Programs & Examples On #Soapfault

The SOAP Fault element is defined as part of the W3C SOAP specification. The SOAP Fault element is used to carry error information within a SOAP message.

SOAP PHP fault parsing WSDL: failed to load external entity?

I had the same problem, I succeeded by adding:

new \SoapClient(URI WSDL OR NULL if non-WSDL mode, [
    'cache_wsdl' => WSDL_CACHE_NONE, 
    'proxy_host' => 'URL PROXY',
    'proxy_port' => 'PORT PROXY'

Hope this help :)

SoapFault exception: Could not connect to host

If the connection is through SSL, could be a problem of server instead of client (it is my case).

In PHP versions greater than 5.6 and 7, is important to check the CipherSuite used in server certificate. There is a full list of ciphers allowed by this versions and a full list of ciphers that do not in this web link:

If the cipher used is not allowed (it is a deprecated algorithm), SoapClient receives "Could not connect to host" and there is no more trace about it.

The cipher used can be checked by clients like SoapUI in the section of "SSL Info", for example.

There is no thread forum treating about this in internet.

Check this out, too:

Uncaught SoapFault exception: [HTTP] Error Fetching http headers

Please update your php.ini with

default_socket_timeout = 120

You can create your own php.ini if php is installed a CGI instead of a Apache module

HTML select drop-down with an input field

You can use input text with "list" attribute, which refers to the datalist of values.

<input type="text" name="city" list="cityname">_x000D_
    <datalist id="cityname">_x000D_
      <option value="Boston">_x000D_
      <option value="Cambridge">_x000D_

This creates a free text input field that also has a drop-down to select predefined choices. Attribution for example and more information:

Is there a mechanism to loop x times in ES6 (ECMAScript 6) without mutable variables?

I made this:

function repeat(func, times) {
    for (var i=0; i<times; i++) {


repeat(function(i) {
    console.log("Hello, World! - "+i);
}, 5)

Hello, World! - 0
Hello, World! - 1
Hello, World! - 2
Hello, World! - 3
Hello, World! - 4

The i variable returns the amount of times it has looped - useful if you need to preload an x amount of images.

Updating a java map entry

You just use the method

public Object put(Object key, Object value)

if the key was already present in the Map then the previous value is returned.

comparing elements of the same array in java

First things first, you need to loop to < a.length rather than a.length - 1. As this is strictly less than you need to include the upper bound.

So, to check all pairs of elements you can do:

for (int i = 0; i < a.length; i++) {
    for (int k = 0; k < a.length; k++) {
        if (a[i] != a[k]) {
            //do stuff

But this will compare, for example a[2] to a[3] and then a[3] to a[2]. Given that you are checking != this seems wasteful.

A better approach would be to compare each element i to the rest of the array:

for (int i = 0; i < a.length; i++) {
    for (int k = i + 1; k < a.length; k++) {
        if (a[i] != a[k]) {
            //do stuff

So if you have the indices [1...5] the comparison would go

  1. 1 -> 2
  2. 1 -> 3
  3. 1 -> 4
  4. 1 -> 5
  5. 2 -> 3
  6. 2 -> 4
  7. 2 -> 5
  8. 3 -> 4
  9. 3 -> 5
  10. 4 -> 5

So you see pairs aren't repeated. Think of a circle of people all needing to shake hands with each other.

How to copy and edit files in Android shell?

If you just want to append to a file, e.g. to add some lines to a configuration file, inbuilt shell commands are enough:

adb shell
cat >> /path/to/file <<EOF
some text to append
a second line of text to append

In the above, replace /path/to/file with the file you want to edit. You'll need to have write permission on the file, which implies root access if you're editing a system file. Secondly, replace some text to append and a second line of text to append with the lines you want to add.

jQuery get selected option value (not the text, but the attribute 'value')

 $(document ).ready(function() {
    $('select[name=selectorname]').change(function() { 

JQuery - $ is not defined

That error means that jQuery has not yet loaded on the page. Using $(document).ready(...) or any variant thereof will do no good, as $ is the jQuery function.

Using window.onload should work here. Note that only one function can be assigned to window.onload. To avoid losing the original onload logic, you can decorate the original function like so:

originalOnload = window.onload;
window.onload = function() {
  if (originalOnload) {

This will execute the function that was originally assigned to window.onload, and then will execute // YOUR JQUERY.

See for more detail about the decorator pattern.

Convert a char to upper case using regular expressions (EditPad Pro)

You can also capitalize the first letter of the match using \I1 and \I2 etc instead of $1 and $2.

Check if a string is a palindrome

String extension method, easy to use:

    public static bool IsPalindrome(this string str)
        str = new Regex("[^a-zA-Z]").Replace(str, "").ToLower();
        return !str.Where((t, i) => t != str[str.Length - i - 1]).Any();

self.tableView.reloadData() not working in Swift

Try it: tableView.reloadSections(IndexSet(integersIn: 0...0), with: .automatic) It helped me

How to easily get network path to the file you are working on?

Answer to my own question. The only way I have found that works consistently and instantaneously is to:

1) Create a link in my "Favorites" to the directory I use

2) Update the properties on that favorite to be an absolute path (\\ads\IT-DEPT-DFS\Data\MAILROOM)

3) When saving a new file, I navigate to that directory only via the Favorites directory created above (or you can use any Shortcut with an absolute path)

4) After saving, go to the File tab and the full path can be copied from the top of the Info (default) section

How to execute a function when page has fully loaded?

In modern browsers with modern javascript (>= 2015) you can add type="module" to your script tag, and everything inside that script will execute after whole page loads. e.g:

<script type="module">
  alert("runs after") // Whole page loads before this line execute
  alert("runs before")

also older browsers will understand nomodule attribute. Something like this:

<script nomodule>
  alert("tuns after")

For more information you can visit

Create Table from JSON Data with angularjs and ng-repeat

You can use $http.get() method to fetch your JSON file. Then assign response data to a $scope object. In HTML to create table use ng-repeat for $scope object. ng-repeat will loop the rows in-side this loop you can bind data to columns dynamically.

I have checked your code and you have created static table

<tr ng-repeat="indivisual in members">
<td>{{ indivisual.Name }}</td>
<td>{{ indivisual.Relation }}</td>

so better your can go to my code to create dynamic table as per data you column and row will be increase or decrease..

How does the getView() method work when creating your own custom adapter?

getView() method in Adapter is for generating item's view of a ListView, Gallery,...

  1. LayoutInflater is used to get the View object which you define in a layout xml (the root object, normally a LinearLayout, FrameLayout, or RelativeLayout)

  2. convertView is for recycling. Let's say you have a listview which can only display 10 items at a time, and currently it is displaying item 1 -> item 10. When you scroll down one item, the item 1 will be out of screen, and item 11 will be displayed. To generate View for item 11, the getView() method will be called, and convertView here is the view of item 1 (which is not neccessary anymore). So instead create a new View object for item 11 (which is costly), why not re-use convertView? => we just check convertView is null or not, if null create new view, else re-use convertView.

  3. parentView is the ListView or Gallery... which contains the item's view which getView() generates.

Note: you don't call this method directly, just need to implement it to tell the parent view how to generate the item's view.

How can I convert a string to upper- or lower-case with XSLT?

In XSLT 1.0 the upper-case() and lower-case() functions are not available. If you're using a 1.0 stylesheet the common method of case conversion is translate():

<xsl:variable name="lowercase" select="'abcdefghijklmnopqrstuvwxyz'" />
<xsl:variable name="uppercase" select="'ABCDEFGHIJKLMNOPQRSTUVWXYZ'" />

<xsl:template match="/">
  <xsl:value-of select="translate(doc, $lowercase, $uppercase)" />

Connecting to SQL Server with Visual Studio Express Editions

My guess is that with VWD your solutions are more likely to be deployed to third party servers, many of which do not allow for a dynamically attached SQL Server database file. Thus the allowing of the other connection type.

This difference in IDE behavior is one of the key reasons for upgrading to a full version.

This action could not be completed. Try Again (-22421)

As with all thing Xcode related. A simple reboot fixed the problem for me.

Issue in installing php7.2-mcrypt

@praneeth-nidarshan has covered mostly all the steps, except some:

  • Check if you have pear installed (or install):

$ sudo apt-get install php-pear

  • Install, if isn't already installed, php7.2-dev, in order to avoid the error:

sh: phpize: not found

ERROR: `phpize’ failed

$ sudo apt-get install php7.2-dev

  • Install mcrypt using pecl:

$ sudo pecl install mcrypt-1.0.1

  • Add the extention to your php.ini configuration file; if you don't know where it is, search with:

$ sudo php -i | grep 'Configuration File'

Setting the JVM via the command line on Windows

You should be able to do this via the command line arguments, assuming these are Sun VMs installed using the usual Windows InstallShield mechanisms with the JVM finder EXE in system32.

Type java -help for the options. In particular, see:

              require the specified version to run
-jre-restrict-search | -jre-no-restrict-search
              include/exclude user private JREs in the version search

Getting time span between two times in C#?

string startTime = "7:00 AM";
string endTime = "2:00 PM";

TimeSpan duration = DateTime.Parse(endTime).Subtract(DateTime.Parse(startTime));


Will output: 07:00:00.

It also works if the user input military time:

string startTime = "7:00";
string endTime = "14:00";

TimeSpan duration = DateTime.Parse(endTime).Subtract(DateTime.Parse(startTime));


Outputs: 07:00:00.

To change the format: duration.ToString(@"hh\:mm")

More info at:


Over the years it has somewhat bothered me that this is the most popular answer I have ever given; the original answer never actually explained why the OP's code didn't work despite the fact that it is perfectly valid. The only reason it gets so many votes is because the post comes up on Google when people search for a combination of the terms "C#", "timespan", and "between".

How do I mount a remote Linux folder in Windows through SSH?

Dokan looks like a FUSE and sshfs implementation for Windows. If it works as expected and advertised, it would do exactly what you are looking for.

(Link updated and working 2015-10-15)

How to hide columns in HTML table?

<!doctype html>
<html lang="en">
<style id="myStyleSheet">

var column = 3;
var styleSheet = document.getElementById("myStyleSheet").sheet;
var rule = "table  tr td:nth-child("+ column +"),table th:nth-child("+ column +") 
{display: none}";

What’s the best way to check if a file exists in C++? (cross platform)

How about access?

#include <io.h>

if (_access(filename, 0) == -1)
    // File does not exist

SQL Server Management Studio alternatives to browse/edit tables and run queries

TOAD for MS SQL looks pretty good. I've never used it personally but I have used Quest's other products and they're solid.

Maintain model of scope when changing between views in AngularJS

An alternative to services is to use the value store.

In the base of my app I added this

var agentApp = angular.module('rbAgent', ['ui.router', 'rbApp.tryGoal', 'rbApp.tryGoal.service', 'ui.bootstrap']);

        contextId: '',
        sessionId: ''

And then in my controller I just reference the value store. I don't think it holds thing if the user closes the browser.

.controller('AgentGoalListController', ['agentMemory', '$scope', '$rootScope', 'config', '$state', function(agentMemory, $scope, $rootScope, config, $state){

$scope.config = config;
$scope.contextId = agentMemory.contextId;

How to get a random number in Ruby

You can generate a random number with the rand method. The argument passed to the rand method should be an integer or a range, and returns a corresponding random number within the range:

rand(9)       # this generates a number between 0 to 8
rand(0 .. 9)  # this generates a number between 0 to 9
rand(1 .. 50) # this generates a number between 1 to 50
#rand(m .. n) # m is the start of the number range, n is the end of number range

How to make vim paste from (and copy to) system's clipboard?

If you are using vim in MAC OSX, unfortunately it comes with older verion, and not complied with clipboard options. Luckily, homebrew can easily solve this problem.

install vim:

brew install vim --with-lua --with-override-system-vim

install gui verion of vim:

brew install macvim --with-lua --with-override-system-vim

restart the terminal to take effect.

append the following line to ~/.vimrc
set clipboard=unnamed

now you can copy the line in vim with yy and paste it system-wide.

How to disable Django's CSRF validation?

In in MIDDLEWARE you can simply remove/comment this line:


PHP - count specific array values

$array = array("Kyle","Ben","Sue","Phil","Ben","Mary","Sue","Ben");
$counts = array_count_values($array);
echo $counts['Ben'];

Responsive Images with CSS

Use max-width on the images too. Change:

.erb-image-wrapper img{
    width:100% !important;
    height:100% !important;


.erb-image-wrapper img{
    max-width:100% !important;
    max-height:100% !important;

How to link to specific line number on github

a permalink to a code snippet is pasted into a pull request comment field

You can you use permalinks to include code snippets in issues, PRs, etc.


Using PI in python 2.7

To have access to stuff provided by math module, like pi. You need to import the module first:

import math
print (math.pi)

How to list all the roles existing in Oracle database?


SELECT SUBSTR(TRIM(rtp.role),1,12)          AS ROLE
     , SUBSTR(rp.grantee,1,16)              AS GRANTEE
     , SUBSTR(TRIM(rtp.privilege),1,12)     AS PRIVILEGE
     , SUBSTR(TRIM(rtp.owner),1,12)         AS OWNER
     , SUBSTR(TRIM(rtp.table_name),1,28)    AS TABLE_NAME
     , SUBSTR(TRIM(rtp.column_name),1,20)   AS COLUMN_NAME
     , SUBSTR(rtp.common,1,4)               AS COMMON
     , SUBSTR(rtp.grantable,1,4)            AS GRANTABLE
     , SUBSTR(rp.default_role,1,16)         AS DEFAULT_ROLE
     , SUBSTR(rp.admin_option,1,4)          AS ADMIN_OPTION
  FROM role_tab_privs rtp
  LEFT JOIN dba_role_privs rp
    ON (rtp.role = rp.granted_role)
 WHERE ('&1' IS NULL OR UPPER(rtp.role) LIKE UPPER('%&1%'))
   AND ('&2' IS NULL OR UPPER(rp.grantee) LIKE UPPER('%&2%'))
   AND ('&3' IS NULL OR UPPER(rtp.table_name) LIKE UPPER('%&3%'))
   AND ('&4' IS NULL OR UPPER(rtp.owner) LIKE UPPER('%&4%'))
        , 2
        , 3
        , 4


SQLPLUS> @all_roles '' '' '' '' '' ''
SQLPLUS> @all_roles 'somerol' '' '' '' '' ''
SQLPLUS> @all_roles 'roler' 'username' '' '' '' ''
SQLPLUS> @all_roles '' '' 'part-of-database-package-name' '' '' ''

UITableView Cell selected Color?

If you have a grouped table with just one cell per section, just add this extra line to the code: bgColorView.layer.cornerRadius = 10;

UIView *bgColorView = [[UIView alloc] init];
[bgColorView setBackgroundColor:[UIColor redColor]];
bgColorView.layer.cornerRadius = 10;
[cell setSelectedBackgroundView:bgColorView];
[bgColorView release]; 

Don't forget to import QuartzCore.

how to make log4j to write to the console as well

This works well for console in debug mode

log4j.appender.console.layout.conversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} %-5p - %m%n

How to launch jQuery Fancybox on page load?

You can put link like this (it will be hidden. May be before </body>)

<a id="clickbanner" href="image.jpg" rel="gallery"></a>

And working rel attribute or class like this

$(document).ready(function() {
        openEffect  : 'elastic',
        closeEffect : 'elastic',
        maxWidth    : 800,
        maxHeight   : 600

Just do it with jquery trigger function

$( window ).load(function() {

Changing Node.js listening port

you can get the nodejs configuration from
The important thing you need to keep in your mind is about its configuration in file app.js which consists of port number host and other settings these are settings working for me

backendSettings = {
"scheme":"https / http ",
"host":"Your website url",
"port":49165, //port number 
'sslKeyPath': 'Path for key',
'sslCertPath': 'path for SSL certificate',
'sslCAPath': '',
"baseAuthPath": '/nodejs/',
"scheme": 'https / http', //whatever is your website scheme
"host":"host name",
"addUserToChannelUrl": 'user/channel/add/:channel/:uid',
"publishMessageToContentChannelUrl": 'content/token/message',

In this if you are getting "Error: listen EADDRINUSE" then please change the port number i.e, here I am using "49165" so you can use other port such as 49170 or some other port. For this you can refer to the following article

IOError: [Errno 13] Permission denied

IOError: [Errno 13] Permission denied: 'juliodantas2015.json'

tells you everything you need to know: though you successfully made your python program executable with your chmod, python can't open that juliodantas2015.json' file for writing. You probably don't have the rights to create new files in the folder you're currently in.

Set color of text in a Textbox/Label to Red and make it bold in C#

string minusvalue = TextBox1.Text.ToString();

if (Convert.ToDouble(minusvalue) < 0)
    // set color of text in TextBox1 to red color and bold.
    TextBox1.ForeColor = Color.Red;

String parsing in Java with delimiter tab "\t" using split

String[] columnDetail = new String[11];
columnDetail = column.split("\t", -1); // unlimited
columnDetail = column.split("\t", 11); // if you are sure about limit.
 * The {@code limit} parameter controls the number of times the
 * pattern is applied and therefore affects the length of the resulting
 * array.  If the limit <i>n</i> is greater than zero then the pattern
 * will be applied at most <i>n</i>&nbsp;-&nbsp;1 times, the array's
 * length will be no greater than <i>n</i>, and the array's last entry
 * will contain all input beyond the last matched delimiter.  If <i>n</i>
 * is non-positive then the pattern will be applied as many times as
 * possible and the array can have any length.  If <i>n</i> is zero then
 * the pattern will be applied as many times as possible, the array can
 * have any length, and trailing empty strings will be discarded.

SQL to find the number of distinct values in a column

select Count(distinct columnName) as columnNameCount from tableName 

Best way to randomize an array with .NET

You're looking for a shuffling algorithm, right?

Okay, there are two ways to do this: the clever-but-people-always-seem-to-misunderstand-it-and-get-it-wrong-so-maybe-its-not-that-clever-after-all way, and the dumb-as-rocks-but-who-cares-because-it-works way.

Dumb way

  • Create a duplicate of your first array, but tag each string should with a random number.
  • Sort the duplicate array with respect to the random number.

This algorithm works well, but make sure that your random number generator is unlikely to tag two strings with the same number. Because of the so-called Birthday Paradox, this happens more often than you might expect. Its time complexity is O(n log n).

Clever way

I'll describe this as a recursive algorithm:

To shuffle an array of size n (indices in the range [0..n-1]):

if n = 0
  • do nothing
if n > 0
  • (recursive step) shuffle the first n-1 elements of the array
  • choose a random index, x, in the range [0..n-1]
  • swap the element at index n-1 with the element at index x

The iterative equivalent is to walk an iterator through the array, swapping with random elements as you go along, but notice that you cannot swap with an element after the one that the iterator points to. This is a very common mistake, and leads to a biased shuffle.

Time complexity is O(n).

mysqli or PDO - what are the pros and cons?

Another notable (good) difference about PDO is that it's PDO::quote() method automatically adds the enclosing quotes, whereas mysqli::real_escape_string() (and similars) don't:

PDO::quote() places quotes around the input string (if required) and escapes special characters within the input string, using a quoting style appropriate to the underlying driver.

PHP: How to use array_filter() to filter array keys?

If you are looking for a method to filter an array by a string occurring in keys, you can use:

    function($key) use ($mSearch){
        return stristr($key,$mSearch);

The result of print_r($mResult) is

Array ( [foo] => bar [foo2] => bar2 [fooToo] => bar3 )

An adaption of this answer that supports regular expressions

function array_preg_filter_keys($arr, $regexp) {
  $keys = array_keys($arr);
  $match = array_filter($keys, function($k) use($regexp) {
    return preg_match($regexp, $k) === 1;
  return array_intersect_key($arr, array_flip($match));

$mArray = array('foo'=>'yes', 'foo2'=>'yes', 'FooToo'=>'yes', 'baz'=>'nope');

print_r(array_preg_filter_keys($mArray, "/^foo/i"));


    [foo] => yes
    [foo2] => yes
    [FooToo] => yes

How can I check for an empty/undefined/null string in JavaScript?

If you need to make sure that the string is not just a bunch of empty spaces (I'm assuming this is for form validation) you need to do a replace on the spaces.

if(str.replace(/\s/g,"") == ""){

How to get single value from this multi-dimensional PHP array

Look at the keys and indentation in your print_r:

echo $myarray[0]['email'];

echo $myarray[0]['gender'];


Get scroll position using jquery

Older IE and Firefox browsers attach the scrollbar to the documentElement, or what would be the <html> tag in HTML.

All other browsers attach the scrollbar to document.body, or what would be the <body> tag in HTML.

The correct solution would be to check which one to use, depending on browser

var doc = document.documentElement.clientHeight ? document.documentElement : document.body;
var s   = $(doc).scrollTop();

jQuery does make this a little easier, when passing in either window or document jQuery's scrollTop does a similar check and figures it out, so either of these should work cross-browser

var s = $(document).scrollTop();


var s = $(window).scrollTop();

jQuery scrollTop() docs

Description: Get the current vertical position of the scroll bar for the first element in the set of matched elements or set the vertical position of the scroll bar for every matched element.

...nothing that works for my div, just the full page

If it's for a DIV, you'd have to target the element that has the scrollbar attached, to get the scrolled amount


If you need to get the elements distance from the top of the document, you can also do


How do I expire a PHP session after 30 minutes?

Well i understand the aboves answers are correct but they are on application level, why don't we simply use .htaccess file to set the expire time ?

<IfModule mod_php5.c>
    #Session timeout
    php_value session.cookie_lifetime 1800
    php_value session.gc_maxlifetime 1800

How to instantiate, initialize and populate an array in TypeScript?

If you really want to have named parameters plus have your objects be instances of your class, you can do the following:

class bar {
    constructor (options?: {length: number; height: number;}) {
        if (options) {
            this.length = options.length;
            this.height = options.height;
    length: number;
    height: number;

class foo {
    bars: bar[] = new Array();

var ham = new foo();
ham.bars = [
    new bar({length: 4, height: 2}),
    new bar({length: 1, height: 3})

Also here's the related item on typescript issue tracker.

Sending and receiving UDP packets?

The receiver must set port of receiver to match port set in sender DatagramPacket. For debugging try listening on port > 1024 (e.g. 8000 or 9000). Ports < 1024 are typically used by system services and need admin access to bind on such a port.

If the receiver sends packet to the hard-coded port it's listening to (e.g. port 57) and the sender is on the same machine then you would create a loopback to the receiver itself. Always use the port specified from the packet and in case of production software would need a check in any case to prevent such a case.

Another reason a packet won't get to destination is the wrong IP address specified in the sender. UDP unlike TCP will attempt to send out a packet even if the address is unreachable and the sender will not receive an error indication. You can check this by printing the address in the receiver as a precaution for debugging.

In the sender you set:

 byte [] IP= { (byte)192, (byte)168, 1, 106 };
 InetAddress address = InetAddress.getByAddress(IP);

but might be simpler to use the address in string form:

 InetAddress address = InetAddress.getByName("");

In other words, you set target as If this is not the receiver then you won't get the packet.

Here's a simple UDP Receiver that works :


public class Receiver {

    public static void main(String[] args) {
        int port = args.length == 0 ? 57 : Integer.parseInt(args[0]);
        new Receiver().run(port);

    public void run(int port) {    
      try {
        DatagramSocket serverSocket = new DatagramSocket(port);
        byte[] receiveData = new byte[8];
        String sendString = "polo";
        byte[] sendData = sendString.getBytes("UTF-8");

        System.out.printf("Listening on udp:%s:%d%n",
                InetAddress.getLocalHost().getHostAddress(), port);     
        DatagramPacket receivePacket = new DatagramPacket(receiveData,

              String sentence = new String( receivePacket.getData(), 0,
                                 receivePacket.getLength() );
              System.out.println("RECEIVED: " + sentence);
              // now send acknowledgement packet back to sender     
              DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length,
                   receivePacket.getAddress(), receivePacket.getPort());
      } catch (IOException e) {
      // should close serverSocket in finally block

Latex Remove Spaces Between Items in List

It's easier with the enumitem package:

Less space:
  \item foo
  \item bar
  \item baz

Even more compact:
  \item foo
  \item bar
  \item baz


The enumitem package provides a lot of features to customize bullets, numbering and lengths.

The paralist package provides very compact lists: compactitem, compactenum and even lists within paragraphs like inparaenum and inparaitem.

Can I call a constructor from another constructor (do constructor chaining) in C++?

In C++11, a constructor can call another constructor overload:

class Foo  {
     int d;         
    Foo  (int i) : d(i) {}
    Foo  () : Foo(42) {} //New to C++11

Additionally, members can be initialized like this as well.

class Foo  {
     int d = 5;         
    Foo  (int i) : d(i) {}

This should eliminate the need to create the initialization helper method. And it is still recommended not calling any virtual functions in the constructors or destructors to avoid using any members that might not be initialized.

Postgresql query between date ranges

From PostreSQL 9.2 Range Types are supported. So you can write this like:

SELECT user_id
FROM user_logs
WHERE '[2014-02-01, 2014-03-01]'::daterange @> login_date

this should be more efficient than the string comparison

Onclick javascript to make browser go back to previous page?

<input name="action" type="submit" value="Cancel" onclick="window.history.back();"/> 

React Router with optional path parameter

If you are looking to do an exact match, use the following syntax: (param)?.


<Route path={`my/(exact)?/path`} component={MyComponent} />

The nice thing about this is that you'll have props.match to play with, and you don't need to worry about checking the value of the optional parameter:

{ props: { match: { "0": "exact" } } }

How can I use async/await at the top level?

i like this clever syntax to do async work from an entrypoint

void async function main() {
  await doSomeWork()
  await doMoreWork()

How do I block or restrict special characters from input fields with jquery?

Allow only numbers in TextBox (Restrict Alphabets and Special Characters)

        /*code: 48-57 Numbers
          8  - Backspace,
          35 - home key, 36 - End key
          37-40: Arrow keys, 46 - Delete key*/
        function restrictAlphabets(e){
            var x=e.which||e.keycode;
            if((x>=48 && x<=57) || x==8 ||
                (x>=35 && x<=40)|| x==46)
                return true;
                return false;

How to easily duplicate a Windows Form in Visual Studio?

  1. Copy and paste the form.
  2. Rename the pasted form .cs to match the new form class name. This should auto rename other related files.
  3. Open up .cs file. Change the class name and the name of the constructor(s) and destructor.
  4. Open up .Designer.cs file and change the class name.

Extra Credit:

  1. Consider abstracting common functionality from the form into common form or controls.

Tree data structure in C#

My best advice would be that there is no standard tree data structure because there are so many ways you could implement it that it would be impossible to cover all bases with one solution. The more specific a solution, the less likely it is applicable to any given problem. I even get annoyed with LinkedList - what if I want a circular linked list?

The basic structure you'll need to implement will be a collection of nodes, and here are some options to get you started. Let's assume that the class Node is the base class of the entire solution.

If you need to only navigate down the tree, then a Node class needs a List of children.

If you need to navigate up the tree, then the Node class needs a link to its parent node.

Build an AddChild method that takes care of all the minutia of these two points and any other business logic that must be implemented (child limits, sorting the children, etc.)

How to show row number in Access query like ROW_NUMBER in SQL

One way to do this with MS Access is with a subquery but it does not have anything like the same functionality:

       (SELECT Count(ID) 
        FROM table1 b WHERE b.ID <= a.ID 
        AND b.AText Like "*a*") AS RowNo
FROM Table1 AS a
WHERE a.AText Like "*a*"

'invalid value encountered in double_scalars' warning, possibly numpy

I ran into similar problem - Invalid value encountered in ... After spending a lot of time trying to figure out what is causing this error I believe in my case it was due to NaN in my dataframe. Check out working with missing data in pandas.

None == None True

np.nan == np.nan False

When NaN is not equal to NaN then arithmetic operations like division and multiplication causes it throw this error.

Couple of things you can do to avoid this problem:

  1. Use pd.set_option to set number of decimal to consider in your analysis so an infinitesmall number does not trigger similar problem - ('display.float_format', lambda x: '%.3f' % x).

  2. Use df.round() to round the numbers so Panda drops the remaining digits from analysis. And most importantly,

  3. Set NaN to zero df=df.fillna(0). Be careful if Filling NaN with zero does not apply to your data sets because this will treat the record as zero so N in the mean, std etc also changes.

How to Deserialize JSON data?

You can write your own JSON parser and make it more generic based on your requirement. Here is one which served my purpose nicely, hope will help you too.

class JsonParsor
    public static DataTable JsonParse(String rawJson)
        DataTable dataTable = new DataTable();
        Dictionary<string, string> outdict = new Dictionary<string, string>();
        StringBuilder keybufferbuilder = new StringBuilder();
        StringBuilder valuebufferbuilder = new StringBuilder();
        StringReader bufferreader = new StringReader(rawJson);
        int s = 0;
        bool reading = false;
        bool inside_string = false;
        bool reading_value = false;
        bool reading_number = false;
        while (s >= 0)
            s = bufferreader.Read();
            //open JSON
            if (!reading)
                if ((char)s == '{' && !inside_string && !reading)
                    reading = true;
                if ((char)s == '}' && !inside_string && !reading)
                if ((char)s == ']' && !inside_string && !reading)
                if ((char)s == ',')
                if (reading_value)
                    if (!inside_string && (char)s >= '0' && (char)s <= '9')
                        reading_number = true;
                //if we find a quote and we are not yet inside a string, advance and get inside
                if (!inside_string)
                    if ((char)s == '\"' && !inside_string)
                        inside_string = true;
                    if ((char)s == '[' && !inside_string)
                        keybufferbuilder.Length = 0;
                        valuebufferbuilder.Length = 0;
                                reading = false;
                                inside_string = false;
                                reading_value = false;
                    if ((char)s == ',' && !inside_string && reading_number)
                        if (!dataTable.Columns.Contains(keybufferbuilder.ToString()))
                            dataTable.Columns.Add(keybufferbuilder.ToString(), typeof(string));
                        if (!outdict.ContainsKey(keybufferbuilder.ToString()))
                            outdict.Add(keybufferbuilder.ToString(), valuebufferbuilder.ToString());
                        keybufferbuilder.Length = 0;
                        valuebufferbuilder.Length = 0;
                        reading_value = false;
                        reading_number = false;

                //if we reach end of the string
                if (inside_string)
                    if ((char)s == '\"')
                        inside_string = false;
                        s = bufferreader.Read();
                        if ((char)s == ':')
                            reading_value = true;
                        if (reading_value && (char)s == ',')
                            //put the key-value pair into dictionary
                            if (!outdict.ContainsKey(keybufferbuilder.ToString()))
                            outdict.Add(keybufferbuilder.ToString(), valuebufferbuilder.ToString());
                            keybufferbuilder.Length = 0;
                            valuebufferbuilder.Length = 0;
                            reading_value = false;
                        if (reading_value && (char)s == '}')
                            if (!dataTable.Columns.Contains(keybufferbuilder.ToString()))
                                dataTable.Columns.Add(keybufferbuilder.ToString(), typeof(string));
                            if (!outdict.ContainsKey(keybufferbuilder.ToString()))
                                outdict.Add(keybufferbuilder.ToString(), valuebufferbuilder.ToString());
                            ICollection key = outdict.Keys;
                            DataRow newrow = dataTable.NewRow();
                            foreach (string k_loopVariable in key)
                                newrow[k_loopVariable] = outdict[k_loopVariable];
                            CommonModule.LogTheMessage(dataTable.Rows.Count.ToString(), "", "row_count", "");
                            reading_value = false;
                            reading = false;
                        if (reading_value)
                    switch ((char)s)
                        case ':':
                            reading_value = true;
                            if (reading_value)

        return dataTable;

When I run `npm install`, it returns with `ERR! code EINTEGRITY` (npm 5.3.0)


This worked for me:
npm cache verify

Then I re-ran:
npm install -g create-react-app

And it installed as expected: Issue resolved.

Other solutions mentioned in the GitHub issue include:

npm cache clean --force


Deleting npm and npm-cache folders in Users%username%\AppData\Roaming (windows 7) and running npm install


Update npm by via npm i -g npm


Delete package-lock.json


npm cache clean


Do these steps to fix the problem:

  1. Find all outdated packages and update theme:
    npm outdated -g
    sudo npm i -g outDatedPKG
  2. Upgrade npm to latest version with:
    sudo npm i -g npm
  3. Delete package-lock.json file.
  4. Delete _cacache directory in ~/.npm: npm cache verify
  5. Every time I get that error, do steps 2 & 3.
  6. If you still get the error, clear npm's cache:
    npm cache clean --force


  1. Add proxy to .npmrc in ~ directory:


  1. Try again! slow internet connection and censorship may cause this ugly problem.


npm cache clear --force && npm install --no-shrinkwrap --update-binary


npm config set package-lock false

How to wait for all threads to finish, using ExecutorService?

I've just written a sample program that solves your problem. There was no concise implementation given, so I'll add one. While you can use executor.shutdown() and executor.awaitTermination(), it is not the best practice as the time taken by different threads would be unpredictable.

ExecutorService es = Executors.newCachedThreadPool();
    List<Callable<Integer>> tasks = new ArrayList<>();

    for (int j = 1; j <= 10; j++) {
        tasks.add(new Callable<Integer>() {

            public Integer call() throws Exception {
                int sum = 0;
                System.out.println("Starting Thread "
                        + Thread.currentThread().getId());

                for (int i = 0; i < 1000000; i++) {
                    sum += i;

                System.out.println("Stopping Thread "
                        + Thread.currentThread().getId());
                return sum;


    try {
        List<Future<Integer>> futures = es.invokeAll(tasks);
        int flag = 0;

        for (Future<Integer> f : futures) {
            Integer res = f.get();
            System.out.println("Sum: " + res);
            if (!f.isDone()) 
                flag = 1;

        if (flag == 0)

    } catch (InterruptedException | ExecutionException e) {

Parallel.ForEach vs Task.Factory.StartNew

Parallel.ForEach will optimize(may not even start new threads) and block until the loop is finished, and Task.Factory will explicitly create a new task instance for each item, and return before they are finished (asynchronous tasks). Parallel.Foreach is much more efficient.

Python script header

From the manpage for env (GNU coreutils 6.10):

env - run a program in a modified environment

In theory you could use env to reset the environment (removing many of the existing environment variables) or add additional environment variables in the script header. Practically speaking, the two versions you mentioned are identical. (Though others have mentioned a good point: specifying python through env lets you abstractly specify python without knowing its path.)

"java.lang.OutOfMemoryError : unable to create new native Thread"

To find which processes are creating threads try:

ps huH

I normally redirect output to a file and analysis the file offline (is thread count for each process is as expected or not)

Insert data into table with result from another select query

INSERT INTO `test`.`product` ( `p1`, `p2`, `p3`) 
SELECT sum(p1), sum(p2), sum(p3) 
FROM `test`.`product`;

Convert date to datetime in Python

One way to convert from date to datetime that hasn't been mentioned yet:

from datetime import date, datetime
d =
datetime.strptime(d.strftime('%Y%m%d'), '%Y%m%d')

how to dynamically add options to an existing select in vanilla javascript

Use the document.createElement function and then add it as a child of your select.

var newOption = document.createElement("option");
newOption.text = 'the options text';
newOption.value = 'some value if you want it';

How to generate components in a specific folder with Angular CLI?

Firstly to create a Component you need to use:-

  • ng g c componentname

    By using above command New Component will be created in a folder with
    (componentname) you specified above.

But if you need to create a component inside of another component or in specific folder:-

  • ng g c componentname/newComponentName

MongoDB vs Firebase

Firebase provides some good features like real time change reflection , easy integration of authentication mechanism , and lots of other built-in features for rapid web development. Firebase, really makes Web development so simple that never exists. Firebase database is a fork of MongoDB.

What's the advantage of using Firebase over MongoDB?

You can take advantage of all built-in features of Firebase over MongoDB.

Printing a java map Map<String, Object> - How?

I'm sure there's some nice library that does this sort of thing already for you... But to just stick with the approach you're already going with, Map#entrySet gives you a combined Object with the key and the value. So something like:

for (Map.Entry<String, Object> entry : map.entrySet()) {
    System.out.println(entry.getKey() + ":" + entry.getValue().toString());

will do what you're after.

If you're using java 8, there's also the new streaming approach.

map.forEach((key, value) -> System.out.println(key + ":" + value));

Removing duplicates from a SQL query (not just "use distinct")

If I understand you correctly, you want to list to exclude duplicates on one column only, inner join to a sub-select

select u.* [whatever joined values]
from users u
inner join
(select name from users group by name having count(*)=1) uniquenames
on =

php - insert a variable in an echo string

$i = 1;

echo "<p class='paragraph{$i}'></p>"; 


java.sql.SQLException: Fail to convert to internal representation

Your data types are mismatched when you are retrieving the field values.

Also check how you store your enums, default is ORDINAL (numeric value stored in database), but STRING (name of enum stored in database) is also an option. Make sure the Entity in your code and the Model in your database are exactly the same.

I had an enum mismatch. It was set to default (ORDINAL) but the database model was expecting a string VARCHAR2(100char). Solution: @Enumerated(EnumType.STRING)

How can I display a pdf document into a Webview?

Download source code from here (Open pdf in webview android)


<RelativeLayout android:layout_width="match_parent"


package com.pdfwebview;

import android.os.Bundle;
import android.view.View;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends AppCompatActivity {

    WebView webview;
    ProgressDialog pDialog;

    protected void onCreate(Bundle savedInstanceState) {


    private void init() {

        webview = (WebView) findViewById(;

        pDialog = new ProgressDialog(MainActivity.this);


    private void listener() {
        webview.setWebViewClient(new WebViewClient() {
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                super.onPageStarted(view, url, favicon);

            public void onPageFinished(WebView view, String url) {
                super.onPageFinished(view, url);

Java: random long number in 0 <= x < n range

Starting from Java 7 (or Android API Level 21 = 5.0+) you could directly use ThreadLocalRandom.current().nextLong(n) (for 0 = x < n) and ThreadLocalRandom.current().nextLong(m, n) (for m = x < n). See @Alex's answer for detail.

If you are stuck with Java 6 (or Android 4.x) you need to use an external library (e.g. org.apache.commons.math3.random.RandomDataGenerator.getRandomGenerator().nextLong(0, n-1), see @mawaldne's answer), or implement your own nextLong(n).

According to nextInt is implemented as

 public int nextInt(int n) {
     if (n<=0)
                throw new IllegalArgumentException("n must be positive");

     if ((n & -n) == n)  // i.e., n is a power of 2
         return (int)((n * (long)next(31)) >> 31);

     int bits, val;
     do {
         bits = next(31);
         val = bits % n;
     } while(bits - val + (n-1) < 0);
     return val;

So we may modify this to perform nextLong:

long nextLong(Random rng, long n) {
   // error checking and 2^x checking removed for simplicity.
   long bits, val;
   do {
      bits = (rng.nextLong() << 1) >>> 1;
      val = bits % n;
   } while (bits-val+(n-1) < 0L);
   return val;

How to easily resize/optimize an image size with iOS?

I ended up using Brads technique to create a scaleToFitWidth method in UIImage+Extensions if that's useful to anyone...

-(UIImage *)scaleToFitWidth:(CGFloat)width
    CGFloat ratio = width / self.size.width;
    CGFloat height = self.size.height * ratio;

    NSLog(@"W:%f H:%f",width,height);

    UIGraphicsBeginImageContext(CGSizeMake(width, height));
    [self drawInRect:CGRectMake(0.0f,0.0f,width,height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

    return newImage;

then wherever you like

#import "UIImage+Extensions.h"

UIImage *newImage = [image scaleToFitWidth:100.0f];

Also worth noting you could move this further down into a UIView+Extensions class if you want to render images from a UIView

push multiple elements to array

Now in ECMAScript2015 (a.k.a. ES6), you can use the spread operator to append multiple items at once:

var arr = [1];_x000D_
var newItems = [2, 3];_x000D_

See Kangax's ES6 compatibility table to see what browsers are compatible

How can I get LINQ to return the object which has the max value for a given property?

In case you don't want to use MoreLINQ and want to get linear time, you can also use Aggregate:

var maxItem = 
    new { Max = Int32.MinValue, Item = (Item)null },
    (state, el) => (el.ID > state.Max) 
      ? new { Max = el.ID, Item = el } : state).Item;

This remembers the current maximal element (Item) and the current maximal value (Item) in an anonymous type. Then you just pick the Item property. This is indeed a bit ugly and you could wrap it into MaxBy extension method to get the same thing as with MoreLINQ:

public static T MaxBy(this IEnumerable<T> items, Func<T, int> f) {
  return items.Aggregate(
    new { Max = Int32.MinValue, Item = default(T) },
    (state, el) => {
      var current = f(el.ID);
      if (current > state.Max) 
        return new { Max = current, Item = el };
        return state; 

Can the jQuery UI Datepicker be made to disable Saturdays and Sundays (and holidays)?

There is the beforeShowDay option, which takes a function to be called for each date, returning true if the date is allowed or false if it is not. From the docs:


The function takes a date as a parameter and must return an array with [0] equal to true/false indicating whether or not this date is selectable and 1 equal to a CSS class name(s) or '' for the default presentation. It is called for each day in the datepicker before is it displayed.

Display some national holidays in the datepicker.

$(".selector").datepicker({ beforeShowDay: nationalDays})   

natDays = [
  [1, 26, 'au'], [2, 6, 'nz'], [3, 17, 'ie'],
  [4, 27, 'za'], [5, 25, 'ar'], [6, 6, 'se'],
  [7, 4, 'us'], [8, 17, 'id'], [9, 7, 'br'],
  [10, 1, 'cn'], [11, 22, 'lb'], [12, 12, 'ke']

function nationalDays(date) {
    for (i = 0; i < natDays.length; i++) {
      if (date.getMonth() == natDays[i][0] - 1
          && date.getDate() == natDays[i][1]) {
        return [false, natDays[i][2] + '_day'];
  return [true, ''];

One built in function exists, called noWeekends, that prevents the selection of weekend days.

$(".selector").datepicker({ beforeShowDay: $.datepicker.noWeekends })

To combine the two, you could do something like (assuming the nationalDays function from above):

$(".selector").datepicker({ beforeShowDay: noWeekendsOrHolidays})   

function noWeekendsOrHolidays(date) {
    var noWeekend = $.datepicker.noWeekends(date);
    if (noWeekend[0]) {
        return nationalDays(date);
    } else {
        return noWeekend;

Update: Note that as of jQuery UI 1.8.19, the beforeShowDay option also accepts an optional third paremeter, a popup tooltip

How do I find the length/number of items present for an array?

Do you mean how long is the array itself, or how many customerids are in it?

Because the answer to the first question is easy: 5 (or if you don't want to hard-code it, Ben Stott's answer).

But the answer to the other question cannot be automatically determined. Presumably you have allocated an array of length 5, but will initially have 0 customer IDs in there, and will put them in one at a time, and your question is, "how many customer IDs have I put into the array?"

C can't tell you this. You will need to keep a separate variable, int numCustIds (for example). Every time you put a customer ID into the array, increment that variable. Then you can tell how many you have put in.

How to list the certificates stored in a PKCS12 keystore with keytool?

You can also use openssl to accomplish the same thing:

$ openssl pkcs12 -nokeys -info \
    -in </path/to/file.pfx> \
    -passin pass:<pfx's password>

MAC Iteration 2048
MAC verified OK
PKCS7 Encrypted data: pbeWithSHA1And40BitRC2-CBC, Iteration 2048
Certificate bag
Bag Attributes
    localKeyID: XX XX XX XX XX XX XX XX XX XX XX XX XX 48 54 A0 47 88 1D 90
    friendlyName: jedis-server
subject=/C=US/ST=NC/L=Raleigh/O=XXX Security/OU=XXX/CN=something1
issuer=/C=US/ST=NC/L=Raleigh/O=XXX Security/OU=XXXX/CN=something1
PKCS7 Data
Shrouded Keybag: pbeWithSHA1And3-KeyTripleDES-CBC, Iteration 2048

Accessing constructor of an anonymous class

If you dont need to pass arguments, then initializer code is enough, but if you need to pass arguments from a contrcutor there is a way to solve most of the cases:

Boolean var= new anonymousClass(){
    private String myVar; //String for example

    @Overriden public Boolean method(int i){
          //use myVar and i
    public String setVar(String var){myVar=var; return this;} //Returns self instane

Remove insignificant trailing zeros from a number?

I needed to solve this problem too when Django was displaying Decimal type values in a text field. E.g. when '1' was the value. It would show '1.00000000'. If '1.23' was the value, it would show '1.23000000' (In the case of a 'decimal_places' setting of 8)

Using parseFloat was not an option for me since it is possible it does not return the exact same value. toFixed was not an option since I did not want to round anything, so I created a function:

function removeTrailingZeros(value) {
    value = value.toString();

    # if not containing a dot, we do not need to do anything
    if (value.indexOf('.') === -1) {
        return value;

    # as long as the last character is a 0 or a dot, remove it
    while((value.slice(-1) === '0' || value.slice(-1) === '.') && value.indexOf('.') !== -1) {
        value = value.substr(0, value.length - 1);
    return value;

How do I determine file encoding in OS X?

Using file command with the --mime-encoding option (e.g. file --mime-encoding some_file.txt) instead of the -I option works on OS X and has the added benefit of omitting the mime type, "text/plain", which you probably don't care about.

Good font for code presentations?

  • Lucida Console (good, but a little short)
  • Lucida Sans Typewriter (taller, smaller character set)
  • Andale Mono is very clear

But this has been answered here before.

Laravel - Eloquent "Has", "With", "WhereHas" - What do they mean?

Document has already explain the usage. So I am using SQL to explain these methods


Assuming there is an Order (orders) has many OrderItem (order_items).

And you have already build the relationship between them.

// App\Models\Order:
public function orderItems() {
    return $this->hasMany('App\Models\OrderItem', 'order_id', 'id');

These three methods are all based on a relationship.


Result: with() return the model object and its related results.

Advantage: It is eager-loading which can prevent the N+1 problem.

When you are using the following Eloquent Builder:


Laravel change this code to only two SQL:

// get all orders:
SELECT * FROM orders; 

// get the order_items based on the orders' id above
SELECT * FROM order_items WHERE order_items.order_id IN (1,2,3,4...);

And then laravel merge the results of the second SQL as different from the results of the first SQL by foreign key. At last return the collection results.

So if you selected columns without the foreign_key in closure, the relationship result will be empty:

Order::with(['orderItems' => function($query) { 
           // $query->sum('quantity');
           $query->select('quantity'); // without `order_id`

#=> result:
[{  id: 1,
    code: '00001',
    orderItems: [],    // <== is empty
    id: 2,
    code: '00002',
    orderItems: [],    // <== is empty


Has will return the model's object that its relationship is not empty.


Laravel change this code to one SQL:

select * from `orders` where exists (
    select * from `order_items` where `order`.`id` = `order_item`.`order_id`


whereHas and orWhereHas methods to put where conditions on your has queries. These methods allow you to add customized constraints to a relationship constraint.

Order::whereHas('orderItems', function($query) {
   $query->where('status', 1);

Laravel change this code to one SQL:

select * from `orders` where exists (
    select * 
    from `order_items` 
    where `orders`.`id` = `order_items`.`order_id` and `status` = 1

Vector of Vectors to create matrix

As it is, both dimensions of your vector are 0.

Instead, initialize the vector as this:

vector<vector<int> > matrix(RR);
for ( int i = 0 ; i < RR ; i++ )

This will give you a matrix of dimensions RR * CC with all elements set to 0.

How to correctly dismiss a DialogFragment?

Kotlin Version of Terel answer

(fragmentManager.findFragmentByTag(TAG) as? DialogFragment)?.dismiss()

String Padding in C

#include <stdio.h>
#include <string.h>

int main(void) {
    char buf[BUFSIZ] = { 0 };
    char str[] = "Hello";
    char fill = '#';
    int width = 20; /* or whatever you need but less than BUFSIZ ;) */

    printf("%s%s\n", (char*)memset(buf, fill, width - strlen(str)), str);

    return 0;


$ gcc -Wall -ansi -pedantic padding.c
$ ./a.out 

How do I change the number of open files limit in Linux?

1) Add the following line to /etc/security/limits.conf

webuser hard nofile 64000

then login as webuser

su - webuser

2) Edit following two files for webuser

append .bashrc and .bash_profile file by running

echo "ulimit -n 64000" >> .bashrc ; echo "ulimit -n 64000" >> .bash_profile

3) Log out, then log back in and verify that the changes have been made correctly:

$ ulimit -a | grep open
open files                      (-n) 64000

Thats it and them boom, boom boom.

How to select a radio button by default?

This doesn't exactly answer the question but for anyone using AngularJS trying to achieve this, the answer is slightly different. And actually the normal answer won't work (at least it didn't for me).

Your html will look pretty similar to the normal radio button:

<input type='radio' name='group' ng-model='mValue' value='first' />First
<input type='radio' name='group' ng-model='mValue' value='second' /> Second

In your controller you'll have declared the mValue that is associated with the radio buttons. To have one of these radio buttons preselected, assign the $scope variable associated with the group to the desired input's value:


This makes the "second" radio button selected on loading the page.

EDIT: Since AngularJS 2.x

The above approach does not work if you're using version 2.x and above. Instead use ng-checked attribute as follows:

<input type='radio' name='gender' ng-model='genderValue' value='male' ng-checked='genderValue === male'/>Male
<input type='radio' name='gender' ng-model='genderValue' value='female' ng-checked='genderValue === female'/> Female

Aggregate / summarize multiple variables per group (e.g. sum, mean)

Interestingly, base R aggregate's data.frame method is not showcased here, above the formula interface is used, so for completeness:

  x = df1[c("x1", "x2")],
  by = df1[c("year", "month")],
  FUN = sum, na.rm = TRUE

More generic use of aggregate's data.frame method:

Since we are providing a

  • data.frame as x and
  • a list (data.frame is also a list) as by, this is very useful if we need to use it in a dynamic manner, e.g. using other columns to be aggregated and to aggregate by is very simple
  • also with custom-made aggregation functions

For example like so:

colsToAggregate <- c("x1")
aggregateBy <- c("year", "month")
dummyaggfun <- function(v, na.rm = TRUE) {
  c(sum = sum(v, na.rm = na.rm), mean = mean(v, na.rm = na.rm))

aggregate(df1[colsToAggregate], by = df1[aggregateBy], FUN = dummyaggfun)

MVC If statement in View

Every time you use html syntax you have to start the next razor statement with a @. So it should be @if ....

How to remove files that are listed in the .gitignore but still on the repository?

I did a very straightforward solution by manipulating the output of the .gitignore statement with sed:

cat .gitignore | sed '/^#.*/ d' | sed '/^\s*$/ d' | sed 's/^/git rm -r /' | bash


  1. print the .gitignore file
  2. remove all comments from the print
  3. delete all empty lines
  4. add 'git rm -r ' to the start of the line
  5. execute every line.

Calculating the difference between two Java date instances

Just to answer the initial question:

Put the following code in a Function like Long getAge(){}

Date dahora = new Date();
long MillisToYearsByDiv = 1000l *60l * 60l * 24l * 365l;
long javaOffsetInMillis = 1990l * MillisToYearsByDiv;
long realNowInMillis = dahora.getTime() + javaOffsetInMillis;
long realBirthDayInMillis = this.getFechaNac().getTime() + javaOffsetInMillis;
long ageInMillis = realNowInMillis - realBirthDayInMillis;

return ageInMillis / MillisToYearsByDiv;

The most important here is to work with long numbers when multiplying and dividing. And of course, the offset that Java applies in its calculus of Dates.


Are there any Java method ordering conventions?

  1. Class (static) variables: First the public class variables, then the protected, and then the private.

  2. Instance variables: First public, then protected, and then private.

  3. Constructors

  4. Methods: These methods should be grouped by functionality rather than by scope or accessibility. For example, a private class method can be in between two public instance methods. The goal is to make reading and understanding the code easier.


Error: ANDROID_HOME is not set and "android" command not in your PATH. You must fulfill at least one of these conditions.

You just need to type a command in flutter_console.bat type flutter config --android-sdk <path-to-your-android-sdk-path>

How to resolve merge conflicts in Git repository?

I am using Microsoft's Visual Code for resolving conflicts. Its very simple to use. I keep my project open in the workspace. It detects and highlights conflicts, moreover give GUI options to select whatever change I want to keep from HEAD or incoming. enter image description here

How to save an image locally using Python whose URL address I already know?

This can be done with requests. Load the page and dump the binary content to a file.

import os
import requests

url = ''
page = requests.get(url)

f_ext = os.path.splitext(url)[-1]
f_name = 'img{}'.format(f_ext)
with open(f_name, 'wb') as f:

Accidentally committed .idea directory files into git

Add .idea directory to the list of ignored files

First, add it to .gitignore, so it is not accidentally committed by you (or someone else) again:


Remove it from repository

Second, remove the directory only from the repository, but do not delete it locally. To achieve that, do what is listed here:

Remove a file from a Git repository without deleting it from the local filesystem

Send the change to others

Third, commit the .gitignore file and the removal of .idea from the repository. After that push it to the remote(s).


The full process would look like this:

$ echo '.idea' >> .gitignore
$ git rm -r --cached .idea
$ git add .gitignore
$ git commit -m '(some message stating you added .idea to ignored entries)'
$ git push

(optionally you can replace last line with git push some_remote, where some_remote is the name of the remote you want to push to)

CodeIgniter 500 Internal Server Error

This works fine for me

<IfModule mod_rewrite.c>
  RewriteEngine On
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ index.php?/$1 [L]
</IfModule >

How to obtain a Thread id in Python?

You can get the ident of the current running thread. The ident could be reused for other threads, if the current thread ends.

When you crate an instance of Thread, a name is given implicit to the thread, which is the pattern: Thread-number

The name has no meaning and the name don't have to be unique. The ident of all running threads is unique.

import threading

def worker():

threading.Thread(target=worker, name='foo').start()

The function threading.current_thread() returns the current running thread. This object holds the whole information of the thread.

Copy text from nano editor to shell

Simply use Ctrl+Shift+6 to copy current line or you can set mark using Ctrl+6 and copy multiple lines using above command as well.

How to HTML encode/escape a string? Is there a built-in?

The h helper method:

<%=h "<p> will be preserved" %>

Inserting one list into another list in java?

100, it will hold the same references. Therefore if you make a change to a specific object in the list, it will affect the same object in anotherList.

Adding or removing objects in any of the list will not affect the other.

list and anotherList are two different instances, they only hold the same references of the objects "inside" them.

How do I log a Python error with debug information?

A clean way to do it is using format_exc() and then parse the output to get the relevant part:

from traceback import format_exc

except Exception:
    print 'the relevant part is: '+format_exc().split('\n')[-2]


How to make a browser display a "save as dialog" so the user can save the content of a string to a file on his system?

In case anyone is still wondering...

I did it like this:

<a href="data:application/xml;charset=utf-8,your code here" download="filename.html">Save</a>

cant remember my source but it uses the following techniques\features:

  1. html5 download attribute
  2. data uri's

Found the reference:

EDIT: As you can gather from the comments this does NOT work in

  1. Internet Explorer (works in Edge v13 though)
  2. iOS Safari
  3. Opera Mini

How to display with n decimal places in Matlab

You can convert a number to a string with n decimal places using the SPRINTF command:

>> x = 1.23;
>> sprintf('%0.6f', x)

ans =


>> x = 1.23456789;
>> sprintf('%0.6f', x)

ans =


Use Excel VBA to click on a button in Internet Explorer, when the button has no "name" associated

CSS selector:

Use a CSS selector of img[src='images/toolbar/b_edit.gif']

This says select element(s) with img tag with attribute src having value of 'images/toolbar/b_edit.gif'

CSS query:

CSS query


You can apply the selector with the .querySelector method of document.


Angular JS Uncaught Error: [$injector:modulerr]

Try adding this:

<script src=""></script>

How to impose maxlength on textArea in HTML using JavaScript

Small problem with code above is that val() does not trigger change() event, so if you using backbone.js (or another frameworks for model binding), model won't be updated.

I'm posting the solution worked great for me.

$(function () {

    $(document).on('keyup', '.ie8 textarea[maxlength], .ie9 textarea[maxlength]', function (e) {
        var maxLength = $(this).attr('maxlength');
        if (e.keyCode > 47 && $(this).val().length >= maxLength) {
            $(this).val($(this).val().substring(0, maxLength)).trigger('change');
        return true;


Getting the first character of a string with $str[0]

Speaking as a mere mortal, I would stick with $str[0]. As far as I'm concerned, it's quicker to grasp the meaning of $str[0] at a glance than substr($str, 0, 1). This probably boils down to a matter of preference.

As far as performance goes, well, profile profile profile. :) Or you could peer into the PHP source code...

How to convert milliseconds into a readable date?

You can use datejs and convert in different formate. I have tested some formate and working fine.

var d = new Date(1469433907836);

d.toLocaleString()     // 7/25/2016, 1:35:07 PM
d.toLocaleDateString() // 7/25/2016
d.toDateString()       // Mon Jul 25 2016
d.toTimeString()       // 13:35:07 GMT+0530 (India Standard Time)
d.toLocaleTimeString() // 1:35:07 PM
d.toISOString();       // 2016-07-25T08:05:07.836Z
d.toJSON();            // 2016-07-25T08:05:07.836Z
d.toString();          // Mon Jul 25 2016 13:35:07 GMT+0530 (India Standard Time)
d.toUTCString();       // Mon, 25 Jul 2016 08:05:07 GMT

Boolean operators ( &&, -a, ||, -o ) in Bash

Rule of thumb: Use -a and -o inside square brackets, && and || outside.

It's important to understand the difference between shell syntax and the syntax of the [ command.

  • && and || are shell operators. They are used to combine the results of two commands. Because they are shell syntax, they have special syntactical significance and cannot be used as arguments to commands.

  • [ is not special syntax. It's actually a command with the name [, also known as test. Since [ is just a regular command, it uses -a and -o for its and and or operators. It can't use && and || because those are shell syntax that commands don't get to see.

But wait! Bash has a fancier test syntax in the form of [[ ]]. If you use double square brackets, you get access to things like regexes and wildcards. You can also use shell operators like &&, ||, <, and > freely inside the brackets because, unlike [, the double bracketed form is special shell syntax. Bash parses [[ itself so you can write things like [[ $foo == 5 && $bar == 6 ]].

Difference between IsNullOrEmpty and IsNullOrWhiteSpace in C#

The first method checks if a string is null or a blank string. In your example you can risk a null reference since you are not checking for null before trimming

1- string.IsNullOrEmpty(text.Trim())

The second method checks if a string is null or an arbitrary number of spaces in the string (including a blank string)

2- string .IsNullOrWhiteSpace(text)

The method IsNullOrWhiteSpace covers IsNullOrEmpty, but it also returns true if the string contains white space.

In your concrete example you should use 2) as you run the risk of a null reference exception in approach 1) since you're calling trim on a string that may be null

TortoiseSVN Error: "OPTIONS of 'https://...' could not connect to server (...)"

This was driving me nuts and I solved it today. I'm posting in this old thread because I arrived here several times while searching for a solution. I hope it helps someone. For me, I checked svn-settings --> network --> Edit Subversion server file and found that there were some uncommented lines at the end:

http-proxy-host = 
ssl-trust-default-ca = no
http-proxy-username = 
http-proxy-password = 

that differed from my co-workers. Once I comment these, it started working again.

How to add header data in XMLHttpRequest when using formdata?

Use: xmlhttp.setRequestHeader(key, value);

How to emulate GPS location in the Android Emulator?

You can connect to the Emulator via Telnet. You then have a Emulator console that lets you enter certain data like geo fixes, network etc.

How to use the console is extensively explained here. To connect to the console open a command line and type

telnet localhost 5554

You then can use the geo command to set a latitude, longitude and if needed altitude on the device that is passed to all programs using the gps location provider. See the link above for further instructions.

The specific command to run in the console is

geo fix <longitude value> <latitude value>

I found this site useful for finding a realistic lat/lng:

If you need more then one coordinate you can use a kml file with a route as well it is a little bit described in this article. I can't find a better source at the moment.

How do I get information about an index and table owner in Oracle?

 select index_name, column_name
 from user_ind_columns
 where table_name = 'NAME';

OR use this:


And for Indexes:


Is there a library function for Root mean square error (RMSE) in python?

from sklearn import metrics
import bumpy as np

EditText request focus

>>you can write your code like

  if (TextUtils.isEmpty(username)) {
            editTextUserName.setError("Please enter username");

        if (TextUtils.isEmpty(password)) {
            editTextPassword.setError("Enter a password");

python variable NameError

This should do it:

#!/usr/local/cpython-2.7/bin/python  # offer users choice for how large of a song list they want to create # in order to determine (roughly) how many songs to copy print "\nHow much space should the random song list occupy?\n" print "1. 100Mb" print "2. 250Mb\n"  tSizeAns = int(raw_input())  if tSizeAns == 1:     tSize = "100Mb" elif tSizeAns == 2:     tSize = "250Mb" else:     tSize = "100Mb"    # in case user fails to enter either a 1 or 2  print "\nYou  want to create a random song list that is {}.".format(tSize) 

BTW, in case you're open to moving to Python 3.x, the differences are slight:

#!/usr/local/cpython-3.3/bin/python  # offer users choice for how large of a song list they want to create # in order to determine (roughly) how many songs to copy print("\nHow much space should the random song list occupy?\n") print("1. 100Mb") print("2. 250Mb\n")  tSizeAns = int(input())  if tSizeAns == 1:     tSize = "100Mb" elif tSizeAns == 2:     tSize = "250Mb" else:     tSize = "100Mb"    # in case user fails to enter either a 1 or 2  print("\nYou want to create a random song list that is {}.".format(tSize)) 


Java java.sql.SQLException: Invalid column index on preparing statement

In date '?', the '?' is a literal string with value ?, not a parameter placeholder, so your query does not have any parameters. The date is a shorthand cast from (literal) string to date. You need to replace date '?' with ? to actually have a parameter.

Also if you know it is a date, then use setDate(..) and not setString(..) to set the parameter.

Linux command (like cat) to read a specified quantity of characters

you could also grep the line out and then cut it like for instance:

grep 'text' filename | cut -c 1-5

How to include external Python code to use in other files?

You will need to import the other file as a module like this:

import Math

If you don't want to prefix your Calculate function with the module name then do this:

from Math import Calculate

If you want to import all members of a module then do this:

from Math import *

Edit: Here is a good chapter from Dive Into Python that goes a bit more in depth on this topic.

Ruby on Rails form_for select field with class

You can also add prompt option like this.

<%=, ['Item 1', 'Item 2'], {include_blank: "Select something"}, { :class => 'my_style_class' }) %>

django import error - No module named

Okay so it goes like this:

You have created a virtual environment and django module belongs to that environment only.Since virtualenv isolates itself from everything else,hence you are seeing this.

go through this for further assistance:

1.You can switch to the directory where your virtual environment is stored and then run the django module.

2.Alternatively you can install django globally to your python->site-packages by either running pip or easy_install

Command using pip: pip install django

then do this:

import django print (django.get_version()) (depending on which version of python you use.This for python 3+ series)

and then you can run this: python runserver and check on your web browser by typing :localhost:8000 and you should see django powered page.

Hope this helps.

How to run a command in the background and get no output?

Sorry this is a bit late but found the ideal solution for somple commands where you don't want any standard or error output (credit where it's due:

This redirects output to null and keeps screen clear:

command &>/dev/null &

How to create a responsive image that also scales up in Bootstrap 3

Bootstrap's responsive image class sets max-width to 100%. This limits its size, but does not force it to stretch to fill parent elements larger than the image itself. You'd have to use the width attribute to force upscaling.

How to get the current time in milliseconds from C in Linux?

This version need not math library and checked the return value of clock_gettime().

#include <time.h>
#include <stdlib.h>
#include <stdint.h>

 * @return milliseconds
uint64_t get_now_time() {
  struct timespec spec;
  if (clock_gettime(1, &spec) == -1) { /* 1 is CLOCK_MONOTONIC */

  return spec.tv_sec * 1000 + spec.tv_nsec / 1e6;

Gradients in Internet Explorer 9

Opera will soon start having builds available with gradient support, as well as other CSS features.

The W3C CSS Working Group is not even finished with CSS 2.1, y'all know that, right? We intend to be finished very soon. CSS3 is modularized precisely so we can move modules through to implementation faster rather than an entire spec.

Every browser company uses a different software cycle methodology, testing, and so on. So the process takes time.

I'm sure many, many readers well know that if you're using anything in CSS3, you're doing what's called "progressive enhancement" - the browsers with the most support get the best experience. The other part of that is "graceful degradation" meaning the experience will be agreeable but perhaps not the best or most attractive until that browser has implemented the module, or parts of the module that are relevant to what you want to do.

This creates quite an odd situation that unfortunately front-end devs get extremely frustrated by: inconsistent timing on implementations. So it's a real challenge on either side - do you blame the browser companies, the W3C, or worse yet - yourself (goodness knows we can't know it all!) Do those of us who are working for a browser company and W3C group members blame ourselves? You?

Of course not. It's always a game of balance, and as of yet, we've not as an industry figured out where that point of balance really is. That's the joy of working in evolutionary technology :)

How to initialize an array in Java?

You can do:

int[] data = {10,20,30,40,50,60,71,80,90,91};

How to install "ifconfig" command in my ubuntu docker image?

From within a Dockerfile something like the following should do the trick:

RUN apt-get update && \
     apt-get install -y net-tools

From memory it's best practice to combine the update and the package installation lines to prevent docker caching the update step which can result in out-dated packages being installed.

Installing it via the CLI or a shell script:

apt-get update && apt-get install net-tools

Converting list to *args when calling function

yes, using *arg passing args to a function will make python unpack the values in arg and pass it to the function.


>>> def printer(*args):
 print args

>>> printer(2,3,4)
(2, 3, 4)
>>> printer(*range(2, 5))
(2, 3, 4)
>>> printer(range(2, 5))
([2, 3, 4],)

How to execute a program or call a system command from Python

Check the "pexpect" Python library, too.

It allows for interactive controlling of external programs/commands, even ssh, ftp, telnet, etc. You can just type something like:

child = pexpect.spawn('ftp')

child.expect('(?i)name .*: ')



How to fix 'fs: re-evaluating native module sources is not supported' - graceful-fs

Just to point out that cordova brings in it's own npm with the graceful-fs dependency, so if you use Cordova make sure that it is the latest so you get the latest graceful-fs from that as well.

Error: Configuration with name 'default' not found in Android Studio

Add your library folder in your root location of your project and copy all the library files there. For ex YourProject/library then sync it and rest things seems OK to me.

Selected value for JSP drop down using JSTL

i tried the last answer from Sandeep Kumar, and i found way more simple :

<option value="1" <c:if test="${item.key == 1}"> selected </c:if>>

What does 'git blame' do?

The git blame command is used to know who/which commit is responsible for the latest changes made to a file. The author/commit of each line can also been seen.

git blame filename (commits responsible for changes for all lines in code)

git blame filename -L 0,10 (commits responsible for changes from line "0" to line "10")

There are many other options for blame, but generally these could help.

Syntax error "syntax error, unexpected end-of-input, expecting keyword_end (SyntaxError)"

It seems that you have a bunch of describes that never have ends keywords, starting with describe "when email format is invalid" do until describe "when email address is already taken" do

Put an end on those guys and you're probably done =)

Changing the Status Bar Color for specific ViewControllers using Swift in iOS8

In Swift 5 or xcode 11 and later set (View controller-based status bar appearance) key in info.plist as NO Then go to project target and select general, Set status bar style to dark or light

Auto Increment after delete in MySQL

You can use your mysql client software/script to specify where the primary key should start from after deleting the required records.

SQL WHERE ID IN (id1, id2, ..., idn)

An alternative approach might be to use another table to contain id values. This other table can then be inner joined on your TABLE to constrain returned rows. This will have the major advantage that you won't need dynamic SQL (problematic at the best of times), and you won't have an infinitely long IN clause.

You would truncate this other table, insert your large number of rows, then perhaps create an index to aid the join performance. It would also let you detach the accumulation of these rows from the retrieval of data, perhaps giving you more options to tune performance.

Update: Although you could use a temporary table, I did not mean to imply that you must or even should. A permanent table used for temporary data is a common solution with merits beyond that described here.

How to input matrix (2D list) in Python?

n=int(input("Provide me size of squre matrix row==column : "))
for i in range(n):
   for j in range(n):
    print("Here your {} column {}".format(i+1,a))
for m in range(n):

works perfectly

Easy way to prevent Heroku idling?

One more working solution: wokeDyno Here is a blog post how it works: It's integrated in the app very easy:

/* Example: as used with an Express app */

const express = require("express")
const wakeDyno = require("woke-dyno");

// create an Express app
const app = express();

// start the server, then call wokeDyno(url).start()
app.listen(PORT, () => {
    wakeDyno(DYNO_URL).start(); // DYNO_URL should be the url of your Heroku app

Display the current date and time using HTML and Javascript with scrollable effects in hta application

<div id="clockbox" style="font:14pt Arial; color:#FF0000;text-align: center; border:1px solid red;background:cyan; height:50px;padding-top:12px;"></div>

How to put a horizontal divisor line between edit text's in a activity

Use This..... You will love it

    android:text=" "

Unable to compile simple Java 10 / Java 11 project with Maven

Specify maven.compiler.source and target versions.

1) Maven version which supports jdk you use. In my case JDK 11 and maven 3.6.0.

2) pom.xml


As an alternative, you can fully specify maven compiler plugin. See previous answers. It is shorter in my example :)


3) rebuild the project to avoid compile errors in your IDE.

4) If it still does not work. In Intellij Idea I prefer using terminal instead of using terminal from OS. Then in Idea go to file -> settings -> build tools -> maven. I work with maven I downloaded from apache (by default Idea uses bundled maven). Restart Idea then and run mvn clean install again. Also make sure you have correct Path, MAVEN_HOME, JAVA_HOME environment variables.

I also saw this one-liner, but it does not work.


I made some quick starter projects, which I re-use in other my projects, feel free to check:

Add Custom Headers using HttpWebRequest

IMHO it is considered as malformed header data.

You actually want to send those name value pairs as the request content (this is the way POST works) and not as headers.

The second way is true.

How to change visibility of layout programmatically

Use this Layout in your xml file


Define your layout in .class file

 LinearLayout linearLayout = (LinearLayout) findViewById(;

Now if you want to display this layout just write


and if you want to hide layout just write


Add number of days to a date

You can add like this as well, if you want the date 5 days from a specific date :

You have a variable with a date like this (gotten from an input or DB or just hard coded):

$today = "2015-06-15"; // Or can put $today = date ("Y-m-d");

$fiveDays = date ("Y-m-d", strtotime ($today ."+5 days"));

echo $fiveDays; // Will output 2015-06-20

Convert comma separated string of ints to int array

I have found a simple solution which worked for me.


Using multiple parameters in URL in express

For what you want I would've used

    app.get('/fruit/:fruitName&:fruitColor', function(request, response) {
       const name = request.params.fruitName 
       const color = request.params.fruitColor 

or better yet

    app.get('/fruit/:fruit', function(request, response) {
       const fruit = request.params.fruit

where fruit is a object. So in the client app you just call{"name":"My fruit name", "color":"The color of the fruit"}

and as a response you should see:

    //  client side response
    // { name: My fruit name, color:The color of the fruit}

How to import NumPy in the Python shell

The message is fairly self-explanatory; your working directory should not be the NumPy source directory when you invoke Python; NumPy should be installed and your working directory should be anything but the directory where it lives.

How to select first and last TD in a row?

You could use the :first-child and :last-child pseudo-selectors:

tr td:first-child{
tr td:last-child {

Or you can use other way like

// To first child 
tr td:nth-child(1){

// To last child 
tr td:nth-last-child(1){

Both way are perfectly working Button OnClick event not firing

Try to go into Design mode in Visual Studio, locate the button and double click the button that should setup the event. Otherwise once the button is selected in Design more, go to the properties and try setting it from there.

Run cURL commands from Windows console

Currently in Windows 10 build 17063 and later, cURL comes by default with windows. Then you don't need to download it and just use curl.exe.

Test iOS app on device without apple developer program or jailbreak

Seven years after the inception of the App Store (July 10, 2008), Apple has finally introduced a new feature in Xcode 7 that allows you to deploy and run any number of apps on any of your devices, simply by logging in with your Apple ID. You will no longer need a paid Program membership to deploy apps on your own device (and you certainly no longer have to jailbreak your device if you're not comfortable doing so).

Well, not for the majority of use cases anyway. For obvious reasons, certain capabilities and entitlements that require Program membership such as Game Center and in-app purchases will not be available to apps deployed using this method. From Apple's developer documentation:

Launch Your App on Devices Using Free Provisioning (iOS, watchOS)

If you don’t join the Apple Developer Program, you can still build and run your app on your devices using free provisioning. However, the capabilities available to your app, described in Adding Capabilities, are restricted when you don’t belong to the Apple Developer Program.

The precise steps to getting your app onto your iOS device or Apple Watch follow immediately thus (screenshots omitted for ease of skimming):

  1. In Xcode, add your Apple ID to Accounts preferences, described in Adding Your Apple ID Account in Xcode.

  2. In the project navigator, select the project and your target to display the project editor.

  3. Click General and choose your name from the Team pop-up menu.

  4. Connect the device to your Mac and choose your device from the Scheme toolbar menu.

  5. Below the Team pop-up menu, click Fix Issue.

    Xcode creates a free provisioning profile for you and the warning text under the Team pop-up menu disappears.

  6. Click the Run button.

    Xcode installs the app on the device before launching the app.

Prior to Xcode 7, a Program membership was indeed required in order to sign the provisioning certificates required to deploy apps to devices. The only other alternative was jailbreaking. With Xcode 7, you no longer need to jailbreak your device just to run apps distributed outside the App Store, or to test apps if you cannot afford to join the Program, or to deploy and use apps that you have developed for your own personal use if you do not intend to distribute them through the App Store (in which case you probably don't need the entitlements offered by Program membership anyway).

How can I selectively merge or pick changes from another branch in Git?

I had the exact same problem as mentioned by you above. But I found this clearer in explaining the answer.


  • Check out the path(s) from the branch you want to merge,

     $ git checkout source_branch -- <paths>...
    Hint: It also works without `--` like seen in the linked post.
  • or to selectively merge hunks

     $ git checkout -p source_branch -- <paths>...

Alternatively, use reset and then add with the option -p,

    $ git reset <paths>...
    $ git add -p <paths>...
  • Finally commit

     $ git commit -m "'Merge' these changes"

What is the origin of foo and bar?


  • "Foo" and "bar" as metasyntactic variables were popularised by MIT and DEC, the first references are in work on LISP and PDP-1 and Project MAC from 1964 onwards.

  • Many of these people were in MIT's Tech Model Railroad Club, where we find the first documented use of "foo" in tech circles in 1959 (and a variant in 1958).

  • Both "foo" and "bar" (and even "baz") were well known in popular culture, especially from Smokey Stover and Pogo comics, which will have been read by many TMRC members.

  • Also, it seems likely the military FUBAR contributed to their popularity.

The use of lone "foo" as a nonsense word is pretty well documented in popular culture in the early 20th century, as is the military FUBAR. (Some background reading: FOLDOC FOLDOC Jargon File Jargon File Wikipedia RFC3092)

OK, so let's find some references.

STOP PRESS! After posting this answer, I discovered this perfect article about "foo" in the Friday 14th January 1938 edition of The Tech ("MIT's oldest and largest newspaper & the first newspaper published on the web"), Volume LVII. No. 57, Price Three Cents:

On Foo-ism

The Lounger thinks that this business of Foo-ism has been carried too far by its misguided proponents, and does hereby and forthwith take his stand against its abuse. It may be that there's no foo like an old foo, and we're it, but anyway, a foo and his money are some party. (Voice from the bleachers- "Don't be foo-lish!")

As an expletive, of course, "foo!" has a definite and probably irreplaceable position in our language, although we fear that the excessive use to which it is currently subjected may well result in its falling into an early (and, alas, a dark) oblivion. We say alas because proper use of the word may result in such happy incidents as the following.

It was an 8.50 Thermodynamics lecture by Professor Slater in Room 6-120. The professor, having covered the front side of the blackboard, set the handle that operates the lift mechanism, turning meanwhile to the class to continue his discussion. The front board slowly, majestically, lifted itself, revealing the board behind it, and on that board, writ large, the symbols that spelled "FOO"!

The Tech newspaper, a year earlier, the Letter to the Editor, September 1937:

By the time the train has reached the station the neophytes are so filled with the stories of the glory of Phi Omicron Omicron, usually referred to as Foo, that they are easy prey.


It is not that I mind having lost my first four sons to the Grand and Universal Brotherhood of Phi Omicron Omicron, but I do wish that my fifth son, my baby, should at least be warned in advance.

Hopefully yours,

Indignant Mother of Five.

And The Tech in December 1938:

General trend of thought might be best interpreted from the remarks made at the end of the ballots. One vote said, '"I don't think what I do is any of Pulver's business," while another merely added a curt "Foo."

The first documented "foo" in tech circles is probably 1959's Dictionary of the TMRC Language:

FOO: the sacred syllable (FOO MANI PADME HUM); to be spoken only when under inspiration to commune with the Deity. Our first obligation is to keep the Foo Counters turning.

These are explained at FOLDOC. The dictionary's compiler Pete Samson said in 2005:

Use of this word at TMRC antedates my coming there. A foo counter could simply have randomly flashing lights, or could be a real counter with an obscure input.

And from 1996's Jargon File 4.0.0:

Earlier versions of this lexicon derived 'baz' as a Stanford corruption of bar. However, Pete Samson (compiler of the TMRC lexicon) reports it was already current when he joined TMRC in 1958. He says "It came from "Pogo". Albert the Alligator, when vexed or outraged, would shout 'Bazz Fazz!' or 'Rowrbazzle!' The club layout was said to model the (mythical) New England counties of Rowrfolk and Bassex (Rowrbazzle mingled with (Norfolk/Suffolk/Middlesex/Essex)."

A year before the TMRC dictionary, 1958's MIT Voo Doo Gazette ("Humor suplement of the MIT Deans' office") (PDF) mentions Foocom, in "The Laws of Murphy and Finagle" by John Banzhaf (an electrical engineering student):

Further research under a joint Foocom and Anarcom grant expanded the law to be all embracing and universally applicable: If anything can go wrong, it will!

Also 1964's MIT Voo Doo (PDF) references the TMRC usage:

Yes! I want to be an instant success and snow customers. Send me a degree in: ...

  • Foo Counters

  • Foo Jung

Let's find "foo", "bar" and "foobar" published in code examples.

So, Jargon File 4.4.7 says of "foobar":

Probably originally propagated through DECsystem manuals by Digital Equipment Corporation (DEC) in 1960s and early 1970s; confirmed sightings there go back to 1972.

The first published reference I can find is from February 1964, but written in June 1963, The Programming Language LISP: its Operation and Applications by Information International, Inc., with many authors, but including Timothy P. Hart and Michael Levin:

Thus, since "FOO" is a name for itself, "COMITRIN" will treat both "FOO" and "(FOO)" in exactly the same way.

Also includes other metasyntactic variables such as: FOO CROCK GLITCH / POOT TOOR / ON YOU / SNAP CRACKLE POP / X Y Z

I expect this is much the same as this next reference of "foo" from MIT's Project MAC in January 1964's AIM-064, or LISP Exercises by Timothy P. Hart and Michael Levin:

car[((FOO . CROCK) . GLITCH)]


For both "foo" and "bar" together, the earliest reference I could find is from MIT's Project MAC in June 1966's AIM-098, or PDP-6 LISP by none other than Peter Samson:

EXPLODE, like PRIN1, inserts slashes, so (EXPLODE (QUOTE FOO/ BAR)) PRIN1's as (F O O // / B A R) or PRINC's as (F O O / B A R).

Some more recallations.

@Walter Mitty recalled on this site in 2008:

I second the jargon file regarding Foo Bar. I can trace it back at least to 1963, and PDP-1 serial number 2, which was on the second floor of Building 26 at MIT. Foo and Foo Bar were used there, and after 1964 at the PDP-6 room at project MAC.

John V. Everett recalls in 1996:

When I joined DEC in 1966, foobar was already being commonly used as a throw-away file name. I believe fubar became foobar because the PDP-6 supported six character names, although I always assumed the term migrated to DEC from MIT. There were many MIT types at DEC in those days, some of whom had worked with the 7090/7094 CTSS. Since the 709x was also a 36 bit machine, foobar may have been used as a common file name there.

Foo and bar were also commonly used as file extensions. Since the text editors of the day operated on an input file and produced an output file, it was common to edit from a .foo file to a .bar file, and back again.

It was also common to use foo to fill a buffer when editing with TECO. The text string to exactly fill one disk block was IFOO$HXA127GA$$. Almost all of the PDP-6/10 programmers I worked with used this same command string.

Daniel P. B. Smith in 1998:

Dick Gruen had a device in his dorm room, the usual assemblage of B-battery, resistors, capacitors, and NE-2 neon tubes, which he called a "foo counter." This would have been circa 1964 or so.

Robert Schuldenfrei in 1996:

The use of FOO and BAR as example variable names goes back at least to 1964 and the IBM 7070. This too may be older, but that is where I first saw it. This was in Assembler. What would be the FORTRAN integer equivalent? IFOO and IBAR?

Paul M. Wexelblat in 1992:

The earliest PDP-1 Assembler used two characters for symbols (18 bit machine) programmers always left a few words as patch space to fix problems. (Jump to patch space, do new code, jump back) That space conventionally was named FU: which stood for Fxxx Up, the place where you fixed Fxxx Ups. When spoken, it was known as FU space. Later Assemblers ( e.g. MIDAS allowed three char tags so FU became FOO, and as ALL PDP-1 programmers will tell you that was FOO space.

Bruce B. Reynolds in 1996:

On the IBM side of FOO(FU)BAR is the use of the BAR side as Base Address Register; in the middle 1970's CICS programmers had to worry out the various xxxBARs...I think one of those was FRACTBAR...

Here's a straight IBM "BAR" from 1955.

Other early references:

I haven't been able to find any references to foo bar as "inverted foo signal" as suggested in RFC3092 and elsewhere.

Here are a some of even earlier F00s but I think they're coincidences/false positives:

What is AndroidX?

androidx will replace support library after 28.0.0. You should migrate your project to use it. androidx uses Semantic Versioning. Using AndroidX will not be confused by version that is presented in library name and package name. Life becomes easier

[AndroidX and support compatibility]

Can I save input from form to .txt in HTML, using JAVASCRIPT/jQuery, and then use it?

Or this will work too the same way but without a save as choice:

<!DOCTYPE html>

<script type='text/javascript'>//<![CDATA[
(function () {
var textFile = null,
  makeTextFile = function (text) {
    var data = new Blob([text], {type: 'text/plain'});

    // If we are replacing a previously generated file we need to
    // manually revoke the object URL to avoid memory leaks.
    if (textFile !== null) {

    textFile = window.URL.createObjectURL(data);

    return textFile;

  var create = document.getElementById('create'),
    textbox = document.getElementById('textbox');

  create.addEventListener('click', function () {
    var link = document.getElementById('downloadlink');
    link.href = makeTextFile(textbox.value); = 'block';
  }, false);




  <textarea id="textbox">Type something here</textarea> <button id="create">Create file</button> <a download="info.txt" id="downloadlink" style="display: none">Download</a>

  // tell the embed parent frame the height of the content
  if (window.parent && window.parent.parent){
    window.parent.parent.postMessage(["resultsFrame", {
      height: document.body.getBoundingClientRect().height,
      slug: "qm5AG"
    }], "*")



Get first word of string

This code should get you the first word,

var str = "Hello m|sss sss|mmm ss"
//Now i separate them by "|"
var str1 = str.split('|');

 //Now i want to get the first word of every split-ed sting parts:

 for (var i=0;i<str1.length;i++)
     //What to do here to get the first word :(
     var words = str1[i].split(" ");

PostgreSQL: Resetting password of PostgreSQL on Ubuntu

Assuming you're the administrator of the machine, Ubuntu has granted you the right to sudo to run any command as any user.
Also assuming you did not restrict the rights in the pg_hba.conf file (in the /etc/postgresql/9.1/main directory), it should contain this line as the first rule:

# Database administrative login by Unix domain socket  
local   all             postgres                                peer

(About the file location: 9.1 is the major postgres version and main the name of your "cluster". It will differ if using a newer version of postgres or non-default names. Use the pg_lsclusters command to obtain this information for your version/system).

Anyway, if the pg_hba.conf file does not have that line, edit the file, add it, and reload the service with sudo service postgresql reload.

Then you should be able to log in with psql as the postgres superuser with this shell command:

sudo -u postgres psql

Once inside psql, issue the SQL command:

ALTER USER postgres PASSWORD 'newpassword';

In this command, postgres is the name of a superuser. If the user whose password is forgotten was ritesh, the command would be:

ALTER USER ritesh PASSWORD 'newpassword';

References: PostgreSQL 9.1.13 Documentation, Chapter 19. Client Authentication

Keep in mind that you need to type postgres with a single S at the end

If leaving the password in clear text in the history of commands or the server log is a problem, psql provides an interactive meta-command to avoid that, as an alternative to ALTER USER ... PASSWORD:

\password username

It asks for the password with a double blind input, then hashes it according to the password_encryption setting and issue the ALTER USER command to the server with the hashed version of the password, instead of the clear text version.

Retrieve data from website in android app

You can do the HTML parsing but it is not at all recommended instead ask the website owners to provide web services then you can parse that information.

Can I compile all .cpp files in src/ to .o's in obj/, then link to binary in ./?

Makefile part of the question

This is pretty easy, unless you don't need to generalize try something like the code below (but replace space indentation with tabs near g++)

SRC_DIR := .../src
OBJ_DIR := .../obj
SRC_FILES := $(wildcard $(SRC_DIR)/*.cpp)
OBJ_FILES := $(patsubst $(SRC_DIR)/%.cpp,$(OBJ_DIR)/%.o,$(SRC_FILES))
LDFLAGS := ...

main.exe: $(OBJ_FILES)
   g++ $(LDFLAGS) -o $@ $^

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp
   g++ $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<

Automatic dependency graph generation

A "must" feature for most make systems. With GCC in can be done in a single pass as a side effect of the compilation by adding -MMD flag to CXXFLAGS and -include $(OBJ_FILES:.o=.d) to the end of the makefile body:

-include $(OBJ_FILES:.o=.d)

And as guys mentioned already, always have GNU Make Manual around, it is very helpful.

how to wait for first command to finish?

Make sure that does something at the end what you can recognize (like touch /tmp/st_new.tmp when you remove the file first and always start one instance of
Then make a polling loop. First sleep the normal time you think you should wait, and wait short time in every loop. This will result in something like

sleep 10 # Minimum time for to finish
while [ ${retry} -lt ${max_retry} ]; do
   if [ -f /tmp/st_new.tmp ]; then
      break # call outside loop
      (( retry = retry + 1 ))
      sleep 1
if [ -f /tmp/st_new.tmp ]; then
   source ../../ 
   rm -f /tmp/st_new.tmp
   echo Something wrong with

Hive insert query like SQL

You can use below approach. With this, You don't need to create temp table OR txt/csv file for further select and load respectively.

INSERT INTO TABLE tablename SELECT value1,value2 FROM tempTable_with_atleast_one_records LIMIT 1.

Where tempTable_with_atleast_one_records is any table with atleast one record.

But problem with this approach is that If you have INSERT statement which inserts multiple rows like below one.

INSERT INTO yourTable values (1 , 'value1') , (2 , 'value2') , (3 , 'value3') ;

Then, You need to have separate INSERT hive statement for each rows. See below.

INSERT INTO TABLE yourTable SELECT 1 , 'value1' FROM tempTable_with_atleast_one_records LIMIT 1;
INSERT INTO TABLE yourTable SELECT 2 , 'value2' FROM tempTable_with_atleast_one_records LIMIT 1;
INSERT INTO TABLE yourTable SELECT 3 , 'value3' FROM tempTable_with_atleast_one_records LIMIT 1;

Python "SyntaxError: Non-ASCII character '\xe2' in file"

I had this exact issue running the simple .py code below:

import sys
print 'version is:', sys.version

DSM's code above provided the following:

1 'print \xe2\x80\x98version is\xe2\x80\x99, sys.version'

So the issue was that my text editor used SMART QUOTES, as John Y suggested. After changing the text editor settings and re-opening/saving the file, it works just fine.

How can I String.Format a TimeSpan object with a custom format in .NET?

Simple. Use TimeSpan.ToString with c, g or G. More information at MSDN

Ignore 'Security Warning' running script from command line

Try this, edit the file with:

notepad foo.ps1:Zone.Identifier

And set 'ZoneId=0'

docker: executable file not found in $PATH

In the error message shown:

Error response from daemon: Cannot start container foo_1: \
    exec: "grunt serve": executable file not found in $PATH

It is complaining that it cannot find the executable grunt serve, not that it could not find the executable grunt with the argument serve. The most likely explanation for that specific error is running the command with the json syntax:

[ "grunt serve" ]

in something like your compose file. That's invalid since the json syntax requires you to split up each parameter that would normally be split by the shell on each space for you. E.g.:

[ "grunt", "serve" ]

The other possible way you can get both of those into a single parameter is if you were to quote them into a single arg in your docker run command, e.g.

docker run your_image_name "grunt serve"

and in that case, you need to remove the quotes so it gets passed as separate args to the run command:

docker run your_image_name grunt serve

For others seeing this, the executable file not found means that Linux does not see the binary you are trying to run inside your container with the default $PATH value. That could mean lots of possible causes, here are a few:

  • Did you remember to include the binary inside your image? If you run a multi-stage image, make sure that binary install is run in the final stage. Run your image with an interactive shell and verify it exists:

    docker run -it --rm your_image_name /bin/sh
  • Your path when shelling into the container may be modified for the interactive shell, particularly if you use bash, so you may need to specify the full path to the binary inside the container, or you may need to update the path in your Dockerfile with:

    ENV PATH=$PATH:/custom/dir/bin
  • The binary may not have execute bits set on it, so you may need to make it executable. Do that with chmod:

    RUN chmod 755 /custom/dir/bin/executable
  • If you run the image with a volume, that volume can overlay the directory where the executable exists in your image. Volumes do not merge with the image, they get mounted in the filesystem tree same as any other Linux filesystem mount. That means files from the parent filesystem at the mount point are no longer visible. (Note that named volumes are initialized by docker from the image content, but this only happens when the named volume is empty.) So the fix is to not mount volumes on top of paths where you have executables you want to run from the image.

How can I install an older version of a package via NuGet?

Try the following:

Uninstall-Package Newtonsoft.Json -Force

Followed by:

Install-Package Newtonsoft.Json -Version <press tab key for autocomplete>

How do I make the text box bigger in HTML/CSS?

.textbox {
    height: 40px;

<div id=signin>  
    <input type="text" class="textbox" size="25%" height="50"/></br>
<input type="text" class="textbox" size="25%" height="50"/>

Make the font size larger and add height (or line height to the input boxes) I would not recommend adding those size and height attributes in the HTML as that can be handled by CSS. I have made a class text-box that can be used for multiple input boxes

oracle plsql: how to parse XML and insert into table

You can load an XML document into an XMLType, then query it, e.g.:

  x XMLType := XMLType(
    '<?xml version="1.0" ?> 
           <City>Los angeles</City>
           <City>Los angeles</City>
  FOR r IN (
    SELECT ExtractValue(Value(p),'/row/name/text()') as name
          ,ExtractValue(Value(p),'/row/Address/State/text()') as state
          ,ExtractValue(Value(p),'/row/Address/City/text()') as city
    FROM   TABLE(XMLSequence(Extract(x,'/person/row'))) p
    ) LOOP
    -- do whatever you want with, r.state,

insert vertical divider line between two nested divs, not full height

Can't think of a only css solution, but couldn't you just had a div between those 2 and set in the css the properties to look like a line like shown in the image? If you are using divs as they were table cells this is a pretty simple solution to the problem

How do we update URL or query strings using javascript/jQuery without reloading the page?

Yes and no. All the common web browsers has a security measure to prevent that. The goal is to prevent people from creating replicas of websites, change the URL to make it look correct, and then be able to trick people and get their info.

However, some HTML5 compatible web browsers has implemented an History API that can be used for something similar to what you want:

if (history.pushState) {
    var newurl = window.location.protocol + "//" + + window.location.pathname + '?myNewUrlQuery=1';

I tested, and it worked fine. It does not reload the page, but it only allows you to change the URL query. You would not be able to change the protocol or the host values.

For more information:

virtualbox Raw-mode is unavailable courtesy of Hyper-V windows 10

For me the combination of the following three was the solution:

1. control panel > turn windows features on or offf > Hyper-V : deselect

2. admin cmd > bcdedit > hypervisorlaunchtype:Auto disabling: bcdedit /set hypervisorlaunchtype off

3. gpedit.msc > 'Computer configuration > Administrative Template > System > Device Guard' > Turn On Virtualization Based Security : Change from 'Not configured' to 'Disabled'


note: after the reboot the VirtualBox worked, but Docker Desktop's VirtualBox started complaining about missing Hyper-V !

It seems that this might have been the root of all my evil... Extra info:

Java enum with multiple value types

First, the enum methods shouldn't be in all caps. They are methods just like other methods, with the same naming convention.

Second, what you are doing is not the best possible way to set up your enum. Instead of using an array of values for the values, you should use separate variables for each value. You can then implement the constructor like you would any other class.

Here's how you should do it with all the suggestions above:

public enum States {
    MASSACHUSETTS("Massachusetts",  "MA",   true),
    MICHIGAN     ("Michigan",       "MI",   false),
    ...; // all 50 of those

    private final String full;
    private final String abbr;
    private final boolean originalColony;

    private States(String full, String abbr, boolean originalColony) {
        this.full = full;
        this.abbr = abbr;
        this.originalColony = originalColony;

    public String getFullName() {
        return full;

    public String getAbbreviatedName() {
        return abbr;

    public boolean isOriginalColony(){
        return originalColony;

Not able to install Python packages [SSL: TLSV1_ALERT_PROTOCOL_VERSION]

I ran into this problem as well. The underlying problem is that the ssl library in Python 2.7 versions < 2.7.9 is no longer compatible with the pip mechanism.

If you are running on Windows, and you (like us) can't easily upgrade from an incompatible version of 2.7, FWIW, I found that if you copy the following files from another install of the latest version of Python (e.g. Python 2.7.15) on another machine to your installation:


it will effectively "upgrade" your SSL layer to one which is supported; we were then be able to use pip again, even to upgrade pip.

SQL query to make all data in a column UPPER CASE?


  MyColumn = UPPER(MyColumn)


  UPPER(MyColumn) AS MyColumn

How do I define a method which takes a lambda as a parameter in Java 8?

Basically to pass a lamda expression as a parameter, we need a type in which we can hold it. Just as an integer value we hold in primitive int or Integer class. Java doesn't have a separate type for lamda expression instead it uses an interface as the type to hold the argument. But that interface should be a functional interface.

Execute a command line binary with Node.js

You are looking for child_process.exec

Here is the example:

const exec = require('child_process').exec;
const child = exec('cat *.js bad_file | wc -l',
    (error, stdout, stderr) => {
        console.log(`stdout: ${stdout}`);
        console.log(`stderr: ${stderr}`);
        if (error !== null) {
            console.log(`exec error: ${error}`);

Git Pull vs Git Rebase

git pull and git rebase are not interchangeable, but they are closely connected.

git pull fetches the latest changes of the current branch from a remote and applies those changes to your local copy of the branch. Generally this is done by merging, i.e. the local changes are merged into the remote changes. So git pull is similar to git fetch & git merge.

Rebasing is an alternative to merging. Instead of creating a new commit that combines the two branches, it moves the commits of one of the branches on top of the other.

You can pull using rebase instead of merge (git pull --rebase). The local changes you made will be rebased on top of the remote changes, instead of being merged with the remote changes.

Atlassian has some excellent documentation on merging vs. rebasing.

How to create an ArrayList from an Array in PowerShell?

I can't get that constructor to work either. This however seems to work:

# $temp = Get-ResourceFiles
$resourceFiles = New-Object System.Collections.ArrayList($null)

You can also pass an integer in the constructor to set an initial capacity.

What do you mean when you say you want to enumerate the files? Why can't you just filter the wanted values into a fresh array?


It seems that you can use the array constructor like this:

$resourceFiles = New-Object System.Collections.ArrayList(,$someArray)

Note the comma. I believe what is happening is that when you call a .NET method, you always pass parameters as an array. PowerShell unpacks that array and passes it to the method as separate parameters. In this case, we don't want PowerShell to unpack the array; we want to pass the array as a single unit. Now, the comma operator creates arrays. So PowerShell unpacks the array, then we create the array again with the comma operator. I think that is what is going on.

java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.testing.models.Account

The way I could mitigate the JSON Array to collection of LinkedHashMap objects problem was by using CollectionType rather than a TypeReference . This is what I did and worked:

public <T> List<T> jsonArrayToObjectList(String json, Class<T> tClass) throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    CollectionType listType = mapper.getTypeFactory().constructCollectionType(ArrayList.class, tClass);
    List<T> ts = mapper.readValue(json, listType);
    LOGGER.debug("class name: {}", ts.get(0).getClass().getName());
    return ts;

Using the TypeReference, I was still getting an ArrayList of LinkedHashMaps, i.e. does not work:

public <T> List<T> jsonArrayToObjectList(String json, Class<T> tClass) throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    List<T> ts = mapper.readValue(json, new TypeReference<List<T>>(){});
    LOGGER.debug("class name: {}", ts.get(0).getClass().getName());
    return ts;

Create intermediate folders if one doesn't exist

You have to actually call some method to create the directories. Just creating a file object will not create the corresponding file or directory on the file system.

You can use File#mkdirs() method to create the directory: -


Difference between File#mkdir() and File#mkdirs() is that, the later will create any intermediate directory if it does not exist.

WPF Button with Image

You want to do something like this instead:

        <Image Source="Pictures/apple.jpg" />
        <TextBlock>Disconnect from Server</TextBlock>

JPA Native Query select and cast object

You might want to try one of the following ways:

  • Using the method createNativeQuery(sqlString, resultClass)

    Native queries can also be defined dynamically using the EntityManager.createNativeQuery() API.

    String sql = "SELECT USER.* FROM USER_ AS USER WHERE ID = ?";
    Query query = em.createNativeQuery(sql, User.class);
    query.setParameter(1, id);
    User user = (User) query.getSingleResult();
  • Using the annotation @NamedNativeQuery

    Native queries are defined through the @NamedNativeQuery and @NamedNativeQueries annotations, or <named-native-query> XML element.

        query="SELECT USER.* FROM USER_ AS USER WHERE ID = ?",
    public class User { ... }
    Query query = em.createNamedQuery("complexQuery", User.class);
    query.setParameter(1, id);
    User user = (User) query.getSingleResult();

You can read more in the excellent open book Java Persistence (available in PDF).

NOTE: With regard to use of getSingleResult(), see Why you should never use getSingleResult() in JPA.

How to iterate object keys using *ngFor

If you are using a map() operator on your response,you could maybe chain a toArray() operator to it...then you should be able to iterate through newly created least that worked for me :)

How to edit an Android app?

Generally speaking, a software product isn't your "property already", as you said in the comment. Most of the times (I won't be irresponsible to say anything in open), it's licensed to you. A license to use some thing is not the same thing as owning (property rights) that very same thing.

That's because there are authorship, copyright, intellectual property rights applicable to it. I don't know how things work in United States (or in your country), but it's generally accepted that the work of a mind, a creative work, must not be changed in its nature as such to make the expression of art to be different than that expression that the author intended. That applies for example, in some cases, to architectural work (in most countries, you can't change the appearance of a building to "desfigure" the work of art of the architect, without his prior consent). Exceptions are made, obviously, when the author expressly authorizes such changes (e.g., Creative Commons licenses, open source licenses etc.).

Anyway, that's why you see in most EULAs the typical sentence: "this software is licensed, not sold". That's the purpose and reason why.

Now that you understand the reasons why you can't wander around changing other people's art, let me be technical.

There are possible ways to decompile Java programs. You can use dex2jar, it provides a somewhat good start for you to start looking for things and changes. And perhaps rebuild the code by mounting back the pieces together. Good luck, as most people obfuscate their codes to make that harder.

However, let me say that it's still forbidden to change programs, as I said above. And it's extremely unethical. It makes me sad that people do that with no scruples (not saying it's your case, just warning you). It shouldn't need people to be at the other side to understand that. Or maybe that's just me, who lives in a country where piracy is rampant.

The tools are always out there. But the conscience, unfortunately, not always.

edit: in case it isn't clear enough already, I do NOT approve the use of these programs. I use them myself to check how hard my own applications are to be reverse engineered. But I also think that explaning is always better than denial (better be here).

How to check if running as root in a bash script

In this answer, let it be clear, I presume the reader is able to read bash and POSIX shell scripts like dash.

I believe there is not much to explain here since the highly voted answers do a good job of explaining much of it.

Yet, if there is anything to explain further, don't hesitate to comment, I will do my best filling the gaps.

Optimized all-round solution for performance and reliability; all shells compatible

New solution:

# bool function to test if the user is root or not
is_user_root () { [ ${EUID:-$(id -u)} -eq 0 ]; }

Benchmark (save to file is_user_root__benchmark)

#|                           is_user_root() benchmark                           |
#|                  "Bash is fast while Dash is slow in this"                   |
#|                          Language: POSIX shell script                        |
#|                        Copyright: 2020 Vlastimil Burian                      |
#|                      M@il: info[..]vlastimilburian[..]cz                     |
#|                               License: GPL 3.0                               |
#|                                 Version: 1.1                                 |

readonly iterations=10000

# intentionally, the file does not have executable bit, nor it has no shebang
# to use it, just call the file directly with your shell interpreter like:

# bash is_user_root__benchmark
# dash is_user_root__benchmark

is_user_root () { [ ${EUID:-$(id -u)} -eq 0 ]; }

print_time   () { date +"%T.%2N"; }
print_start  () { printf '%s' 'Start  : '; print_time; }
print_finish () { printf '%s' 'Finish : '; print_time; }

printf '%s\n' '___is_user_root()___'; print_start
i=1; while [ $i -lt $iterations ]; do
    i=$((i + 1))
done; print_finish

Examples of use and duration:

$ dash is_user_root__benchmark 
Start  : 03:14:04.81
Finish : 03:14:13.29

$ bash is_user_root__benchmark 
Start  : 03:16:22.90
Finish : 03:16:23.08


Since it is multitude times faster to read the $EUID standard bash variable, the effective user ID number, than executing id -u command to POSIX-ly find the user ID, this solution combines both into a nicely packed function. If, and only if, the $EUID is for any reason not available, the id -u command will get executed, ensuring we get the proper return value no matter the circumstances.

Why I post this solution after so many years the OP has asked

Well, if I see correctly, there does seem to be a missing piece of code above.

You see, there are many variables which have to be taken into account, and one of them is combining performance and reliability.

Portable POSIX solution + Example of usage of the above function


# bool function to test if the user is root or not (POSIX only)
is_user_root() { [ "$(id -u)" -eq 0 ]; }

if is_user_root; then
    echo 'You are the almighty root!'
    exit 0 # implicit, here it serves the purpose to be explicit for the reader
    echo 'You are just an ordinary user.' >&2
    exit 1


As much as you possibly don't like it, the Unix / Linux environment has diversified a lot. Meaning there are people who like bash so much, they don't even think of portability (POSIX shells). Others like me prefer the POSIX shells. It is nowadays a matter of personal choice and needs.

Printing out all the objects in array list

Override toString() method in Student class as below:

   public String toString() {
        return ("StudentName:"+this.getStudentName()+
                    " Student No: "+ this.getStudentNo() +
                    " Email: "+ this.getEmail() +
                    " Year : " + this.getYear());

Get the current script file name


I've found it much simpler to use $argv[0]. The name of the executing script is always the first element in the $argv array. Unlike all other methods suggested in other answers, this method does not require the use of basename() to remove the directory tree. For example:

  • echo __FILE__; returns something like /my/directory/path/my_script.php

  • echo $argv[0]; returns my_script.php

Resolving tree conflict

Basically, tree conflicts arise if there is some restructure in the folder structure on the branch. You need to delete the conflict folder and use svn clean once. Hope this solves your conflict.