdate


You can calculate with Dates.

var birthdate = new Date("1990/1/1");
var cur = new Date();
var diff = cur-birthdate; // This is the difference in milliseconds
var age = Math.floor(diff/31557600000); // Divide by 1000*60*60*24*365.25

How do you make a div follow as you scroll?

Using styling from CSS, you can define how something is positioned. If you define the element as fixed, it will always remain in the same position on the screen at all times.


Powershell script does not run via Scheduled Tasks

Good morning,

I know this is an old thread but I just ran across it while looking for a similar problem - script was running successfully but not doing its work. I can't find the post that helped me but my issue was that I was running the script as the domain admin. When I followed the suggestion of the post and added the domain admin to the local administrator's group it worked. I hope this helps others with the same issue I had.


Angular exception: Can't bind to 'ngForIn' since it isn't a known native property

my solution was - just remove '*' character from the expression ^__^

<div ngFor="let talk in talks">

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

Old question, but here's another explanation of the problem. You'll get this error even if you have strongly typed views and aren't using ViewData to create your dropdown list. The reason for the error can becomes clear when you look at the MVC source:

// If we got a null selectList, try to use ViewData to get the list of items.
if (selectList == null)
    selectList = htmlHelper.GetSelectData(name);
    usedViewData = true;

So if you have something like:

@Html.DropDownList("MyList", Model.DropDownData, "")

And Model.DropDownData is null, MVC looks through your ViewData for something named MyList and throws an error if there's no object in ViewData with that name.

Django values_list vs values

The best place to understand the difference is at the official documentation on values / values_list. It has many useful examples and explains it very clearly. The django docs are very user freindly.

Here's a short snippet to keep SO reviewers happy:


Returns a QuerySet that returns dictionaries, rather than model instances, when used as an iterable.

And read the section which follows it:


This is similar to values() except that instead of returning dictionaries, it returns tuples when iterated over.

Relation between CommonJS, AMD and RequireJS?

RequireJS implements the AMD API (source).

CommonJS is a way of defining modules with the help of an exports object, that defines the module contents. Simply put, a CommonJS implementation might work like this:

// someModule.js
exports.doSomething = function() { return "foo"; };

var someModule = require('someModule'); // in the vein of node    
exports.doSomethingElse = function() { return someModule.doSomething() + "bar"; };

Basically, CommonJS specifies that you need to have a require() function to fetch dependencies, an exports variable to export module contents and a module identifier (which describes the location of the module in question in relation to this module) that is used to require the dependencies (source). CommonJS has various implementations, including Node.js, which you mentioned.

CommonJS was not particularly designed with browsers in mind, so it doesn't fit in the browser environment very well (I really have no source for this--it just says so everywhere, including the RequireJS site.) Apparently, this has something to do with asynchronous loading, etc.

On the other hand, RequireJS implements AMD, which is designed to suit the browser environment (source). Apparently, AMD started as a spinoff of the CommonJS Transport format and evolved into its own module definition API. Hence the similarities between the two. The new feature in AMD is the define() function that allows the module to declare its dependencies before being loaded. For example, the definition could be:

define('module/id/string', ['module', 'dependency', 'array'], 
function(module, factory function) {
  return ModuleContents;  

So, CommonJS and AMD are JavaScript module definition APIs that have different implementations, but both come from the same origins.

  • AMD is more suited for the browser, because it supports asynchronous loading of module dependencies.
  • RequireJS is an implementation of AMD, while at the same time trying to keep the spirit of CommonJS (mainly in the module identifiers).

To confuse you even more, RequireJS, while being an AMD implementation, offers a CommonJS wrapper so CommonJS modules can almost directly be imported for use with RequireJS.

define(function(require, exports, module) {
  var someModule = require('someModule'); // in the vein of node    
  exports.doSomethingElse = function() { return someModule.doSomething() + "bar"; };

I hope this helps to clarify things!

how to achieve transfer file between client and server using java socket

Reading quickly through the source it seems that you're not far off. The following link should help (I did something similar but for FTP). For a file send from server to client, you start off with a file instance and an array of bytes. You then read the File into the byte array and write the byte array to the OutputStream which corresponds with the InputStream on the client's side.

Edit: Here's a working ultra-minimalistic file sender and receiver. Make sure you understand what the code is doing on both sides.

package filesendtest;


class TCPServer {

    private final static String fileToSend = "C:\\test1.pdf";

    public static void main(String args[]) {

        while (true) {
            ServerSocket welcomeSocket = null;
            Socket connectionSocket = null;
            BufferedOutputStream outToClient = null;

            try {
                welcomeSocket = new ServerSocket(3248);
                connectionSocket = welcomeSocket.accept();
                outToClient = new BufferedOutputStream(connectionSocket.getOutputStream());
            } catch (IOException ex) {
                // Do exception handling

            if (outToClient != null) {
                File myFile = new File( fileToSend );
                byte[] mybytearray = new byte[(int) myFile.length()];

                FileInputStream fis = null;

                try {
                    fis = new FileInputStream(myFile);
                } catch (FileNotFoundException ex) {
                    // Do exception handling
                BufferedInputStream bis = new BufferedInputStream(fis);

                try {
          , 0, mybytearray.length);
                    outToClient.write(mybytearray, 0, mybytearray.length);

                    // File sent, exit the main method
                } catch (IOException ex) {
                    // Do exception handling

package filesendtest;


class TCPClient {

    private final static String serverIP = "";
    private final static int serverPort = 3248;
    private final static String fileOutput = "C:\\testout.pdf";

    public static void main(String args[]) {
        byte[] aByte = new byte[1];
        int bytesRead;

        Socket clientSocket = null;
        InputStream is = null;

        try {
            clientSocket = new Socket( serverIP , serverPort );
            is = clientSocket.getInputStream();
        } catch (IOException ex) {
            // Do exception handling

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        if (is != null) {

            FileOutputStream fos = null;
            BufferedOutputStream bos = null;
            try {
                fos = new FileOutputStream( fileOutput );
                bos = new BufferedOutputStream(fos);
                bytesRead =, 0, aByte.length);

                do {
                        bytesRead =;
                } while (bytesRead != -1);

            } catch (IOException ex) {
                // Do exception handling


Byte array of unknown length in java

Edit: The following could be used to fingerprint small files before and after transfer (use SHA if you feel it's necessary):

public static String md5String(File file) {
    try {
        InputStream fin = new FileInputStream(file); md5er = MessageDigest.getInstance("MD5");
        byte[] buffer = new byte[1024];
        int read;
        do {
            read =;
            if (read > 0) {
                md5er.update(buffer, 0, read);
        } while (read != -1);
        byte[] digest = md5er.digest();
        if (digest == null) {
            return null;
        String strDigest = "0x";
        for (int i = 0; i < digest.length; i++) {
            strDigest += Integer.toString((digest[i] & 0xff)
                    + 0x100, 16).substring(1).toUpperCase();
        return strDigest;
    } catch (Exception e) {
        return null;

Getting value of select (dropdown) before change

This is an improvement on @thisisboris answer. It adds a current value to data, so the code can control when a variable set to the current value is changed.

    // Initialize the previous-attribute
    var selects = $( 'select' );
    $.each( selects, function( index, myValue ) {
        $( myValue ).data( 'mgc-previous', myValue.value );
        $( myValue ).data( 'mgc-current', myValue.value );  

    // Listen on the body for changes to selects
    $('body').on('change', 'select',
            alert('I am a body alert');
            $(this).data('mgc-previous', $(this).data( 'mgc-current' ) );
            $(this).data('mgc-current', $(this).val() );

How add unique key to existing table (with non uniques rows)

The proper syntax would be - ALTER TABLE Table_Name ADD UNIQUE (column_name)


ALTER TABLE  0_value_addition_setup ADD UNIQUE (`value_code`)

How can I check if a value is a json object?

You should return json always, but change its status, or in following example the ResponseCode property:

    /* Some error, you can add a message too */
} else {
    /* All fine, proceed with code */

Do you know the Maven profile for

You can put this configuration in your settings.xml file:


PHP MySQL Google Chart JSON - Complete Example

You can do this more easy way. And 100% works that you want

    $servername = "localhost";
    $username = "root";
    $password = "";  //your database password
    $dbname = "demo";  //your database name

    $con = new mysqli($servername, $username, $password, $dbname);

    if ($con->connect_error) {
        die("Connection failed: " . $con->connect_error);
        //echo ("Connect Successfully");
    $query = "SELECT Date_time, Tempout FROM alarm_value"; // select column
    $aresult = $con->query($query);


<!DOCTYPE html>
    <title>Massive Electronics</title>
    <script type="text/javascript" src="loder.js"></script>
    <script type="text/javascript">
        google.charts.load('current', {'packages':['corechart']});

        function drawChart(){
            var data = new google.visualization.DataTable();
            var data = google.visualization.arrayToDataTable([
                    while($row = mysqli_fetch_assoc($aresult)){
                        echo "['".$row["Date_time"]."', ".$row["Tempout"]."],";

            var options = {
                title: 'Date_time Vs Room Out Temp',
                curveType: 'function',
                legend: { position: 'bottom' }

            var chart = new google.visualization.AreaChart(document.getElementById('areachart'));
            chart.draw(data, options);

     <div id="areachart" style="width: 900px; height: 400px"></div>

loder.js link here loder.js

Good examples using java.util.logging

I'd use minlog, personally. It's extremely simple, as the logging class is a few hundred lines of code.

Create an ArrayList with multiple object types?


   ArrayList<Object> list = new ArrayList <>();`     


 ArrayList arraylist = new ArrayList();

how to change color of TextinputLayout's label and edittext underline android

Based on Fedor Kazakov and others answers, I created a default config.



    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>

    <style name="Widget.Design.TextInputLayout" parent="AppTheme">
        <item name="hintTextAppearance">@style/AppTheme.TextFloatLabelAppearance</item>
        <item name="errorTextAppearance">@style/AppTheme.TextErrorAppearance</item>
        <item name="counterTextAppearance">@style/TextAppearance.Design.Counter</item>
        <item name="counterOverflowTextAppearance">@style/TextAppearance.Design.Counter.Overflow</item>

    <style name="AppTheme.TextFloatLabelAppearance" parent="TextAppearance.Design.Hint">
        <!-- Floating label appearance here -->
        <item name="android:textColor">@color/colorAccent</item>
        <item name="android:textSize">20sp</item>

    <style name="AppTheme.TextErrorAppearance" parent="TextAppearance.Design.Error">
        <!-- Error message appearance here -->
        <item name="android:textColor">#ff0000</item>
        <item name="android:textSize">20sp</item>




        android:hint="Text hint here"
        android:text="5,2" />




Without focus:

Without focus

Error message:

enter image description here

here-document gives 'unexpected end of file' error

Here is a flexible way to do deal with multiple indented lines without using heredoc.

  echo 'Hello!'
  sed -e 's:^\s*::' < <(echo '
    Some indented text here.
    Some indented text here.
  if [[ true ]]; then
    sed -e 's:^\s\{4,4\}::' < <(echo '
      Some indented text here.
        Some extra indented text here.
      Some indented text here.

Some notes on this solution:

  • if the content is expected to have simple quotes, either escape them using \ or replace the string delimiters with double quotes. In the latter case, be careful that construction like $(command) will be interpreted. If the string contains both simple and double quotes, you'll have to escape at least of kind.
  • the given example print a trailing empty line, there are numerous way to get rid of it, not included here to keep the proposal to a minimum clutter
  • the flexibility comes from the ease with which you can control how much leading space should stay or go, provided that you know some sed REGEXP of course.

open_basedir restriction in effect. File(/) is not within the allowed path(s):

If you're running this with php file.php. You need to edit php.ini Find this file:

: locate php.ini

And append file's path to open_basedir property:

open_basedir = /srv/http/:/home/:/tmp/:/usr/share/pear/:/usr/share/webapps/:/etc/webapps/:/run/media/andrew/ext4/protected

How do I execute a *.dll file

While many people have pointed out that you can't execute dlls directly and should use rundll32.exe to execute exported functions instead, here is a screenshot of an actual dll file running just like an executable:

enter image description here

While you cannot run dll files directly, I suspect it is possible to run them from another process using a WinAPI function CreateProcess:

send bold & italic text on telegram bot with html

According to the docs you can set the parse_mode field to:

  • MarkdownV2
  • HTML

Markdown still works but it's now considered a legacy mode.

You can pass the parse_mode parameter like this:[yourBotKey]/sendMessage?chat_id=[yourChatId]&parse_mode=MarkdownV2&text=[yourMessage]

For bold and italic using MarkdownV2:

*bold text*
_italic text_

And for HTML:

<b>bold</b> or <strong>bold</strong>
<i>italic</I> or <em>italic</em>

Make sure to encode your query-string parameters regardless the format you pick. For example:

val message = "*bold text*";
val encodedMsg = URLEncoder.encode(message, "UTF-8");
  • Javascript (ref)
var message = "*bold text*"
var encodedMsg = encodeURIComponent(message)
$message = "*bold text*";
$encodedMsg = urlencode($message);

How to convert unsigned long to string

The standard approach is to use sprintf(buffer, "%lu", value); to write a string rep of value to buffer. However, overflow is a potential problem, as sprintf will happily (and unknowingly) write over the end of your buffer.

This is actually a big weakness of sprintf, partially fixed in C++ by using streams rather than buffers. The usual "answer" is to allocate a very generous buffer unlikely to overflow, let sprintf output to that, and then use strlen to determine the actual string length produced, calloc a buffer of (that size + 1) and copy the string to that.

This site discusses this and related problems at some length.

Some libraries offer snprintf as an alternative which lets you specify a maximum buffer size.

Java Initialize an int array in a constructor

private int[] data = new int[3];

This already initializes your array elements to 0. You don't need to repeat that again in the constructor.

In your constructor it should be:

data = new int[]{0, 0, 0};

Want to download a Git repository, what do I need (windows machine)?

Install mysysgit. (Same as Greg Hewgill's answer.)

Install Tortoisegit. (Tortoisegit requires mysysgit or something similiar like Cygwin.)

After TortoiseGit is installed, right-click on a folder, select Git Clone..., then enter the Url of the repository, then click Ok.

This answer is not any better than just installing mysysgit, but you can avoid the dreaded command line. :)

Make div (height) occupy parent remaining height

You can use floats for pushing content down:

You have a fixed size container:

#container {
    width: 300px; height: 300px;

Content is allowed to flow next to a float. Unless we set the float to full width:

#up {
    float: left;
    width: 100%;

While #up and #down share the top position, #down's content can only start after the bottom of the floated #up:

#down {

Convert row to column header for Pandas DataFrame,

It would be easier to recreate the data frame. This would also interpret the columns types from scratch.

headers = df.iloc[0]
new_df  = pd.DataFrame(df.values[1:], columns=headers)

Eclipse error "ADB server didn't ACK, failed to start daemon"

Killing Eclipse and then rebooting did not help me. I added the Android tool to the PATH variables, started Task Manager and killed adb.exe.

I restarted Eclipse, and then it worked.

Python: Making a beep noise

On linux: print('\007') will make the system bell sound.

Python/BeautifulSoup - how to remove all tags from an element?

You can use the decompose method in bs4:

soup = bs4.BeautifulSoup('<body><a href="">I linked to <i></i></a></body>')

for a in soup.find('a').children:
    if isinstance(a,bs4.element.Tag):

print soup

Out: <html><body><a href="">I linked to </a></body></html>

How do I validate a date in rails?

You can validate the date and time like so (in a method somewhere in your controller with access to your params if you are using custom selects) ...

# Set parameters
year = params[:date][:year].to_i
month = params[:date][:month].to_i
mday = params[:date][:mday].to_i
hour = params[:date][:hour].to_i
minute = params[:date][:minute].to_i

# Validate date, time and hour
valid_date    = Date.valid_date? year, month, mday
valid_hour    = (0..23).to_a.include? hour
valid_minute  = (0..59).to_a.include? minute
valid_time    = valid_hour && valid_minute

# Check if parameters are valid and generate appropriate date
if valid_date && valid_time
  second = 0
  offset = '0'
  DateTime.civil(year, month, mday, hour, minute, second, offset)
  # Some fallback if you want like ...

How to add a custom HTTP header to every WCF call?

var endpoint = new EndpointAddress(new Uri(RemoteAddress),
               new[] { AddressHeader.CreateAddressHeader(

Working Soap client example

The response of acdcjunior it was awesome, I just expand his explanation with the next code, where you can see how iterate over the XML elements.

public class SOAPClientSAAJ {

public static void main(String args[]) throws Exception {
    // Create SOAP Connection
    SOAPConnectionFactory soapConnectionFactory = SOAPConnectionFactory.newInstance();
    SOAPConnection soapConnection = soapConnectionFactory.createConnection();

    // Send SOAP Message to SOAP Server
    String url = "";
    SOAPMessage soapResponse =, url);

    SOAPPart soapPart=soapResponse.getSOAPPart();
    // SOAP Envelope
    SOAPEnvelope envelope=soapPart.getEnvelope();
    SOAPBody soapBody = envelope.getBody();

    Iterator<Node> itr=soapBody.getChildElements();
    while (itr.hasNext()) {

        Node node=(Node);
        if (node.getNodeType()==Node.ELEMENT_NODE) {
            System.out.println("reading Node.ELEMENT_NODE");
            Element ele=(Element)node;
            System.out.println("Body childs : "+ele.getLocalName());

            switch (ele.getNodeName()) {

          case "VerifyEmailResponse":
             NodeList statusNodeList = ele.getChildNodes();

             for(int i=0;i<statusNodeList.getLength();i++){
               Element emailResult = (Element) statusNodeList.item(i);
               System.out.println("VerifyEmailResponse childs : "+emailResult.getLocalName());
                switch (emailResult.getNodeName()) {

                case "VerifyEmailResult":
                    NodeList emailResultList = emailResult.getChildNodes();

                    for(int j=0;j<emailResultList.getLength();j++){
                      Element emailResponse = (Element) emailResultList.item(j);
                      System.out.println("VerifyEmailResult childs : "+emailResponse.getLocalName());
                       switch (emailResponse.getNodeName()) {
                       case "ResponseText":
                        case "ResponseCode":
                        case "LastMailServer":
                        case "GoodEmail":



        } else if (node.getNodeType()==Node.TEXT_NODE) {
            System.out.println("reading Node.TEXT_NODE");
            //do nothing here most likely, as the response nearly never has mixed content type
            //this is just for your reference
    // print SOAP Response
    System.out.println("Response SOAP Message:");


private static SOAPMessage createSOAPRequest() throws Exception {
    MessageFactory messageFactory = MessageFactory.newInstance();
    SOAPMessage soapMessage = messageFactory.createMessage();
    SOAPPart soapPart = soapMessage.getSOAPPart();

    String serverURI = "";

    // SOAP Envelope
    SOAPEnvelope envelope = soapPart.getEnvelope();
    envelope.addNamespaceDeclaration("example", serverURI);

    Constructed SOAP Request Message:
    <SOAP-ENV:Envelope xmlns:SOAP-ENV="" xmlns:example="">
                <example:email>[email protected]</example:email>

    // SOAP Body
    SOAPBody soapBody = envelope.getBody();
    SOAPElement soapBodyElem = soapBody.addChildElement("VerifyEmail", "example");
    SOAPElement soapBodyElem1 = soapBodyElem.addChildElement("email", "example");
    soapBodyElem1.addTextNode("[email protected]");
    SOAPElement soapBodyElem2 = soapBodyElem.addChildElement("LicenseKey", "example");

    MimeHeaders headers = soapMessage.getMimeHeaders();
    headers.addHeader("SOAPAction", serverURI  + "VerifyEmail");


    /* Print the request message */
    System.out.println("Request SOAP Message:");

    return soapMessage;


make an html svg object also a clickable link

The easiest way is to not use <object>. Instead use an <img> tag and the anchor should work just fine.

Zoom in on a point (using scale and translate)

if(wheel > 0) {
    this.scale *= 1.1; 
    this.offsetX -= (mouseX - this.offsetX) * (1.1 - 1);
    this.offsetY -= (mouseY - this.offsetY) * (1.1 - 1);
else {
    this.scale *= 1/1.1; 
    this.offsetX -= (mouseX - this.offsetX) * (1/1.1 - 1);
    this.offsetY -= (mouseY - this.offsetY) * (1/1.1 - 1);

HTML5 event handling(onfocus and onfocusout) using angular 2

If you want to catch the focus event dynamiclly on every input on your component :

import { AfterViewInit, Component, ElementRef } from '@angular/core';

  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
export class AppComponent implements AfterViewInit {

  constructor(private el: ElementRef) {

  ngAfterViewInit() {
       // document.getElementsByTagName('input') : to gell all Docuement imputs
       const inputList = []<HTMLElement>this.el.nativeElement).getElementsByTagName('input'));
        inputList.forEach((input: HTMLElement) => {
            input.addEventListener('focus', () => {
                input.setAttribute('placeholder', 'focused');
            input.addEventListener('blur', () => {

Checkout the full code here :

no matching function for call to ' '

You are passing pointers (Complex*) when your function takes references (const Complex&). A reference and a pointer are entirely different things. When a function expects a reference argument, you need to pass it the object directly. The reference only means that the object is not copied.

To get an object to pass to your function, you would need to dereference your pointers:

Complex::distanta(*firstComplexNumber, *secondComplexNumber);

Or get your function to take pointer arguments.

However, I wouldn't really suggest either of the above solutions. Since you don't need dynamic allocation here (and you are leaking memory because you don't delete what you have newed), you're better off not using pointers in the first place:

Complex firstComplexNumber(81, 93);
Complex secondComplexNumber(31, 19);
Complex::distanta(firstComplexNumber, secondComplexNumber);