Programs & Examples On #Pax runner

Pax Runner is a tool to provision OSGi bundles in all major open source OSGi framework implementations (Felix, Equinox, Knopflerfish, Concierge).

String delimiter in string.split method

Split uses regex, and the pipe char | has special meaning in regex, so you need to escape it. There are a few ways to do this, but here's the simplest:

String[] tokens = line.split("\\|\\|");

Best practice when adding whitespace in JSX

You can use curly braces like expression with both double quotes and single quotes for space i.e.,

{" "} or {' '}

You can also use ES6 template literals i.e.,

`   <li></li>` or `  ${value}`

You can also use &nbsp like below (inside span)

<span>sample text &nbsp; </span>

You can also use &nbsp in dangerouslySetInnerHTML when printing html content

<div dangerouslySetInnerHTML={{__html: 'sample html text: &nbsp;'}} />

Could you explain STA and MTA?

Code that calls COM object dlls (for example, to read proprietary data files), may work fine in a user interface but hang mysteriously from a service. The reason is that as of .Net 2.0 user interfaces assume STA (thread-safe) while services assume MTA ((before that, services assumed STA). Having to create an STA thread for every COM call in a service can add significant overhead.

Replace "\\" with "\" in a string in C#

You can simply do a replace in your string like


How to include CSS file in Symfony 2 and Twig?

You are doing everything right, except passing your bundle path to asset() function.

According to documentation - in your example this should look like below:

{{ asset('bundles/webshome/css/main.css') }}

Tip: you also can call assets:install with --symlink key, so it will create symlinks in web folder. This is extremely useful when you often apply js or css changes (in this way your changes, applied to src/YouBundle/Resources/public will be immediately reflected in web folder without need to call assets:install again):

app/console assets:install web --symlink

Also, if you wish to add some assets in your child template, you could call parent() method for the Twig block. In your case it would be like this:

{% block stylesheets %}
    {{ parent() }}

    <link href="{{ asset('bundles/webshome/css/main.css') }}" rel="stylesheet">
{% endblock %}

How to replace string in Groovy

You need to escape the backslash \:

println yourString.replace("\\", "/")

How to save a data frame as CSV to a user selected location using tcltk

Take a look at the write.csv or the write.table functions. You just have to supply the file name the user selects to the file parameter, and the dataframe to the x parameter:

write.csv(x=df, file="myFileName")

Update multiple tables in SQL Server using INNER JOIN

You can't update more that one table in a single statement, however the error message you get is because of the aliases, you could try this :


update A
from table1 A inner join table2 B
and A.ORG_ID = @ORG_ID

update B
from table2 B inner join table1 A
    on B.ORG_ID = A.ORG_ID
    and A.ORG_ID = @ORG_ID


How do I run a program from command prompt as a different user and as an admin

See here:

According to that the command looks like this for admin:

 runas /noprofile /user:Administrator cmd

How do I select the parent form based on which submit button is clicked?

i used the following method & it worked fine for me


$('#mybutton').closest("form") did the trick for me.

What is the meaning of the CascadeType.ALL for a @ManyToOne JPA association

See here for an example from the OpenJPA docs. CascadeType.ALL means it will do all actions.


CascadeType.PERSIST: When persisting an entity, also persist the entities held in its fields. We suggest a liberal application of this cascade rule, because if the EntityManager finds a field that references a new entity during the flush, and the field does not use CascadeType.PERSIST, it is an error.

CascadeType.REMOVE: When deleting an entity, it also deletes the entities held in this field.

CascadeType.REFRESH: When refreshing an entity, also refresh the entities held in this field.

CascadeType.MERGE: When merging entity state, also merge the entities held in this field.


How do I join two lines in vi?

If you want to join the selected lines (you are in visual mode), then just press gJ to join your lines with no spaces whatsoever.

This is described in greater detail on the vi/Vim Stack Exchange site.

Converting Decimal to Binary Java

 * converting decimal to binary
 * @param n the number
private static void toBinary(int n) {
    if (n == 0) {
        return; //end of recursion
    } else {
        toBinary(n / 2);
        System.out.print(n % 2);

 * converting decimal to binary string
 * @param n the number
 * @return the binary string of n
private static String toBinaryString(int n) {
    Stack<Integer> bits = new Stack<>();
    do {
        bits.push(n % 2);
        n /= 2;
    } while (n != 0);

    StringBuilder builder = new StringBuilder();
    while (!bits.isEmpty()) {
    return builder.toString();

Or you can use Integer.toString(int i, int radix)

e.g:(Convert 12 to binary)

Integer.toString(12, 2)

How to cast from List<Double> to double[] in Java?

As per your question,

List<Double> frameList =  new ArrayList<Double>();
  1. First you have to convert List<Double> to Double[] by using

    Double[] array = frameList.toArray(new Double[frameList.size()]);
  2. Next you can convert Double[] to double[] using

    double[] doubleArray = ArrayUtils.toPrimitive(array);

You can directly use it in one line:

double[] array = ArrayUtils.toPrimitive(frameList.toArray(new Double[frameList.size()]));

Android: Clear Activity Stack

Most of you are wrong. If you want to close existing activity stack regardless of what's in there and create new root, correct set of flags is the following:


From the doc:

public static final int FLAG_ACTIVITY_CLEAR_TASK
Added in API level 11

If set in an Intent passed to Context.startActivity(), this flag will cause any existing task that would be associated with the activity to be cleared before the activity is started. That is, the activity becomes the new root of an otherwise empty task, and any old activities are finished. This can only be used in conjunction with FLAG_ACTIVITY_NEW_TASK.

What is a quick way to force CRLF in C# / .NET?


A string containing "\r\n" for non-Unix platforms, or a string containing "\n" for Unix platforms.

How can you test if an object has a specific property?

You can use Get-Member

if(Get-Member -inputobject $var -name "Property" -Membertype Properties){
#Property exists

Twitter Bootstrap add active class to li

For Bootstrap 3:

var url = window.location;
// Will only work if string in href matches with location
$('ul.nav a[href="'+ url +'"]').parent().addClass('active');

// Will also work for relative and absolute hrefs
$('ul.nav a').filter(function() {
    return this.href == url;


For Bootstrap 4:

var url = window.location;
// Will only work if string in href matches with location
$('ul.navbar-nav a[href="'+ url +'"]').parent().addClass('active');

// Will also work for relative and absolute hrefs
$('ul.navbar-nav a').filter(function() {
    return this.href == url;

How do I install g++ on MacOS X?

That's the compiler that comes with Apple's XCode tools package. They've hacked on it a little, but basically it's just g++.

You can download XCode for free (well, mostly, you do have to sign up to become an ADC member, but that's free too) here:

Edit 2013-01-25: This answer was correct in 2010. It needs an update.

While XCode tools still has a command-line C++ compiler, In recent versions of OS X (I think 10.7 and later) have switched to clang/llvm (mostly because Apple wants all the benefits of Open Source without having to contribute back and clang is BSD licensed). Secondly, I think all you have to do to install XCode is to download it from the App store. I'm pretty sure it's free there.

So, in order to get g++ you'll have to use something like homebrew (seemingly the current way to install Open Source software on the Mac (though homebrew has a lot of caveats surrounding installing gcc using it)), fink (basically Debian's apt system for OS X/Darwin), or MacPorts (Basically, OpenBSDs ports system for OS X/Darwin) to get it.

Fink definitely has the right packages. On 2016-12-26, it had gcc 5 and gcc 6 packages.

I'm less familiar with how MacPorts works, though some initial cursory investigation indicates they have the relevant packages as well.


Actually, it will takes 101 bytes.

MySQL Reference

What are the retransmission rules for TCP?

There's no fixed time for retransmission. Simple implementations estimate the RTT (round-trip-time) and if no ACK to send data has been received in 2x that time then they re-send.

They then double the wait-time and re-send once more if again there is no reply. Rinse. Repeat.

More sophisticated systems make better estimates of how long it should take for the ACK as well as guesses about exactly which data has been lost.

The bottom-line is that there is no hard-and-fast rule about exactly when to retransmit. It's up to the implementation. All retransmissions are triggered solely by the sender based on lack of response from the receiver.

TCP never drops data so no, there is no way to indicate a server should forget about some segment.

How to get user's high resolution profile picture on Twitter?

use this URL : ""

If you are using TWitter SDK you can get the user name when logged in, with TWTRAPIClient, using TWTRAuthSession.

This is the code snipe for iOS:

if let twitterId = session.userID{
   let twitterClient = TWTRAPIClient(userID: twitterId)
   twitterClient.loadUser(withID: twitterId) {(user, error) in
       if let userName = user?.screenName{
          let url = "\(userName)/profile_image?size=original")

Delete empty lines using sed

sed '/^$/d' should be fine, are you expecting to modify the file in place? If so you should use the -i flag.

Maybe those lines are not empty, so if that's the case, look at this question Remove empty lines from txtfiles, remove spaces from start and end of line I believe that's what you're trying to achieve.

Share link on Google+

No, you cannot. Google Plus has been discontinued. Clicking any link for any answer here brings me to this text:

Google+ is no longer available for consumer (personal) and brand accounts

From all of us on the Google+ team,

thank you for making Google+ such a special place.

There is one section that reads that the product is continued for "G Suite," but as of Feb., 2020, the chat and social service listed for G Suite is Hangouts, not Google+.

The format was documented at, but this documentation has since been removed, probably because no part of Google+ continues in development. If you are feeling nostalgic, you can see what the API used to say with an link.

Code line wrapping - how to handle long lines

I think that moving last operator to the beginning of the next line is a good practice. That way you know right away the purpose of the second line, even it doesn't start with an operator. I also recommend 2 indentation spaces (2 tabs) for a previously broken tab, to differ it from the normal indentation. That is immediately visible as continuing previous line. Therefore I suggest this:

private static final Map<Class<? extends Persistent>, PersistentHelper> class2helper 
            = new HashMap<Class<? extends Persistent>, PersistentHelper>();

JOIN queries vs multiple queries

This question is old, but is missing some benchmarks. I benchmarked JOIN against its 2 competitors:

  • N+1 queries
  • 2 queries, the second one using a WHERE IN(...) or equivalent

The result is clear: on MySQL, JOIN is much faster. N+1 queries can drop the performance of an application drastically:


That is, unless you select a lot of records that point to a very small number of distinct, foreign records. Here is a benchmark for the extreme case:

JOIN vs N+1 - all records pointing to the same foreign record

This is very unlikely to happen in a typical application, unless you're joining a -to-many relationship, in which case the foreign key is on the other table, and you're duplicating the main table data many times.


  • For *-to-one relationships, always use JOIN
  • For *-to-many relationships, a second query might be faster

See my article on Medium for more information.

PostgreSQL naming conventions

There isn't really a formal manual, because there's no single style or standard.

So long as you understand the rules of identifier naming you can use whatever you like.

In practice, I find it easier to use lower_case_underscore_separated_identifiers because it isn't necessary to "Double Quote" them everywhere to preserve case, spaces, etc.

If you wanted to name your tables and functions "@MyA??! ""betty"" Shard$42" you'd be free to do that, though it'd be pain to type everywhere.

The main things to understand are:

  • Unless double-quoted, identifiers are case-folded to lower-case, so MyTable, MYTABLE and mytable are all the same thing, but "MYTABLE" and "MyTable" are different;

  • Unless double-quoted:

    SQL identifiers and key words must begin with a letter (a-z, but also letters with diacritical marks and non-Latin letters) or an underscore (_). Subsequent characters in an identifier or key word can be letters, underscores, digits (0-9), or dollar signs ($).

  • You must double-quote keywords if you wish to use them as identifiers.

In practice I strongly recommend that you do not use keywords as identifiers. At least avoid reserved words. Just because you can name a table "with" doesn't mean you should.

What does ON [PRIMARY] mean?

To add a very important note on what Mark S. has mentioned in his post. In the specific SQL Script that has been mentioned in the question you can NEVER mention two different file groups for storing your data rows and the index data structure.

The reason why is due to the fact that the index being created in this case is a clustered Index on your primary key column. The clustered index data and the data rows of your table can NEVER be on different file groups.

So in case you have two file groups on your database e.g. PRIMARY and SECONDARY then below mentioned script will store your row data and clustered index data both on PRIMARY file group itself even though I've mentioned a different file group ([SECONDARY]) for the table data. More interestingly the script runs successfully as well (when I was expecting it to give an error as I had given two different file groups :P). SQL Server does the trick behind the scene silently and smartly.

CREATE TABLE [dbo].[be_Categories](
    [CategoryID] [uniqueidentifier] ROWGUIDCOL  NOT NULL CONSTRAINT [DF_be_Categories_CategoryID]  DEFAULT (newid()),
    [CategoryName] [nvarchar](50) NULL,
    [Description] [nvarchar](200) NULL,
    [ParentID] [uniqueidentifier] NULL,
    [CategoryID] ASC

NOTE: Your index can reside on a different file group ONLY if the index being created is non-clustered in nature.

The below script which creates a non-clustered index will get created on [SECONDARY] file group instead when the table data already resides on [PRIMARY] file group:

CREATE NONCLUSTERED INDEX [IX_Categories] ON [dbo].[be_Categories]
    [CategoryName] ASC

You can get more information on how storing non-clustered indexes on a different file group can help your queries perform better. Here is one such link.

What's the best way to store co-ordinates (longitude/latitude, from Google Maps) in SQL Server?

Store both as float, and use unique key words on them.i.em

create table coordinates(
coord_uid counter primary key,
latitude float,
longitude float,
constraint la_long unique(latitude, longitude)

CKEditor instance already exists

I had the same problem where I was receiving a null reference exception and the word "null" would be displayed in the editor. I tried a handful of solutions, including upgrading the editor to 3.4.1 to no avail.

I ended up having to edit the source. At about line 416 to 426 in _source\plugins\wysiwygarea\plugin.js, there's a snippet like this:

iframe = CKEDITOR.dom.element.createFromHtml( '&lt;iframe' + ... + '></iframe>' );

In FF at least, the iframe isn't completely instantiated by the time it's needed. I surrounded the rest of the function after that line with a setTimeout function:

iframe = CKEDITOR.dom.element.createFromHtml( '<iframe' + ... + '></iframe>' );
    // Running inside of Firefox chrome the load event doesn't bubble like in a normal page (#5689)
}, 1000);


// The script that launches the bootstrap logic on 'domReady', so the document

The text renders consistently now in the modal dialogs.

HTML list-style-type dash

Here is my fiddle version:

The (modernizr) class .generatedcontent on <html> practically means IE8+ and every other sane browser.

<html class="generatedcontent">
  <ul class="ul-dash hanging">
    <li>Lorem ipsum dolor sit amet stack o verflow dot com</li>
    <li>Lorem ipsum dolor sit amet stack o verflow dot com</li>


.ul-dash {
  margin: 0;

.ul-dash {
  margin-left: 0em;
  padding-left: 1.5em;

.ul-dash.hanging > li { /* remove '>' for IE6 support */
  padding-left: 1em;
  text-indent: -1em;

.generatedcontent .ul-dash {
  list-style: none;
.generatedcontent .ul-dash > li:before {
  content: "–";
  text-indent: 0;
  display: inline-block;
  width: 0;
  position: relative;
  left: -1.5em;

g++ undefined reference to typeinfo

I encounter an situation that is rare, but this may help other friends in similar situation. I have to work on an older system with gcc 4.4.7. I have to compile code with c++11 or above support, so I build the latest version of gcc 5.3.0. When building my code and linking to the dependencies if the dependency is build with older compiler, then I got 'undefined reference to' error even though I clearly defined the linking path with -L/path/to/lib -llibname. Some packages such as boost and projects build with cmake usually has a tendency to use the older compiler, and they usually cause such problems. You have to go a long way to make sure they use the newer compiler.

CSS: Auto resize div to fit container width

I have updated your jsfiddle and here is CSS changes you need to do:

    margin-right: -210px;

How can I prevent the TypeError: list indices must be integers, not tuple when copying a python list to a numpy array?

import numpy as np

mean_data = np.array([
[6.0, 315.0, 4.8123788544375692e-06],
[6.5, 0.0, 2.259217450023793e-06],
[6.5, 45.0, 9.2823565008402673e-06],
[6.5, 90.0, 8.309270169336028e-06],
[6.5, 135.0, 6.4709418114245381e-05],
[6.5, 180.0, 1.7227922423558414e-05],
[6.5, 225.0, 1.2308522579848724e-05],
[6.5, 270.0, 2.6905672894824344e-05],
[6.5, 315.0, 2.2727114437176048e-05]])

R = mean_data[:,0]
print R
print R.shape


The reason why you had an invalid index error is the lack of a comma between mean_data and the values you wanted to add.

Also, np.append returns a copy of the array, and does not change the original array. From the documentation :

Returns : append : ndarray

A copy of arr with values appended to axis. Note that append does not occur in-place: a new array is allocated and filled. If axis is None, out is a flattened array.

So you have to assign the np.append result to an array (could be mean_data itself, I think), and, since you don't want a flattened array, you must also specify the axis on which you want to append.

With that in mind, I think you could try something like

mean_data = np.append(mean_data, [[ur, ua, np.mean(data[samepoints,-1])]], axis=0)

Do have a look at the doubled [[ and ]] : I think they are necessary since both arrays must have the same shape.

How to get the background color code of an element in hex?

function getBackgroundColor($dom) {
    var bgColor = "";
    while ($dom[0].tagName.toLowerCase() != "html") {
      bgColor = $dom.css("background-color");
      if (bgColor != "rgba(0, 0, 0, 0)" && bgColor != "transparent") {
      $dom = $dom.parent();
    return bgColor;

working properly under Chrome and Firefox

NameError: uninitialized constant (rails)

I started having this issue after upgrading from Rails 5.1 to 5.2
It got solved with:

spring stop
spring binstub --all
spring start
rails s

Make sure that the controller has a parameterless public constructor error

I've got this error when I accidentally defined a property as a specific object type, instead of the interface type I have defined in UnityContainer.

For example:

Defining UnityContainer:

var container = new UnityContainer();
container.RegisterInstance(typeof(IDashboardRepository), DashboardRepository);
config.DependencyResolver = new UnityResolver(container);

SiteController (the wrong way - notice repo type):

private readonly DashboardRepository _repo;

public SiteController(DashboardRepository repo)
    _repo = repo;

SiteController (the right way):

private readonly IDashboardRepository _repo;

public SiteController(IDashboardRepository repo)
    _repo = repo;

copy db file with adb pull results in 'permission denied' error

This is a bit late, but installing adbd Insecure worked for me. It makes adb run in root mode on production ("secure") devices, which is what you likely have.

A paid version is also available on Google Play if you want to support the developer.

How to create virtual column using MySQL SELECT?

Your syntax would create an alias for a as b, but it wouldn't have scope beyond the results of the statement. It sounds like you may want to create a VIEW

vuejs update parent data from child component

From the documentation:

In Vue.js, the parent-child component relationship can be summarized as props down, events up. The parent passes data down to the child via props, and the child sends messages to the parent via events. Let’s see how they work next.

enter image description here

How to pass props

Following is the code to pass props to a child element:

  <input v-model="parentMsg">
  <child v-bind:my-message="parentMsg"></child>

How to emit event


<div id="counter-event-example">
  <p>{{ total }}</p>
  <button-counter v-on:increment="incrementTotal"></button-counter>
  <button-counter v-on:increment="incrementTotal"></button-counter>


Vue.component('button-counter', {
  template: '<button v-on:click="increment">{{ counter }}</button>',
  data: function () {
    return {
      counter: 0
  methods: {
    increment: function () {
      this.counter += 1
new Vue({
  el: '#counter-event-example',
  data: {
    total: 0
  methods: {
    incrementTotal: function () { += 1

onClick function of an input type="button" not working

When I try:

<input type="button" id="moreFields" onclick="alert('The text will be show!!'); return false;" value="Give me more fields!"  />

It's worked well. So I think the problem is position of moreFields() function. Ensure that function will be define before your input tag.

Pls try:

<script type="text/javascript">
    function moreFields() {
        alert("The text will be show");

<input type="button" id="moreFields" onclick="moreFields()" value="Give me more fields!"  />

Hope it helped.

how to get request path with express req object

//auth required or redirect
app.use('/account', function(req, res, next) {
  if ( !req.session.user ) {
  } else {

req.path is / when it should be /account ??

The reason for this is that Express subtracts the path your handler function is mounted on, which is '/account' in this case.

Why do they do this?

Because it makes it easier to reuse the handler function. You can make a handler function that does different things for req.path === '/' and req.path === '/goodbye' for example:

function sendGreeting(req, res, next) {
  res.send(req.path == '/goodbye' ? 'Farewell!' : 'Hello there!')

Then you can mount it to multiple endpoints:

app.use('/world', sendGreeting)
app.use('/aliens', sendGreeting)


/world           ==>  Hello there!
/world/goodbye   ==>  Farewell!
/aliens          ==>  Hello there!
/aliens/goodbye  ==>  Farewell!

Why does JSHint throw a warning if I am using const?

If you're using VSCode:


  • Go to preferences -> settings (cmd + ,)
  • Type jshint.options into the search bar
  • Hover over it and click on the pencil icon
  • Its now appended on the right side.
  • Add "esversion": 6 to the options object.


Or simply add this to your user settings:

"jshint.options": {
    "esversion": 6

[UPDATE] new vscode settings

  • Go to preferences -> settings (cmd + ,)
  • type jshint into search

VSCode Settings

  • continue with step 2.

Make error: missing separator

In my case, I was actually missing a tab in between ifeq and the command on the next line. No spaces were there to begin with.

ifeq ($(wildcard $DIR_FILE), )
cd $FOLDER; cp -f $DIR_FILE.tpl $DIR_FILE.xs;

Should have been:

ifeq ($(wildcard $DIR_FILE), )
<tab>cd $FOLDER; cp -f $DIR_FILE.tpl $DIR_FILE.xs;

Note the <tab> is an actual tab character

Overlaying histograms with ggplot2 in R

While only a few lines are required to plot multiple/overlapping histograms in ggplot2, the results are't always satisfactory. There needs to be proper use of borders and coloring to ensure the eye can differentiate between histograms.

The following functions balance border colors, opacities, and superimposed density plots to enable the viewer to differentiate among distributions.

Single histogram:

plot_histogram <- function(df, feature) {
    plt <- ggplot(df, aes(x=eval(parse(text=feature)))) +
    geom_histogram(aes(y = ..density..), alpha=0.7, fill="#33AADE", color="black") +
    geom_density(alpha=0.3, fill="red") +
    geom_vline(aes(xintercept=mean(eval(parse(text=feature)))), color="black", linetype="dashed", size=1) +
    labs(x=feature, y = "Density")

Multiple histogram:

plot_multi_histogram <- function(df, feature, label_column) {
    plt <- ggplot(df, aes(x=eval(parse(text=feature)), fill=eval(parse(text=label_column)))) +
    geom_histogram(alpha=0.7, position="identity", aes(y = ..density..), color="black") +
    geom_density(alpha=0.7) +
    geom_vline(aes(xintercept=mean(eval(parse(text=feature)))), color="black", linetype="dashed", size=1) +
    labs(x=feature, y = "Density")
    plt + guides(fill=guide_legend(title=label_column))


Simply pass your data frame into the above functions along with desired arguments:

plot_histogram(iris, 'Sepal.Width')

enter image description here

plot_multi_histogram(iris, 'Sepal.Width', 'Species')

enter image description here

The extra parameter in plot_multi_histogram is the name of the column containing the category labels.

We can see this more dramatically by creating a dataframe with many different distribution means:

a <-data.frame(n=rnorm(1000, mean = 1), category=rep('A', 1000))
b <-data.frame(n=rnorm(1000, mean = 2), category=rep('B', 1000))
c <-data.frame(n=rnorm(1000, mean = 3), category=rep('C', 1000))
d <-data.frame(n=rnorm(1000, mean = 4), category=rep('D', 1000))
e <-data.frame(n=rnorm(1000, mean = 5), category=rep('E', 1000))
f <-data.frame(n=rnorm(1000, mean = 6), category=rep('F', 1000))
many_distros <-'rbind', list(a,b,c,d,e,f))

Passing data frame in as before (and widening chart using options):

options(repr.plot.width = 20, repr.plot.height = 8)
plot_multi_histogram(many_distros, 'n', 'category')

enter image description here

iPhone SDK:How do you play video inside a view? Rather than fullscreen

Use the following method.

self.imageView_VedioContainer is the container view of your AVPlayer.

- (void)playMedia:(UITapGestureRecognizer *)tapGesture
    playerViewController = [[AVPlayerViewController alloc] init];

    playerViewController.player = [AVPlayer playerWithURL:[[NSBundle mainBundle]
    [playerViewController.player play];
    playerViewController.showsPlaybackControls =YES;
    [playerViewController.view setAutoresizingMask:UIViewAutoresizingNone];// you can comment this line 
    [self.imageView_VedioContainer addSubview: playerViewController.view];

How to change color of Toolbar back button in Android?

For white Toolbar Title and White Up arrow, use following theme:


What difference does .AsNoTracking() make?

The difference is that in the first case the retrieved user is not tracked by the context so when you are going to save the user back to database you must attach it and set correctly state of the user so that EF knows that it should update existing user instead of inserting a new one. In the second case you don't need to do that if you load and save the user with the same context instance because the tracking mechanism handles that for you.

Can I force a UITableView to hide the separator between empty cells?

If you use iOS 7 SDK, this is very simple.

Just add this line in your viewDidLoad method:

self.yourTableView.tableFooterView = [[UIView alloc] initWithFrame:CGRectZero];

install apt-get on linux Red Hat server

If you insist on using yum, try yum install apt. As read on this site: Link

Error "Metadata file '...\Release\project.dll' could not be found in Visual Studio"

In my case, I had some errors in my code. Visual Studio showed the error you had instead of the actual errors, like syntax errors or unknown class names. Try cleaning the solution and building project after project. This way you will discover the actual errors.

Again, this is just what cause the error for me.

How can I send JSON response in symfony2 controller

Symfony 2.1

$response = new Response(json_encode(array('name' => $name)));
$response->headers->set('Content-Type', 'application/json');

return $response;

Symfony 2.2 and higher

You have special JsonResponse class, which serialises array to JSON:

return new JsonResponse(array('name' => $name));

But if your problem is How to serialize entity then you should have a look at JMSSerializerBundle

Assuming that you have it installed, you'll have simply to do

$serializedEntity = $this->container->get('serializer')->serialize($entity, 'json');

return new Response($serializedEntity);

You should also check for similar problems on StackOverflow:

Write a file on iOS


func saveFile() {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let documentsDirectory = paths[0] as! String
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content = "Hello World"
    content.writeToFile(fileName, atomically: false, encoding: NSUTF8StringEncoding, error: nil)

func loadFile() {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let documentsDirectory = paths[0] as! String
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content: String = String(contentsOfFile: fileName, encoding: NSUTF8StringEncoding, error: nil)!

Swift 2

func saveFile() {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let documentsDirectory = paths[0]
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content = "Hello World"
        try content.writeToFile(fileName, atomically: false, encoding: NSUTF8StringEncoding)
    }catch _ {



func loadFile()->String {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let documentsDirectory = paths[0] 
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content: String
       content = try String(contentsOfFile: fileName, encoding: NSUTF8StringEncoding)
    }catch _{
    return content;

Swift 3

func saveFile() {
    let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    let documentsDirectory = paths[0]
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content = "Hello World"
        try content.write(toFile: fileName, atomically: false, encoding: String.Encoding.utf8)
    }catch _ {



func loadFile()->String {
    let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    let documentsDirectory = paths[0]
    let fileName = "\(documentsDirectory)/textFile.txt"
    let content: String
        content = try String(contentsOfFile: fileName, encoding: String.Encoding.utf8)
    } catch _{
    return content;

The located assembly's manifest definition does not match the assembly reference

A general answer to this kind of issue is to use binding redirects as in other answers. However, that's only part of the problem - you need to know the correct version of the assembly file that you're using. Windows properties is not always accurate and nuget is also not always accurate.

The only way to get correct version info is to analyse the file itself. One useful tool is dotPeek. The assembly name listed in dotPeek is always accurate in my experience.

So for example, the correct binding for this file is the following:

    <assemblyIdentity name="System.ComponentModel.Annotations" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
    <bindingRedirect oldVersion="" newVersion=""/>

Windows explorer says the file is 4.6.26515.06, nuget says its a file. dotPeek says it is and that is the version that works correctly in our software. Also note that the public key and culture are important and dotPeek also show this information.

dotPeek vs Windows version information

Is it possible to remove the hand cursor that appears when hovering over a link? (or keep it set as the normal pointer)

  <a href=""
     style="cursor:default">sign in</a>

Where does the slf4j log file get saved?

The log file is not visible because the slf4j configuration file location needs to passed to the java run command using the following arguments .(e.g.)


or this:


Javascript to convert UTC to local time

The solutions above are right but might crash in FireFox and Safari! and that's what webility.js is trying to solve. Check the toUTC function, it works on most of the main browers and it returns the time in ISO format

Is there a way to add a gif to a Markdown file?

just upload the .gif file into your base folder of GitHub and edit just use this code


How to print a Groovy variable in Jenkins?

The following code worked for me:

echo userInput

DataTables: Cannot read property 'length' of undefined

When you have JSON data then the following error appears enter image description here

A better solution is to assign a var data for the local json array object, details see:

This is helps you to display table contents.


        $('#customer_table').DataTable( {
         "aaData": data,

           "aoColumns": [{
                            "mDataProp": "name_en"
                        }, {
                            "mDataProp": "phone"
                        }, {
                            "mDataProp": "email"
                        }, {
                            "mDataProp": "facebook"

Comparing HTTP and FTP for transferring files

Here's a performance comparison of the two. HTTP is more responsive for request-response of small files, but FTP may be better for large files if tuned properly. FTP used to be generally considered faster. FTP requires a control channel and state be maintained besides the TCP state but HTTP does not. There are 6 packet transfers before data starts transferring in FTP but only 4 in HTTP.

I think a properly tuned TCP layer would have more effect on speed than the difference between application layer protocols. The Sun Blueprint Understanding Tuning TCP has details.

Heres another good comparison of individual characteristics of each protocol.

Bind class toggle to window scroll event

This is my solution, it's not that tricky and allow you to use it for several markup throught a simple ng-class directive. Like so you can choose the class and the scrollPos for each case.

Your App.js :

    .controller('mainCtrl',function($window, $scope){
        $scope.scrollPos = 0;

        $window.onscroll = function(){
            $scope.scrollPos = document.body.scrollTop || document.documentElement.scrollTop || 0;
            $scope.$apply(); //or simply $scope.$digest();

Your index.html :

<html ng-app="myApp">
        <section ng-controller="mainCtrl">
            <p class="red" ng-class="{fix:scrollPos >= 100}">fix me when scroll is equals to 100</p>
            <p class="blue" ng-class="{fix:scrollPos >= 150}">fix me when scroll is equals to 150</p>

working JSFiddle here


As $apply() is actually calling $rootScope.$digest() you can directly use $scope.$digest() instead of $scope.$apply() for better performance depending on context.
Long story short : $apply() will always work but force the $digest on all scopes that may cause perfomance issue.

Maven Java EE Configuration Marker with Java Server Faces 1.2

I have encountered this with Maven projects too. This is what I had to do to get around the problem:

First update your web.xml

<web-app xmlns="" 
<display-name>Servlet 3.0 Web Application</display-name>

Then right click on your project and select Properties -> Project Facets In there you will see the version of your Dynamic Web Module. This needs to change from version 2.3 or whatever to version 2.5 or above (I chose 3.0).

However to do this I had to uncheck the tick box for Dynamic Web Module -> Apply, then do a Maven Update on the project. Go back into the Project Facets window and it should already match your web.xml configuration - 3.0 in my case. You should be able to change it if not.

If this does not work for you then try right-clicking on the Dynamic Web Module Facet and select change version (and ensure it is not locked).

Or you can follow this steps:

  1. Window > Show View > Other > General > navigator
  2. There is a .settings folder under your project directory
  3. Change the dynamic web module version in this line to 3.0
  4. Change the Java version in this line to 1.5 or higher

don't forget to update your project

Hope that works!

getMinutes() 0-9 - How to display two digit numbers?

Elegant ES6 function to format a date into hh:mm:ss:

const leadingZero = (num) => `0${num}`.slice(-2);

const formatTime = (date) =>
  [date.getHours(), date.getMinutes(), date.getSeconds()]

what is the use of annotations @Id and @GeneratedValue(strategy = GenerationType.IDENTITY)? Why the generationtype is identity?

Simply, @Id: This annotation specifies the primary key of the entity. 

@GeneratedValue: This annotation is used to specify the primary key generation strategy to use. i.e Instructs database to generate a value for this field automatically. If the strategy is not specified by default AUTO will be used. 

GenerationType enum defines four strategies: 
1. Generation Type . TABLE, 
2. Generation Type. SEQUENCE,
3. Generation Type. IDENTITY   
4. Generation Type. AUTO


With this strategy, underlying persistence provider must use a database sequence to get the next unique primary key for the entities. 


With this strategy, underlying persistence provider must use a database table to generate/keep the next unique primary key for the entities. 

This GenerationType indicates that the persistence provider must assign primary keys for the entity using a database identity column. IDENTITY column is typically used in SQL Server. This special type column is populated internally by the table itself without using a separate sequence. If underlying database doesn't support IDENTITY column or some similar variant then the persistence provider can choose an alternative appropriate strategy. In this examples we are using H2 database which doesn't support IDENTITY column.

This GenerationType indicates that the persistence provider should automatically pick an appropriate strategy for the particular database. This is the default GenerationType, i.e. if we just use @GeneratedValue annotation then this value of GenerationType will be used. 


How to autoplay HTML5 mp4 video on Android?

<video autoplay controls id='video1' width='100%' poster='images/top_icon.png' webkitEnterFullscreen poster preload='true'>
<source src='' type='video/mp4; codecs='avc1.42E01E, mp4a.40.2' >

For loop in Oracle SQL

You are pretty confused my friend. There are no LOOPS in SQL, only in PL/SQL. Here's a few examples based on existing Oracle table - copy/paste to see results:

-- Numeric FOR loop --
set serveroutput on -->> do not use in TOAD --
  k NUMBER:= 0;
  FOR i IN 1..10 LOOP
    k:= k+1;
    dbms_output.put_line(i||' '||k);

-- Cursor FOR loop --
set serveroutput on
   CURSOR c1 IS SELECT * FROM scott.emp;
   i NUMBER:= 0;
  FOR e_rec IN c1 LOOP
  i:= i+1;

-- SQL example to generate 10 rows --
SELECT 1 + LEVEL-1 idx
  FROM dual

The view or its master was not found or no view engine supports the searched locations

Be careful if your model type is String because the second parameter of View(string, string) is masterName, not model. You may need to call the overload with object(model) as the second paramater:

Not correct :

protected ActionResult ShowMessageResult(string msg)
    return View("Message",msg);

Correct :

protected ActionResult ShowMessageResult(string msg)
    return View("Message",(object)msg);

OR (provided by bradlis7):

protected ActionResult ShowMessageResult(string msg)
    return View("Message",model:msg);

How the int.TryParse actually works

Regex is compiled so for speed create it once and reuse it.
The new takes longer than the IsMatch.
This only checks for all digits.
It does not check for range.
If you need to test range then TryParse is the way to go.

private static Regex regexInt = new Regex("^\\d+$");
static bool CheckReg(string value)
    return regexInt.IsMatch(value);

Generating sql insert into for Oracle

You can do that in PL/SQL Developer v10.
1. Click on Table that you want to generate script for.
2. Click Export data.
3. Check if table is selected that you want to export data for.
4. Click on SQL inserts tab.
5. Add where clause if you don't need the whole table.
6. Select file where you will find your SQL script.
7. Click export.
enter image description here

DataSet panel (Report Data) in SSRS designer is gone

For future people CTRL+ALT+D or just view > report data in ancient ssrs 2008 VS BI. In newer 2017 SSRS, it's still the same. Funny how they change a bunch of things around, yet kept this the same.

How can I use tabs for indentation in IntelliJ IDEA?

To expand on @Dmitiri Algazin 's answer: settings for individual languages are overridden by the general setting

Preferences -> Code Style -> Detect and use existing file indents for editing

So if you are wondering why your new settings are being ignored after changing your settings for a specific language, there is a chance this checkbox is ticked.

As a side note; changing any default settings automamagically creates a settings profile clone (i.e. Default(1)) which I assume is in place so that the default IDE settings are never overwritten.

It is a little confusing at first, really, whether editing Default settings or Project Settings is going to have any effect on your project, since you can select Default from the drop down menu and then edit from there.

If you don't want to keep seeing random clones of Default populating your settings profiles, edit the Project Settings directly.

How to send control+c from a bash script?

ctrl+c and kill -INT <pid> are not exactly the same, to emulate ctrl+c we need to first understand the difference.

kill -INT <pid> will send the INT signal to a given process (found with its pid).

ctrl+c is mapped to the intr special character which when received by the terminal should send INT to the foreground process group of that terminal. You can emulate that by targetting the group of your given <pid>. It can be done by prepending a - before the signal in the kill command. Hence the command you want is:

kill -INT -<pid>

You can test it pretty easily with a script:

#!/usr/bin/env ruby

fork {
    trap(:INT) {
        puts 'signal received in child!'
    sleep 1_000

puts "run `kill -INT -#{}` in any other terminal window."


How to get StackPanel's children to fill maximum space downward?

You can use SpicyTaco.AutoGrid - a modified version of StackPanel:

<st:StackPanel Orientation="Horizontal" MarginBetweenChildren="10" Margin="10">
   <Button Content="Info" HorizontalAlignment="Left" st:StackPanel.Fill="Fill"/>
   <Button Content="Cancel"/>
   <Button Content="Save"/>

First button will be fill.

You can install it via NuGet:

Install-Package SpicyTaco.AutoGrid

I recommend taking a look at SpicyTaco.AutoGrid. It's very useful for forms in WPF instead of DockPanel, StackPanel and Grid and solve problem with stretching very easy and gracefully. Just look at readme on GitHub.

<st:AutoGrid Columns="160,*" ChildMargin="3">
    <Label Content="Name:"/>

    <Label Content="E-Mail:"/>

    <Label Content="Comment:"/>

C# Linq Group By on multiple columns

Given a list:

var list = new List<Child>()
    new Child()
        {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "John"},
    new Child()
        {School = "School2", FavoriteColor = "blue", Friend = "Bob", Name = "Pete"},
    new Child()
        {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "Fred"},
    new Child()
        {School = "School2", FavoriteColor = "blue", Friend = "Fred", Name = "Bob"},

The query would look like:

var newList = list
    .GroupBy(x => new {x.School, x.Friend, x.FavoriteColor})
    .Select(y => new ConsolidatedChild()
            FavoriteColor = y.Key.FavoriteColor,
            Friend = y.Key.Friend,
            School = y.Key.School,
            Children = y.ToList()

Test code:

foreach(var item in newList)
    Console.WriteLine("School: {0} FavouriteColor: {1} Friend: {2}", item.School,item.FavoriteColor,item.Friend);
    foreach(var child in item.Children)
        Console.WriteLine("\t Name: {0}", child.Name);


School: School1 FavouriteColor: blue Friend: Bob
    Name: John
    Name: Fred
School: School2 FavouriteColor: blue Friend: Bob
    Name: Pete
School: School2 FavouriteColor: blue Friend: Fred
    Name: Bob

How to pull remote branch from somebody else's repo

git remote add coworker git://path/to/coworkers/repo.git
git fetch coworker
git checkout --track coworker/foo

This will setup a local branch foo, tracking the remote branch coworker/foo. So when your co-worker has made some changes, you can easily pull them:

git checkout foo
git pull

Response to comments:

Cool :) And if I'd like to make my own changes to that branch, should I create a second local branch "bar" from "foo" and work there instead of directly on my "foo"?

You don't need to create a new branch, even though I recommend it. You might as well commit directly to foo and have your co-worker pull your branch. But that branch already exists and your branch foo need to be setup as an upstream branch to it:

git branch --set-upstream foo colin/foo

assuming colin is your repository (a remote to your co-workers repository) defined in similar way:

git remote add colin git://path/to/colins/repo.git

Regular expression to match any character being repeated more than 10 times

The regex you need is /(.)\1{9,}/.


use warnings;
use strict;
my $regex = qr/(.)\1{9,}/;
print "NO" if "abcdefghijklmno" =~ $regex;
print "YES" if "------------------------" =~ $regex;
print "YES" if "========================" =~ $regex;

Here the \1 is called a backreference. It references what is captured by the dot . between the brackets (.) and then the {9,} asks for nine or more of the same character. Thus this matches ten or more of any single character.

Although the above test script is in Perl, this is very standard regex syntax and should work in any language. In some variants you might need to use more backslashes, e.g. Emacs would make you write \(.\)\1\{9,\} here.

If a whole string should consist of 9 or more identical characters, add anchors around the pattern:

my $regex = qr/^(.)\1{9,}$/;

How do I create an empty array/matrix in NumPy?

To create an empty multidimensional array in NumPy (e.g. a 2D array m*n to store your matrix), in case you don't know m how many rows you will append and don't care about the computational cost Stephen Simmons mentioned (namely re-buildinging the array at each append), you can squeeze to 0 the dimension to which you want to append to: X = np.empty(shape=[0, n]).

This way you can use for example (here m = 5 which we assume we didn't know when creating the empty matrix, and n = 2):

import numpy as np

n = 2
X = np.empty(shape=[0, n])

for i in range(5):
    for j  in range(2):
        X = np.append(X, [[i, j]], axis=0)

print X

which will give you:

[[ 0.  0.]
 [ 0.  1.]
 [ 1.  0.]
 [ 1.  1.]
 [ 2.  0.]
 [ 2.  1.]
 [ 3.  0.]
 [ 3.  1.]
 [ 4.  0.]
 [ 4.  1.]]

What is let-* in Angular 2 templates?

The Angular microsyntax lets you configure a directive in a compact, friendly string. The microsyntax parser translates that string into attributes on the <ng-template>. The let keyword declares a template input variable that you reference within the template.

Select top 2 rows in Hive

select * from employee_list order by salary desc limit 2;

How to write a caption under an image?

Put the image — let's say it's width is 140px — inside of a link:

<a><img src='image link' style='width: 140px'></a>

Next, put the caption in a and give it a width less than your image, while centering it:

  <img src='image link' style='width: 140px'>
  <div style='width: 130px; text-align: center;'>I just love to visit this most beautiful place in all the world.</div>

Next, in the link tag, style the link so that it no longer looks like a link. You can give it any color you want, but just remove any text decoration your links may carry.

<a style='text-decoration: none; color: orange;'>
  <img src='image link' style='width: 140px'>
  <div style='width: 130px; text-align: center;'>I just love to visit this most beautiful place in all the world.</div>

I wrapped the image with it's caption in a link so that no text could push the caption out of the way: The caption is tied to the picture by the link. Here's an example:

Insert all values of a table into another table in SQL

If you are transferring a lot data permanently, i.e not populating a temp table, I would recommend using SQL Server Import/Export Data for table-to-table mappings.

Import/Export tool is usually better than straight SQL when you have type conversions and possible value truncation in your mapping. Generally, the more complex your mapping, the more productive you are using an ETL tool like Integration Services (SSIS) instead of direct SQL.

Import/Export tool is actually an SSIS wizard, and you can save your work as a dtsx package.

Resource files not found from JUnit test cases

The test Resource files(src/test/resources) are loaded to target/test-classes sub folder. So we can use the below code to load the test resource files.

String resource = "sample.txt";
File file = new File(getClass().getClassLoader().getResource(resource).getFile());


Note : Here the sample.txt file should be placed under src/test/resources folder.

For more details refer options_to_load_test_resources

How can I convert a long to int in Java?

In Java 8 I do in following way

long l = 100L;
int i = Math.toIntExact(l);

This method throws ArithmaticException if long value exceed range of int. Thus I am safe from data loss.

How to get value from form field in django framework?

It is easy if you are using django version 3.1 and above

def login_view(request):
        yourForm= YourForm(request.POST)
        itemValue = yourForm['your_filed_name'].value()
        # Check if you get the value
        return HttpResponse(itemValue )
        return render(request, "base.html")

How to open every file in a folder

you should try using os.walk

yourpath = 'path'

import os
for root, dirs, files in os.walk(yourpath, topdown=False):
    for name in files:
        print(os.path.join(root, name))
    for name in dirs:
        print(os.path.join(root, name))

What is a Memory Heap?

A memory heap is a common structure for holding dynamically allocated memory. See Dynamic_memory_allocation on wikipedia.

There are other structures, like pools, stacks and piles.

Eclipse Optimize Imports to Include Static Imports

For SpringFramework Tests, I would recommend to add the below as well


When you add above as new Type it automatically add .* to the package.

Simulating Button click in javascript

Since you are using jQuery you can use this onClick handler which calls click:


This is the same as $("#datepicker").trigger("click").

For a jQuery-free version check out this answer on SO.

Delete all nodes and relationships in neo4j 1.8

Probably you will want to delete Constraints and Indexes

jQuery UI DatePicker to show year only

  $(function() {
    $('#datepicker1').datepicker( {
        changeMonth: true,
        changeYear: true,
        showButtonPanel: true,
        dateFormat: 'MM yy',
        onClose: function(dateText, inst) { 
            var month = $("#ui-datepicker-div .ui-datepicker-month :selected").val();
            var year = $("#ui-datepicker-div .ui-datepicker-year :selected").val();
            $(this).datepicker('setDate', new Date(year, month, 1));

Style should be

.ui-datepicker-calendar {
    display: none;

working demo

jQuery - on change input text

function search() {
        var query_value = $('input#search').val();
        if(query_value !== ''){
                type: "POST",
                url: "search.php",
                data: { query: query_value },
                cache: false,
                success: function(html){
        }return false;    

    $("input#search").live("keyup", function(e) {
        clearTimeout($.data(this, 'timer'));

        var search_string = $(this).val();

        if (search_string == '') {
            $(this).data('timer', setTimeout(search, 100));

and the html 
<input id="search" style="height:36px; font-size:13px;" type="text" class="form-control" placeholder="Enter Mobile Number or Email"  value="<?php echo stripcslashes($_REQUEST["string"]); ?>" name="string" />
        <h4 id="results-text">Showing results for: <b id="search-string">Array</b></h4>
        <ul id="results"></ul>

Switch statement fall-through...should it be allowed?

Have you heard of Duff's device? This is a great example of using switch fallthrough.

It's a feature that can be used and it can be abused, like almost all language features.

LINQ order by null column where order is ascending and nulls should be last

The solution for string values is really weird:

.OrderBy(f => f.SomeString == null).ThenBy(f => f.SomeString) 

The only reason that works is because the first expression, OrderBy(), sort bool values: true/false. false result go first follow by the true result (nullables) and ThenBy() sort the non-null values alphabetically.

e.g.: [null, "coconut", null, "apple", "strawberry"]
First sort: ["coconut", "apple", "strawberry", null, null]
Second sort: ["apple", "coconut", "strawberry", null, null]
So, I prefer doing something more readable such as this:
.OrderBy(f => f.SomeString ?? "z")

If SomeString is null, it will be replaced by "z" and then sort everything alphabetically.

NOTE: This is not an ultimate solution since "z" goes first than z-values like zebra.

UPDATE 9/6/2016 - About @jornhd comment, it is really a good solution, but it still a little complex, so I will recommend to wrap it in a Extension class, such as this:

public static class MyExtensions
    public static IOrderedEnumerable<T> NullableOrderBy<T>(this IEnumerable<T> list, Func<T, string> keySelector)
        return list.OrderBy(v => keySelector(v) != null ? 0 : 1).ThenBy(keySelector);

And simple use it like:

var sortedList = list.NullableOrderBy(f => f.SomeString);

Border in shape xml

It looks like you forgot the prefix on the color attribute. Try

 <stroke android:width="2dp" android:color="#ff00ffff"/>

How to determine if .NET Core is installed

Run this command

dotnet --list-sdks

enter image description here

Why can a function modify some arguments as perceived by the caller, but not others?

Python is a pure pass-by-value language if you think about it the right way. A python variable stores the location of an object in memory. The Python variable does not store the object itself. When you pass a variable to a function, you are passing a copy of the address of the object being pointed to by the variable.

Contrasst these two functions

def foo(x):
    x[0] = 5

def goo(x):
    x = []

Now, when you type into the shell

>>> cow = [3,4,5]
>>> foo(cow)
>>> cow

Compare this to goo.

>>> cow = [3,4,5]
>>> goo(cow)
>>> goo

In the first case, we pass a copy the address of cow to foo and foo modified the state of the object residing there. The object gets modified.

In the second case you pass a copy of the address of cow to goo. Then goo proceeds to change that copy. Effect: none.

I call this the pink house principle. If you make a copy of your address and tell a painter to paint the house at that address pink, you will wind up with a pink house. If you give the painter a copy of your address and tell him to change it to a new address, the address of your house does not change.

The explanation eliminates a lot of confusion. Python passes the addresses variables store by value.

Change Default branch in gitlab

in the GitLab Enterprise Edition 12.2.0-pre you have to use following: Setting ? Repository ? Default Branch ( expand it) and change the default branch Here

Is there a format code shortcut for Visual Studio?

Ctrl + K + D (Entire document)

Ctrl + K + F (Selection only)

Styling an input type="file" button

Plug-in solutions I found were too heavy-weight, so, I made my own jQuery plug-in called Drolex FileStyle.

This plug-in allows you to style file input fields however you want. Actually, you style div elements to look like a tricked out file input, and the actual file input is automatically overlaid with 0% opacity. No additional HTML is required. Just include the css and js files in the page you want Drolex FileStyle and that's it! Edit the css file to your liking. Don't forget the jQuery library if your page doesn't already have it. If the client does not run JavaScript, then the file input will not be modified by js or css.

Tested to work in Chrome 24, Firefox 18, Internet Explorer 9. Expected to work in previous versions of those and others.


How to get a MemoryStream from a Stream in .NET?

How do I copy the contents of one stream to another?

see that. accept a stream and copy to memory. you should not use .Length for just Stream because it is not necessarily implemented in every concrete Stream.

How to declare Global Variables in Excel VBA to be visible across the Workbook

You can do the following to learn/test the concept:

  1. Open new Excel Workbook and in Excel VBA editor right-click on Modules->Insert->Module

  2. In newly added Module1 add the declaration; Public Global1 As String

  3. in Worksheet VBA Module Sheet1(Sheet1) put the code snippet:

Sub setMe()
      Global1 = "Hello"
End Sub
  1. in Worksheet VBA Module Sheet2(Sheet2) put the code snippet:
Sub showMe()
    Debug.Print (Global1)
End Sub
  1. Run in sequence Sub setMe() and then Sub showMe() to test the global visibility/accessibility of the var Global1

Hope this will help.

Configure hibernate (using JPA) to store Y/N for type Boolean instead of 0/1

I used the concept from the answer posted by @marcg and it works great with JPA 2.1. His code wasn't quite right, so I'm posted my working implementation. This will convert Boolean entity fields to a Y/N character column in the database.

From my entity class:

@Column(name="LOADED", length=1)
private Boolean isLoadedSuccessfully;

My converter class:

 * Converts a Boolean entity attribute to a single-character
 * Y/N string that will be stored in the database, and vice-versa
 * @author jtough
public class BooleanToYNStringConverter 
        implements AttributeConverter<Boolean, String> {

     * This implementation will return "Y" if the parameter is Boolean.TRUE,
     * otherwise it will return "N" when the parameter is Boolean.FALSE. 
     * A null input value will yield a null return value.
     * @param b Boolean
    public String convertToDatabaseColumn(Boolean b) {
        if (b == null) {
            return null;
        if (b.booleanValue()) {
            return "Y";
        return "N";

     * This implementation will return Boolean.TRUE if the string
     * is "Y" or "y", otherwise it will ignore the value and return
     * Boolean.FALSE (it does not actually look for "N") for any
     * other non-null string. A null input value will yield a null
     * return value.
     * @param s String
    public Boolean convertToEntityAttribute(String s) {
        if (s == null) {
            return null;
        if (s.equals("Y") || s.equals("y")) {
            return Boolean.TRUE;
        return Boolean.FALSE;


This variant is also fun if you love emoticons and are just sick and tired of Y/N or T/F in your database. In this case, your database column must be two characters instead of one. Probably not a big deal.

 * Converts a Boolean entity attribute to a happy face or sad face
 * that will be stored in the database, and vice-versa
 * @author jtough
public class BooleanToHappySadConverter 
        implements AttributeConverter<Boolean, String> {

    public static final String HAPPY = ":)";
    public static final String SAD = ":(";

     * This implementation will return ":)" if the parameter is Boolean.TRUE,
     * otherwise it will return ":(" when the parameter is Boolean.FALSE. 
     * A null input value will yield a null return value.
     * @param b Boolean
     * @return String or null
    public String convertToDatabaseColumn(Boolean b) {
        if (b == null) {
            return null;
        if (b) {
            return HAPPY;
        return SAD;

     * This implementation will return Boolean.TRUE if the string
     * is ":)", otherwise it will ignore the value and return
     * Boolean.FALSE (it does not actually look for ":(") for any
     * other non-null string. A null input value will yield a null
     * return value.
     * @param s String
     * @return Boolean or null
    public Boolean convertToEntityAttribute(String s) {
        if (s == null) {
            return null;
        if (HAPPY.equals(s)) {
            return Boolean.TRUE;
        return Boolean.FALSE;


How to add a new object (key-value pair) to an array in javascript?

.push() will add elements to the end of an array.

Use .unshift() if need to add some element to the beginning of array i.e:



items = [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}];_x000D_
items.unshift({'id': 0});_x000D_

And use .splice() in case you want to add object at a particular index i.e:

items.splice(2, 0, {'id':5});
           // ^ Given object will be placed at index 2...


items = [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}];_x000D_
items.splice(2, 0, {'id': 2.5});_x000D_

Efficient way to return a std::vector in c++

A common pre-C++11 idiom is to pass a reference to the object being filled.

Then there is no copying of the vector.

void f( std::vector & result )
    Insert elements into result

Using StringWriter for XML Serialization

One problem with StringWriter is that by default it doesn't let you set the encoding which it advertises - so you can end up with an XML document advertising its encoding as UTF-16, which means you need to encode it as UTF-16 if you write it to a file. I have a small class to help with that though:

public sealed class StringWriterWithEncoding : StringWriter
    public override Encoding Encoding { get; }

    public StringWriterWithEncoding (Encoding encoding)
        Encoding = encoding;

Or if you only need UTF-8 (which is all I often need):

public sealed class Utf8StringWriter : StringWriter
    public override Encoding Encoding => Encoding.UTF8;

As for why you couldn't save your XML to the database - you'll have to give us more details about what happened when you tried, if you want us to be able to diagnose/fix it.

What is com.sun.proxy.$Proxy

  1. Proxies are classes that are created and loaded at runtime. There is no source code for these classes. I know that you are wondering how you can make them do something if there is no code for them. The answer is that when you create them, you specify an object that implements InvocationHandler, which defines a method that is invoked when a proxy method is invoked.

  2. You create them by using the call

    Proxy.newProxyInstance(classLoader, interfaces, invocationHandler)

    The arguments are:

    1. classLoader. Once the class is generated, it is loaded with this class loader.
    2. interfaces. An array of class objects that must all be interfaces. The resulting proxy implements all of these interfaces.
    3. invocationHandler. This is how your proxy knows what to do when a method is invoked. It is an object that implements InvocationHandler. When a method from any of the supported interfaces, or hashCode, equals, or toString, is invoked, the method invoke is invoked on the handler, passing the Method object for the method to be invoked and the arguments passed.

    For more on this, see the documentation for the Proxy class.

  3. Every implementation of a JVM after version 1.3 must support these. They are loaded into the internal data structures of the JVM in an implementation-specific way, but it is guaranteed to work.

Could not resolve '...' from state ''

I had a case where the error was thrown by a


Which is obvious. I guess this can help someone in future.

File inside jar is not visible for spring

In the spring jar package, I use new ClassPathResource(filename).getFile(), which throws the exception:

cannot be resolved to absolute file path because it does not reside in the file system: jar

But using new ClassPathResource(filename).getInputStream() will solve this problem. The reason is that the configuration file in the jar does not exist in the operating system's file tree,so must use getInputStream().

How to escape the % (percent) sign in C's printf?

Yup, use printf("hello%%"); and it's done.

The EntityManager is closed

In controller.

Exception closes the Entity Manager. This makes troubles for bulk insert. To continue, need to redefine it.

* @var  \Doctrine\ORM\EntityManager
$em = $this->getDoctrine()->getManager();

foreach($to_insert AS $data)
        $em = $this->getDoctrine()->getManager();

  $entity = new \Entity();

  catch(\Doctrine\DBAL\DBALException $e)
    if($e->getPrevious()->getCode() != '23000')
      * if its not the error code for a duplicate key 
      * value then rethrow the exception
      throw $e;

Want to show/hide div based on dropdown box selection

you have error in your code unexpected token.use:

  $('#purpose').on('change', function () {
   if (this.value == '1') {
    } else {



Update: You can narrow down the code using .toggle()

 $('#purpose').on('change', function () {
   $("#business").toggle(this.value == '1');

Uncaught ReferenceError: function is not defined with onclick

Never use .onclick(), or similar attributes from a userscript! (It's also poor practice in a regular web page).

The reason is that userscripts operate in a sandbox ("isolated world"), and onclick operates in the target-page scope and cannot see any functions your script creates.

Always use addEventListener()Doc (or an equivalent library function, like jQuery .on()).

So instead of code like:

something.outerHTML += '<input onclick="resetEmotes()" id="btnsave" ...>'

You would use:

something.outerHTML += '<input id="btnsave" ...>'

document.getElementById ("btnsave").addEventListener ("click", resetEmotes, false);

For the loop, you can't pass data to an event listener like that See the doc. Plus every time you change innerHTML like that, you destroy the previous event listeners!

Without refactoring your code much, you can pass data with data attributes. So use code like this:

for (i = 0; i < EmoteURLLines.length; i++) {
    if (checkIMG (EmoteURLLines[i])) {
        localStorage.setItem ("nameEmotes", JSON.stringify (EmoteNameLines));
        localStorage.setItem ("urlEmotes", JSON.stringify (EmoteURLLines));
        localStorage.setItem ("usageEmotes", JSON.stringify (EmoteUsageLines));
        if (i == 0) {
            console.log (resetSlot ());
        emoteTab[2].innerHTML  += '<span style="cursor:pointer;" id="' 
                                + EmoteNameLines[i] 
                                + '" data-usage="' + EmoteUsageLines[i] + '">'
                                + '<img src="' + EmoteURLLines[i] + '" /></span>'
    } else {
        alert ("The maximum emote (" + EmoteNameLines[i] + ") size is (36x36)");
//-- Only add events when innerHTML overwrites are done.
var targetSpans = emoteTab[2].querySelectorAll ("span[data-usage]");
for (var J in targetSpans) {
    targetSpans[J].addEventListener ("click", appendEmote, false);

Where appendEmote is like:

function appendEmote (zEvent) {
    //-- this and the parameter are special in event handlers.  see the linked doc.
    var emoteUsage  = this.getAttribute ("data-usage");
    shoutdata.value += emoteUsage;


  • Your code reuses the same id for several elements. Don't do this, it's invalid. A given ID should occur only once per page.
  • Every time you use .outerHTML or .innerHTML, you trash any event handlers on the affected nodes. If you use this method beware of that fact.

How do I convert a string to a double in Python?

>>> x = "2342.34"
>>> float(x)

There you go. Use float (which behaves like and has the same precision as a C,C++, or Java double).

Padding characters in printf

Pure Bash. Use the length of the value of 'PROC_NAME' as offset for the fixed string 'line':

printf "%s %s [UP]\n" $PROC_NAME "${line:${#PROC_NAME}}"
printf "%s %s [UP]\n" $PROC_NAME "${line:${#PROC_NAME}}"

This gives

abc ------------------------------------- [UP]
abcdef ---------------------------------- [UP]

Converting a String array into an int Array in java

To help debug, and make your code better, do this:

private void processLine(String[] strings) {
    Integer[] intarray=new Integer[strings.length];
    int i=0;
    for(String str:strings){
        try {
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException("Not a number: " + str + " at index " + i, e);

Also, from a code neatness point, you could reduce the lines by doing this:

for (String str : strings)
    intarray[i++] = Integer.parseInt(str);

creating charts with angularjs

To collect more useful resources here:

As mentioned before D3.js is definitely the best visualization library for charts. To use it in AngularJS I developed angular-chart. It is an easy to use directive which connects D3.js with the AngularJS 2-Way-DataBinding. This way the chart gets automatically updated whenever you change the configuration options and at the same time the charts saves its state (zoom level, ...) to make it available in the AngularJS world.

Check out the examples to get convinced.

Is it bad practice to use break to exit a loop in Java?

While its not bad practice to use break and there are many excellent uses for it, it should not be all you rely upon. Almost any use of a break can be written into the loop condition. Code is far more readable when real conditions are used, but in the case of a long-running or infinite loop, breaks make perfect sense. They also make sense when searching for data, as shown above.

How to get string objects instead of Unicode from JSON?

That's because json has no difference between string objects and unicode objects. They're all strings in javascript.

I think JSON is right to return unicode objects. In fact, I wouldn't accept anything less, since javascript strings are in fact unicode objects (i.e. JSON (javascript) strings can store any kind of unicode character) so it makes sense to create unicode objects when translating strings from JSON. Plain strings just wouldn't fit since the library would have to guess the encoding you want.

It's better to use unicode string objects everywhere. So your best option is to update your libraries so they can deal with unicode objects.

But if you really want bytestrings, just encode the results to the encoding of your choice:

>>> nl = json.loads(js)
>>> nl
[u'a', u'b']
>>> nl = [s.encode('utf-8') for s in nl]
>>> nl
['a', 'b']

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

The problem is the JSON - this cannot, by default, be deserialized into a Collection because it's not actually a JSON Array - that would look like this:

        "name": "Test order1",
        "detail": "ahk ks"
        "name": "Test order2",
        "detail": "Fisteku"

Since you're not controlling the exact process of deserialization (RestEasy does) - a first option would be to simply inject the JSON as a String and then take control of the deserialization process:

Collection<COrder> readValues = new ObjectMapper().readValue(
    jsonAsString, new TypeReference<Collection<COrder>>() { }

You would loose a bit of the convenience of not having to do that yourself, but you would easily sort out the problem.

Another option - if you cannot change the JSON - would be to construct a wrapper to fit the structure of your JSON input - and use that instead of Collection<COrder>.

Hope this helps.

Autocompletion in Vim

I'm a bit late to the party but autocomplpop might be helpful.

Can grep show only words that match search pattern?

To search all the words with start with "icon-" the following command works perfect. I am using Ack here which is similar to grep but with better options and nice formatting.

ack -oh --type=html "\w*icon-\w*" | sort | uniq

What is the difference between a static and const variable?


is used for making the variable a class variable. You need not define a static variable while declaring.


#include <iostream>

class dummy
                static int dum;

int dummy::dum = 0; //This is important for static variable, otherwise you'd get a linking error

int main()
        dummy d;
        d.dum = 1;

        std::cout<<"Printing dum from object: "<<d.dum<<std::endl;
        std::cout<<"Printing dum from class: "<<dummy::dum<<std::endl;

        return 0;

This would print: Printing dum from object: 1 Printing dum from class: 1

The variable dum is a class variable. Trying to access it via an object just informs the compiler that it is a variable of which class. Consider a scenario where you could use a variable to count the number of objects created. static would come in handy there.


is used to make it a read-only variable. You need to define and declare the const variable at once.

In the same program mentioned above, let's make the dum a const as well:

class dummy
                static const int dum; // This would give an error. You need to define it as well
                static const int dum = 1; //this is correct
                const int dum = 1; //Correct. Just not making it a class variable


Suppose in the main, I am doing this:

int main()
        dummy d;
        d.dum = 1; //Illegal!

        std::cout<<"Printing dum from object: "<<d.dum<<std::endl;
        std::cout<<"Printing dum from class: "<<dummy::dum<<std::endl;

        return 0;

Though static has been manageable to understand, const is messed up in c++. The following resource helps in understanding it better:

Correct way to try/except using Python requests module?

Exception object also contains original response e.response, that could be useful if need to see error body in response from the server. For example:

    r ='', data={'birthday': '9/9/3999'})
except requests.exceptions.HTTPError as e:
    print (e.response.text)

Two Divs next to each other, that then stack with responsive change

today this kind of thing can be done by using display:flex;


  <div class="container flex-direction">
      <div class="div1">
        <span>Div One</span>
      <div class="div2">
        <span>Div Two</span>


  border:1px solid black;
  border-right:1px solid black;


    display: block;
    line-height: 132px;
    text-align: center;

@media screen and (max-width: 500px) {
  border-bottom:1px solid black;
  .div2 span{


jQuery: Selecting by class and input type

Your selector is looking for any descendants of a checkbox element that have a class of .myClass.

Try this instead:


Check it out in action.

I also tested this:


And it will also work properly. In my humble opinion this syntax really looks rather ugly, as most of the time I expect : style selectors to come last. As I said, though, either one will work.

Android- Error:Execution failed for task ':app:transformClassesWithDexForRelease'

I did receive also the same error:

Error:Execution failed for task ':app:transformClassesWithDexForDebug'. java.lang.RuntimeException: java.util.concurrent.ExecutionException: org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdk1.8.0_60\bin\java.exe'' finished with non-zero exit value 1

well I fixed this with help of following steps:

  1. Open your app's build.gradle (not the one in the project root) and add:

    android {
    //add this into your existing 'android' block
        dexOptions {
        javaMaxHeapSize "4g"
  2. Try your build again.

Note: 4g is 4 Gigabytes and this is a maximum heap size for dex operation.

C# - Winforms - Global Variables

public static class MyGlobals
  public static string Global1 = "Hello";
  public static string Global2 = "World";

public class Foo

    private void Method1()
       string example = MyGlobals.Global1;

How to save an HTML5 Canvas as an image on a server?

Send canvas image to PHP:

var photo = canvas.toDataURL('image/jpeg');                
  method: 'POST',
  url: 'photo_upload.php',
  data: {
    photo: photo

Here's PHP script:


    $data = $_POST['photo'];
    list($type, $data) = explode(';', $data);
    list(, $data)      = explode(',', $data);
    $data = base64_decode($data);

    mkdir($_SERVER['DOCUMENT_ROOT'] . "/photos");

    file_put_contents($_SERVER['DOCUMENT_ROOT'] . "/photos/".time().'.png', $data);

Swift performSelector:withObject:afterDelay: is unavailable

Swift 4

DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
    // your function here

Swift 3

DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(0.1)) {
    // your function here

Swift 2

let dispatchTime: dispatch_time_t = dispatch_time(DISPATCH_TIME_NOW, Int64(0.1 * Double(NSEC_PER_SEC))) 
dispatch_after(dispatchTime, dispatch_get_main_queue(), { 
    // your function here 

How to get text from EditText?

The quickest solution to your problem I believe is that you simply are missing parentheses on your getText. Simply add () to edit.getText().toString() and that should solve it

get jquery `$(this)` id

Do you mean that for a select element with an id of "next" you need to perform some specific script?

    //enter code here

How to get datetime in JavaScript?

var now = new Date();

now.format("dd/MM/yyyy hh:mm TT");

Get full details here: Flagrant Badassery » JavaScript Date Format

SQL - How to select a row having a column with max value

Answer is to add a having clause:

SELECT [columns]
FROM table t1
WHERE value= (select max(value) from table)
AND date = (select MIN(date) from table t2 where t1.value = t2.value)

this should work and gets rid of the neccesity of having an extra sub select in the date clause.

Problem with converting int to string in Linq to entities

I ran into this same problem when I was converting my MVC 2 app to MVC 3 and just to give another (clean) solution to this problem I want to post what I did...

IEnumerable<SelectListItem> producers = new SelectList(Services.GetProducers(),
    "ID", "Name", model.ProducerID);

GetProducers() simply returns an entity collection of Producers. P.S. The SqlFunctions.StringConvert didn't work for me.

SASS and @font-face

For those looking for an SCSS mixin instead, including woff2:

@mixin fface($path, $family, $type: '', $weight: 400, $svg: '', $style: normal) {
  @font-face {
    font-family: $family;
    @if $svg == '' {
      // with OTF without SVG and EOT
      src: url('#{$path}#{$type}.otf') format('opentype'), url('#{$path}#{$type}.woff2') format('woff2'), url('#{$path}#{$type}.woff') format('woff'), url('#{$path}#{$type}.ttf') format('truetype');
    } @else {
      // traditional src inclusions
      src: url('#{$path}#{$type}.eot');
      src: url('#{$path}#{$type}.eot?#iefix') format('embedded-opentype'), url('#{$path}#{$type}.woff2') format('woff2'), url('#{$path}#{$type}.woff') format('woff'), url('#{$path}#{$type}.ttf') format('truetype'), url('#{$path}#{$type}.svg##{$svg}') format('svg');
    font-weight: $weight;
    font-style: $style;
// ========================================================importing
$dir: '/assets/fonts/';
$famatic: 'AmaticSC';
@include fface('#{$dir}amatic-sc-v11-latin-regular', $famatic, '', 400, $famatic);

$finter: 'Inter';
// adding specific types of font-weights
@include fface('#{$dir}#{$finter}', $finter, '-Thin-BETA', 100);
@include fface('#{$dir}#{$finter}', $finter, '-Regular', 400);
@include fface('#{$dir}#{$finter}', $finter, '-Medium', 500);
@include fface('#{$dir}#{$finter}', $finter, '-Bold', 700);
// ========================================================usage
.title {
  font-family: Inter;
  font-weight: 700; // Inter-Bold font is loaded
.special-title {
  font-family: AmaticSC;
  font-weight: 700; // default font is loaded

The $type parameter is useful for stacking related families with different weights.

The @if is due to the need of supporting the Inter font (similar to Roboto), which has OTF but doesn't have SVG and EOT types at this time.

If you get a can't resolve error, remember to double check your fonts directory ($dir).

How to implement and do OCR in a C# project?

Here's one: (check out or for more info)

using MODI;
static void Main(string[] args)
    DocumentClass myDoc = new DocumentClass();
    myDoc.Create(@"theDocumentName.tiff"); //we work with the .tiff extension
    myDoc.OCR(MiLANGUAGES.miLANG_ENGLISH, true, true);

    foreach (Image anImage in myDoc.Images)
        Console.WriteLine(anImage.Layout.Text); //here we cout to the console.

How do I get the Date & Time (VBS)

There are also separate Time() and Date() functions.

Change/Get check state of CheckBox

I know this is late info, but in jQuery, using .checked is possible and easy! If your element is something like:

    <input type="radio" name="bob" />

You can easily get/set checked state as such:

        var thisInput  = $(this).find("input[type=radio]");
        var checked =":checked");
        thisInput[0].checked = (checked) ?  false : true;

The secret is using the "[0]" array index identifier which is the ELEMENT of your jquery object! ENJOY!

How can I check if a string only contains letters in Python?

A pretty simple solution I came up with: (Python 3)

def only_letters(tested_string):
    for letter in tested_string:
        if letter not in "abcdefghijklmnopqrstuvwxyz":
            return False
    return True

You can add a space in the string you are checking against if you want spaces to be allowed.

Get current rowIndex of table in jQuery

Since "$(this).parent().index();" and "$(this).parent('table').index();" don't work for me, I use this code instead:

   var row_index = $(this).closest("tr").index();
   var col_index = $(this).index();

How to convert XML to JSON in Python?

I think the XML format can be so diverse that it's impossible to write a code that could do this without a very strict defined XML format. Here is what I mean:

        <name>Koen Bok</name>
        <name>Plutor Heidepeen</name>

Would become

{'persons': [
    {'name': 'Koen Bok', 'age': 26},
    {'name': 'Plutor Heidepeen', 'age': 33}]

But what would this be:

    <person name="Koen Bok">
        <locations name="defaults">
            <location long=123 lat=384 />

See what I mean?

Edit: just found this article:

What is Gradle in Android Studio?

In Android Studio, Gradle is used for building our android application projects, hence playing the role of a build system. Before Android Studio, in Eclipse we used to compile and build the applications using command line tool which was soon taken over by GUI based steps to build and run Android Applications in eclipse using ANT. Every android application development tool has to compile resources, java source code, external libraries and combine them into a final APK.

Gradle is a build system, which is responsible for code compilation, testing, deployment and conversion of the code into .dex files and hence running the app on the device.

As Android Studio comes with Gradle system pre-installed, there is no need to install additional runtime softwares to build our project. Whenever you click on Run button in android studio, a gradle task automatically triggers and starts building the project and after gradle completes its task, app starts running in AVD or in the connected device.

A build system like Gradle is not a compiler, linker etc, but it controls and supervises the operation of compilation, linking of files, running test cases, and eventually bundling the code into an apk file for your Android Application.

There are two build.gradle files for every android studio project of which, one is for application and other is for project level(module level) build files.

In the build process, the compiler takes the source code, resources, external libraries JAR files and AndroidManifest.xml(which contains the meta-data about the application) and convert them into .dex(Dalvik Executable files) files, which includes bytecode. That bytecode is supported by all android devices to run your app. Then APK Manager combines the .dex files and all other resources into single apk file. APK Packager signs debug or release apk using respective debug or release keystore.

Debug apk is generally used for testing purpose or we can say that it is used at development stage only. When your app is complete with desired features and you are ready to publish your application for external use then you require a Release apk signed using a release keystore.

Now lets shed some light on the gradle files.

setting.gradle The setting.gradle(Gradle setting) file is used to specify all the modules used in your app.

build.gradle (project level) The Top level (module) build.gradle file is project level build file, which defines build configurations at project level. This file applies configurations to all the modules in android application project.

build.gradle (application level) The Application level build.gradle file is located in each module of the android project. This file includes your package name as applicationID, version name(apk version), version code, minimum and target sdk for a specific application module. When you are including external libraries(not the jar files) then you need to mention it in the app level gradle file to include them in your project as dependencies of the application.

Note: If a certain application is developed in variations for individual modules like, Smart Phone, Tablet or TV then separate gradle files must to be created for all. You can even start your gradle system through command line tool. Following commands are used for it:

./gradlew build - (build project)
./gradlew clean build - (build project complete scratch)
./gradlew clean build - (run the test)
./gradlew wrapper - (to see all the available tasks)

How to reduce a huge excel file

i Change the format of file to *.XLSX this change compress my file and reduce file size of 15%

How to switch to new window in Selenium for Python?

for eg. you may take


since, it is a current window ,we can name it

main_page = driver.current_window_handle

if there are atleast 1 window popup except the current window,you may try this method and put if condition in break statement by hit n trial for the index

for handle in driver.window_handles:
    if handle != main_page:
        login_page = handle


Now ,whatever the credentials you have to apply,provide after it is loggen in. Window will disappear, but you have to come to main page window and you are done


Renaming files using node.js

You'll need to use fs for that:

And in particular the fs.rename() function:

var fs = require('fs');
fs.rename('/path/to/Afghanistan.png', '/path/to/AF.png', function(err) {
    if ( err ) console.log('ERROR: ' + err);

Put that in a loop over your freshly-read JSON object's keys and values, and you've got a batch renaming script.

fs.readFile('/path/to/countries.json', function(error, data) {
    if (error) {

    var obj = JSON.parse(data);
    for(var p in obj) {
        fs.rename('/path/to/' + obj[p] + '.png', '/path/to/' + p + '.png', function(err) {
            if ( err ) console.log('ERROR: ' + err);

(This assumes here that your .json file is trustworthy and that it's safe to use its keys and values directly in filenames. If that's not the case, be sure to escape those properly!)

PATH issue with pytest 'ImportError: No module named YadaYadaYada'

I was having the same problem when following the Flask tutorial and I found the answer on the official Pytest docs It's a little shift from the way I (and I think many others) are used to do things.

You have to create a file in your project's root directory with at least the following two lines:

from setuptools import setup, find_packages
setup(name="PACKAGENAME", packages=find_packages())

where PACKAGENAME is your app's name. Then you have to install it with pip:

pip install -e .

The -e flag tells pip to intall the package in editable or "develop" mode. So the next time you run pytest it should find your app in the standard PYTHONPATH.

ImportError: No module named pip


curl -o

Then run the following command in the folder where you downloaded:


How do I show the changes which have been staged?

By default git diff is used to show the changes which is not added to the list of git updated files. But if you want to show the changes which is added or stagged then you need to provide extra options that will let git know that you are interested in stagged or added files diff .

$ git diff          # Default Use
$ git diff --cached # Can be used to show difference after adding the files 
$ git diff --staged # Same as 'git diff --cached' mostly used with latest version of git 


$ git diff 
diff --git a/x/y/z.js  b/x/y/z.js index 98fc22b..0359d84 100644
--- a/x/y/z.js 
+++ b/x/y/z.js @@ -43,7 +43,7 @@ var a = function (tooltip) {

-        if (a)
+        if (typeof a !== 'undefined')
             res = 1;
             res = 2;

$ git add x/y/z.js
$ git diff

Once you added the files , you can't use default of 'git diff' .You have to do like this:-

$ git diff --cached
diff --git a/x/y/z.js  b/x/y/z.js index 98fc22b..0359d84 100644
    --- a/x/y/z.js 
    +++ b/x/y/z.js @@ -43,7 +43,7 @@ var a = function (tooltip) {

    -        if (a)
    +        if (typeof a !== 'undefined')
                 res = 1;
                 res = 2;

How can I calculate divide and modulo for integers in C#?

Division is performed using the / operator:

result = a / b;

Modulo division is done using the % operator:

result = a % b;

Cron job every three days

0 0 * * * [ $(($((date +%-j- 1)) % 3)) == 0 ] && script

Get the day of the year from date, offset by 1 to start at 0, check if it is modulo three.

Is arr.__len__() the preferred way to get the length of an array in Python?

len(list_name) function takes list as a parameter and it calls list's __len__() function.

Difference between and e.currentTarget

  • is element, which you f.e. click
  • e.currentTarget is element with added event listener.

If you click on child element of button, its better to use currentTarget to detect buttons attributes, in CH its sometimes problem to use

How do I get rid of an element's offset using CSS?

That offset is basically the x,y position that the browser has calculated for the element based on it's position css attribute. So if you put a <br> before it or any other element, it would change the offset. For example, you could set it to 0 by:




Therefore, whatever positioning issue you have, is not necessarily an issue with offset, though you could always fix it by playing with the top,left,right and bottom attributes.

Is your problem browser incompatibility?

Populating a dictionary using for loops (python)

dicts = {}
keys = range(4)
values = ["Hi", "I", "am", "John"]
for i in keys:
        dicts[i] = values[i]


In [7]: dict(list(enumerate(values)))
Out[7]: {0: 'Hi', 1: 'I', 2: 'am', 3: 'John'}

Creating a constant Dictionary in C#

I am not sure why no one mentioned this but in C# for things that I cannot assign const, I use static read-only properties.


public static readonly Dictionary<string, string[]> NewDictionary = new Dictionary<string, string[]>()
            { "Reference1", Array1 },
            { "Reference2", Array2 },
            { "Reference3", Array3 },
            { "Reference4", Array4 },
            { "Reference5", Array5 }

undefined reference to boost::system::system_category() when compiling

...and in case you wanted to link your main statically, in your Jamfile add the following to requirements:


and perhaps also:


AngularJS : ng-model binding not updating when changed with jQuery

I've written this little plugin for jQuery which will make all calls to .val(value) update the angular element if present:

(function($, ng) {
  'use strict';

  var $val = $.fn.val; // save original jQuery function

  // override jQuery function
  $.fn.val = function (value) {
    // if getter, just return original
    if (!arguments.length) {
      return $;

    // get result of original function
    var result = $, value);

    // trigger angular input (this[0] is the DOM object)

    // return the original result
    return result; 
})(window.jQuery, window.angular);

Just pop this script in after jQuery and angular.js and val(value) updates should now play nice.

Minified version:

!function(n,t){"use strict";var r=n.fn.val;n.fn.val=function(n){if(!arguments.length)return;var,n);return t.element(this[0]).triggerHandler("input"),e}}(window.jQuery,window.angular);


// the function_x000D_
(function($, ng) {_x000D_
  'use strict';_x000D_
  var $val = $.fn.val;_x000D_
  $.fn.val = function (value) {_x000D_
    if (!arguments.length) {_x000D_
      return $;_x000D_
    var result = $, value);_x000D_
    return result;_x000D_
})(window.jQuery, window.angular);_x000D_
(function(ng){ _x000D_
  ng.module('example', [])_x000D_
    .controller('ExampleController', function($scope) {_x000D_
      $scope.output = "output";_x000D_
      $scope.change = function() {_x000D_
        $scope.output = "" + $scope.input;_x000D_
(function($){  _x000D_
  $(function() {_x000D_
    var button = $('#button');_x000D_
    if (button.length)_x000D_
      console.log('hello, button');_x000D_
    _x000D_ {_x000D_
      var input = $('#input');_x000D_
      var value = parseInt(input.val());_x000D_
      value = isNaN(value) ? 0 : value;_x000D_
      input.val(value + 1);_x000D_
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<div ng-app="example" ng-controller="ExampleController">_x000D_
  <input type="number" id="input" ng-model="input" ng-change="change()" />_x000D_
  <button id="button">+</button>_x000D_

This answer was copied verbatim from my answer to another similar question.

jQuery form input select by id

You can just target the id directly:

var value = $('#b').val();

If you have more than one element with that id in the same page, it won't work properly anyway. You have to make sure that the id is unique.

If you actually are using the code for different pages, and only want to find the element on those pages where the id:s are nested, you can just use the descendant operator, i.e. space:

var value = $('#a #b').val(); Getting the error "Access to the path is denied." while trying to upload files to my Windows Server 2008 R2 Web server

Your account {MACHINE}\ASPNET does not have write access to that location. That is the reason why its failing.

Consider granting access rights to the resource to the ASP.NET request identity.

Right click on downloading folder Properties > Security Tab > Edit > Add > locations > choose your local machine > click OK > Type ASPNET below "Enter the object name to select" > Click Check Names Check the boxes for the desired access (Full Control). If it will not work for you do the same with Network Service

Now this should show your local {MACHINENAME}\ASPNET account, then you set the write permission to this account.

Otherwise if the application is impersonating via <identity impersonate="true"/>, the identity will be the anonymous user (typically IUSR_MACHINENAME) or the authenticated request user.

Or just use dedicated location for storing files in ASP.NET which is App_Data. To create it right click on your ASP.NET Project (in Visual Studio) Add > Add ASP.NET Folder > App_Data. Then you'll be able to save data to this location:

var path = Server.MapPath("~/App_Data/file.txt");
System.IO.File.WriteAllText(path, "Hello World");

Why use #ifndef CLASS_H and #define CLASS_H in .h file but not in .cpp?

The CLASS_H is an include guard; it's used to avoid the same header file being included multiple times (via different routes) within the same CPP file (or, more accurately, the same translation unit), which would lead to multiple-definition errors.

Include guards aren't needed on CPP files because, by definition, the contents of the CPP file are only read once.

You seem to have interpreted the include guards as having the same function as import statements in other languages (such as Java); that's not the case, however. The #include itself is roughly equivalent to the import in other languages.

Iterating C++ vector from the end to the beginning

template<class It>
std::reverse_iterator<It> reversed( It it ) {
  return std::reverse_iterator<It>(std::forward<It>(it));


for( auto rit = reversed(data.end()); rit != reversed(data.begin()); ++rit ) {
  std::cout << *rit;

Alternatively in C++14 just do:

for( auto rit = std::rbegin(data); rit != std::rend(data); ++rit ) {
  std::cout << *rit;

In C++03/11 most standard containers have a .rbegin() and .rend() method as well.

Finally, you can write the range adapter backwards as follows:

namespace adl_aux {
  using std::begin; using std::end;
  template<class C>
  decltype( begin( std::declval<C>() ) ) adl_begin( C&& c ) {
    return begin(std::forward<C>(c));
  template<class C>
  decltype( end( std::declval<C>() ) ) adl_end( C&& c ) {
    return end(std::forward<C>(c));

template<class It>
struct simple_range {
  It b_, e_;
  It begin() const { return b_; }
  It end() const { return e_; }
  simple_range( It b, It e ):b_(b), e_(e) {}

  template<class OtherRange>
  simple_range( OtherRange&& o ):
    simple_range(adl_aux::adl_begin(o), adl_aux::adl_end(o))

  // explicit defaults:
  simple_range( simple_range const& o ) = default;
  simple_range( simple_range && o ) = default;
  simple_range& operator=( simple_range const& o ) = default;
  simple_range& operator=( simple_range && o ) = default;
template<class C>
simple_range< decltype( reversed( adl_aux::adl_begin( std::declval<C&>() ) ) ) >
backwards( C&& c ) {
  return { reversed( adl_aux::adl_end(c) ), reversed( adl_aux::adl_begin(c) ) };

and now you can do this:

for (auto&& x : backwards(ctnr))
  std::cout << x;

which I think is quite pretty.

Appending a list to a list of lists in R

Just a note on Brian's answer below, the first assignment to outlist can also be an append statement so you could also do something like this:

resultsa <- list(1,2,3,4,5)
resultsb <- list(6,7,8,9,10)
resultsc <- list(11,12,13,14,15)

outlist <- list()
outlist <- append(outlist,list(resultsa))
outlist <- append(outlist, list(resultsb))
outlist <- append(outlist, list(resultsc))

This is sometimes helpful if you want to build a list from scratch in a loop.

Export to xls using angularjs

I had this problem and I made a tool to export an HTML table to CSV file. The problem I had with FileSaver.js is that this tool grabs the table with html format, this is why some people can't open the file in excel or google. All you have to do is export the js file and then call the function. This is the github url if someone has the same problem.

How to write to Console.Out during execution of an MSTest test

I found a solution of my own. I know that Andras answer is probably the most consistent with MSTEST, but I didn't feel like refactoring my code.

public void OneIsOne()
    using (ConsoleRedirector cr = new ConsoleRedirector())
        Assert.IsFalse(cr.ToString().Contains("New text"));
        /* call some method that writes "New text" to stdout */
        Assert.IsTrue(cr.ToString().Contains("New text"));

The disposable ConsoleRedirector is defined as:

internal class ConsoleRedirector : IDisposable
    private StringWriter _consoleOutput = new StringWriter();
    private TextWriter _originalConsoleOutput;
    public ConsoleRedirector()
        this._originalConsoleOutput = Console.Out;
    public void Dispose()
    public override string ToString()
        return this._consoleOutput.ToString();

How to create a connection string in c#

It occurs when IIS is not being connected to SQL SERVER. For a solution, see this screenshot: Solution

How to access static resources when mapping a global front controller servlet on /*

'Static' files in App Engine aren't directly accessible by your app. You either need to upload them twice, or serve the static files yourself, rather than using a static handler.

C# Copy a file to another location with a different name

You can use either File.Copy(oldFilePath, newFilePath) method or other way is, read file using StreamReader into an string and then use StreamWriter to write the file to destination location.

Your code might look like this :

StreamReader reader = new StreamReader("C:\foo.txt");
string fileContent = reader.ReadToEnd();

StreamWriter writer = new StreamWriter("D:\bar.txt");

You can add exception handling code...

How to use regex with find command?

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

Note that you need to specify .*/ in the beginning because find matches the whole path.


susam@nifty:~/so$ find . -name "*.jpg"
susam@nifty:~/so$ find . -regextype sed -regex ".*/[a-f0-9\-]\{36\}\.jpg"

My version of find:

$ find --version
find (GNU findutils) 4.4.2
Copyright (C) 2007 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Eric B. Decker, James Youngman, and Kevin Dalley.
Built using GNU gnulib version e5573b1bad88bfabcda181b9e0125fb0c52b7d3b
Features enabled: D_TYPE O_NOFOLLOW(enabled) LEAF_OPTIMISATION FTS() CBO(level=0) 
susam@nifty:~/so$ find . -regextype foo -regex ".*/[a-f0-9\-]\{36\}\.jpg"
find: Unknown regular expression type `foo'; valid types are `findutils-default', `awk', `egrep', `ed', `emacs', `gnu-awk', `grep', `posix-awk', `posix-basic', `posix-egrep', `posix-extended', `posix-minimal-basic', `sed'.

How do I set the size of an HTML text box?

Your markup:

<input type="text" class="resizedTextbox" />

The CSS:

.resizedTextbox {width: 100px; height: 20px}

Keep in mind that text box size is a "victim" of the W3C box model. What I mean by victim is that the height and width of a text box is the sum of the height/width properties assigned above, in addition to the padding height/width, and the border width. For this reason, your text boxes will be slightly different sizes in different browsers depending on the default padding in different browsers. Although different browsers tend to define different padding to text boxes, most reset style sheets don't tend to include <input /> tags in their reset sheets, so this is something to keep in mind.

You can standardize this by defining your own padding. Here is your CSS with specified padding, so the text box looks the same in all browsers:

.resizedTextbox {width: 100px; height: 20px; padding: 1px}

I added 1 pixel padding because some browsers tend to make the text box look too crammed if the padding is 0px. Depending on your design, you may want to add even more padding, but it is highly recommend you define the padding yourself, otherwise you'll be leaving it up to different browsers to decide for themselves. For even more consistency across browsers, you should also define the border yourself.

How can I get the average (mean) of selected columns

Here are some examples:

> z$mean <- rowMeans(subset(z, select = c(x, y)), na.rm = TRUE)
> z
  w x  y mean
1 5 1  1    1
2 6 2  2    2
3 7 3  3    3
4 8 4 NA    4

weighted mean

> z$y <- rev(z$y)
> z
  w x  y mean
1 5 1 NA    1
2 6 2  3    2
3 7 3  2    3
4 8 4  1    4
> weight <- c(1, 2) # x * 1/3 + y * 2/3
> z$wmean <- apply(subset(z, select = c(x, y)), 1, function(d) weighted.mean(d, weight, na.rm = TRUE))
> z
  w x  y mean    wmean
1 5 1 NA    1 1.000000
2 6 2  3    2 2.666667
3 7 3  2    3 2.333333
4 8 4  1    4 2.000000

Using the AND and NOT Operator in Python

You should write :

if (self.a != 0) and (self.b != 0) :

"&" is the bit wise operator and does not suit for boolean operations. The equivalent of "&&" is "and" in Python.

A shorter way to check what you want is to use the "in" operator :

if 0 not in (self.a, self.b) :

You can check if anything is part of a an iterable with "in", it works for :

  • Tuples. I.E : "foo" in ("foo", 1, c, etc) will return true
  • Lists. I.E : "foo" in ["foo", 1, c, etc] will return true
  • Strings. I.E : "a" in "ago" will return true
  • Dict. I.E : "foo" in {"foo" : "bar"} will return true

As an answer to the comments :

Yes, using "in" is slower since you are creating an Tuple object, but really performances are not an issue here, plus readability matters a lot in Python.

For the triangle check, it's easier to read :

0 not in (self.a, self.b, self.c)


(self.a != 0) and (self.b != 0) and (self.c != 0) 

It's easier to refactor too.

Of course, in this example, it really is not that important, it's very simple snippet. But this style leads to a Pythonic code, which leads to a happier programmer (and losing weight, improving sex life, etc.) on big programs.

MySQL dump by query

You could use --where option on mysqldump to produce an output that you are waiting for:

mysqldump -u root -p test t1 --where="1=1 limit 100" > arquivo.sql

At most 100 rows from test.t1 will be dumped from database table.

Cheers, WB

Convert a video to MP4 (H.264/AAC) with ffmpeg

Try This one:: Libav in Linux

Installation: run command  
               sudo apt-get install libav-tools 

Video conversion command::Go to folder contains the video and run in terminal
               avconv -i oldvideo.flv -ar 22050 convertedvideo.mp4

commandButton/commandLink/ajax action/listener method not invoked or input value not set/updated

Got stuck with this issue myself and found one more cause for this problem. If you don't have setter methods in your backing bean for the properties used in your *.xhtml , then the action is simply not invoked.

Stop jQuery .load response from being cached

Another approach to put the below line only when require to get data from server,Append the below line along with your ajax url.


Simple function to sort an array of objects

How about this?

var people = [
    name: 'a75',
    item1: false,
    item2: false
    name: 'z32',
    item1: true,
    item2: false
    name: 'e77',
    item1: false,
    item2: false

function sort_by_key(array, key)
 return array.sort(function(a, b)
  var x = a[key]; var y = b[key];
  return ((x < y) ? -1 : ((x > y) ? 1 : 0));

people = sort_by_key(people, 'name');

This allows you to specify the key by which you want to sort the array so that you are not limited to a hard-coded name sort. It will work to sort any array of objects that all share the property which is used as they key. I believe that is what you were looking for?

And here is a jsFiddle:

App installation failed due to application-identifier entitlement


  1. With your device connected, and Xcode open, select Window->Devices
  2. Now select the app and download the container using setting icon
  3. Delete the app
  4. Install app again using Xcode
  5. Stop from Xcode
  6. Go to Window->Device and select the app and replace the container that is backup from previous app

In MySQL, can I copy one row to insert into the same table?

For a very simple solution, you could use PHPMyAdmin to export the row as a CSV file then simply import the amended CSV file. Editing the ID/primarykey column to show a 0 for the primarykey value before you import it.

SELECT * FROM table where primarykey=1

Then at the bottom of the page:

enter image description here

Where is says "Export" simply export, then edit the csv file to remove the primarykey value, so it's empty, and then just import it into the database, a new primarykey will be assigned on import.

Convert from MySQL datetime to another format with PHP

You can have trouble with dates not returned in Unix Timestamp, so this works for me...

return date("F j, Y g:i a", strtotime(substr($datestring, 0, 15)))

How can I view live MySQL queries?

You can log every query to a log file really easily:

mysql> SHOW VARIABLES LIKE "general_log%";

| Variable_name    | Value                      |
| general_log      | OFF                        |
| general_log_file | /var/run/mysqld/mysqld.log |

mysql> SET GLOBAL general_log = 'ON';

Do your queries (on any db). Grep or otherwise examine /var/run/mysqld/mysqld.log

Then don't forget to

mysql> SET GLOBAL general_log = 'OFF';

or the performance will plummet and your disk will fill!

Get the previous month's first and last day dates in c#

DateTime now = DateTime.Now;
int prevMonth = now.AddMonths(-1).Month;
int year = now.AddMonths(-1).Year;
int daysInPrevMonth = DateTime.DaysInMonth(year, prevMonth);
DateTime firstDayPrevMonth = new DateTime(year, prevMonth, 1);
DateTime lastDayPrevMonth = new DateTime(year, prevMonth, daysInPrevMonth);
Console.WriteLine("{0} {1}", firstDayPrevMonth.ToShortDateString(),

In Java 8 how do I transform a Map<K,V> to another Map<K,V> using a lambda?

Here is another way that gives you access to the key and the value at the same time, in case you have to do some kind of transformation.

Map<String, Integer> pointsByName = new HashMap<>();
Map<String, Integer> maxPointsByName = new HashMap<>();

Map<String, Double> gradesByName = pointsByName.entrySet().stream()
        .map(entry -> new AbstractMap.SimpleImmutableEntry<>(
                entry.getKey(), ((double) entry.getValue() /
                        maxPointsByName.get(entry.getKey())) * 100d))
        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));

Which tool to build a simple web front-end to my database

The most rapid option is to hand out MS Access or SQL Sever Management Studio (there's a free express edition) along with a read only account.

PHP is simple and has a well earned reputation for getting stuff done. PHP is excellent for copying and pasting code, and you can iterate insanely fast in PHP. PHP can lead to hard-to-maintain applications, and it can be difficult to set up a visual debugger.

Given that you use SQL Server, ASP.NET is also a good option. This is somewhat harder to setup; you'll need an IIS server, with a configured application. Iterations are a bit slower. ASP.NET is easier to maintain and Visual Studio is the best visual debugger around.

How to get IP address of the device from code?

Based on what I have tested this is my proposal

import java.util.*;

public class hostUtil
   public static String HOST_NAME = null;
   public static String HOST_IPADDRESS = null;

   public static String getThisHostName ()
      if (HOST_NAME == null) obtainHostInfo ();
      return HOST_NAME;

   public static String getThisIpAddress ()
      if (HOST_IPADDRESS == null) obtainHostInfo ();
      return HOST_IPADDRESS;

   protected static void obtainHostInfo ()
      HOST_IPADDRESS = "";
      HOST_NAME = "localhost";

         InetAddress primera = InetAddress.getLocalHost();
         String hostname = InetAddress.getLocalHost().getHostName ();

         if (!primera.isLoopbackAddress () &&
             !hostname.equalsIgnoreCase ("localhost") &&
              primera.getHostAddress ().indexOf (':') == -1)
            // Got it without delay!!
            HOST_IPADDRESS = primera.getHostAddress ();
            HOST_NAME = hostname;
            //System.out.println ("First try! " + HOST_NAME + " IP " + HOST_IPADDRESS);
         for (Enumeration<NetworkInterface> netArr = NetworkInterface.getNetworkInterfaces(); netArr.hasMoreElements();)
            NetworkInterface netInte = netArr.nextElement ();
            for (Enumeration<InetAddress> addArr = netInte.getInetAddresses (); addArr.hasMoreElements ();)
               InetAddress laAdd = addArr.nextElement ();
               String ipstring = laAdd.getHostAddress ();
               String hostName = laAdd.getHostName ();

               if (laAdd.isLoopbackAddress()) continue;
               if (hostName.equalsIgnoreCase ("localhost")) continue;
               if (ipstring.indexOf (':') >= 0) continue;

               HOST_IPADDRESS = ipstring;
               HOST_NAME = hostName;
      } catch (Exception ex) {}

Spring cannot find bean xml configuration file when it does exist

Note that the first applicationContext is loaded as part of web.xml; which is mentioned with the below.



Where as below code will also tries to create one more applicationContext.

private static final ApplicationContext context = 
               new ClassPathXmlApplicationContext("beans.xml");

See the difference between beans.xml and applicationContext.xml

And if appliationContext.xml under <META-INF/spring/> has declared with <import resource="beans.xml"/> then this appliationContext.xml is loading the beans.xml under the same location META-INF/spring of appliationContext.xml.

Where as; in the code; if it is declared like below

ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");

This is looking the beans.xml at WEB-INF/classes OR in eclipse src/main/resources.

[If you have added beans.xml at src/main/resources then it might be placed at WEB-INF/classes while creating the WAR.]

So totally TWO files are looked up.

I have resolved this issue by adding classpath lookup while importing at applicationContext.xml like below

<import resource="classpath*:beans.xml" />

and removed the the line ClassPathXmlApplicationContext("beans.xml") in java code, so that there will be only one ApplicationContext loaded.

HTML.ActionLink method

Html.ActionLink(article.Title, "Login/" + article.ArticleID, 'Item") 

Go to next item in ForEach-Object

I know this is an old post, but I wanted to add something I learned for the next folks who land here while googling.

In Powershell 5.1, you want to use continue to move onto the next item in your loop. I tested with 6 items in an array, had a foreach loop through, but put an if statement with:

foreach($i in $array){    
    write-host -fore green "hello $i"
    if($i -like "something"){
        write-host -fore red "$i is bad"
        write-host -fore red "should not see this"

Of the 6 items, the 3rd one was something. As expected, it looped through the first 2, then the matching something gave me the red line where $i matched, I saw something is bad and then it went on to the next item in the array without saying should not see this. I tested with return and it exited the loop altogether.

Deleting records before a certain date

This helped me delete data based on different attributes. This is dangerous so make sure you back up database or the table before doing it:

mysqldump -h hotsname -u username -p password database_name > backup_folder/backup_filename.txt

Now you can perform the delete operation:

delete from table_name where column_name < DATE_SUB(NOW() , INTERVAL 1 DAY)

This will remove all the data from before one day. For deleting data from before 6 months:

delete from table_name where column_name < DATE_SUB(NOW() , INTERVAL 6 MONTH)

How to Diff between local uncommitted changes and origin

If you want to compare files visually you can use:

git difftool

It will start your diff app automatically for each changed file.

PS: If you did not set a diff app, you can do it like in the example below(I use Winmerge):

git config --global merge.tool winmerge
git config --replace --global mergetool.winmerge.cmd "\"C:\Program Files (x86)\WinMerge\WinMergeU.exe\" -e -u -dl \"Base\" -dr \"Mine\" \"$LOCAL\" \"$REMOTE\" \"$MERGED\""
git config --global mergetool.prompt false

Limit String Length

You can use something similar to the below:

if (strlen($str) > 10)
   $str = substr($str, 0, 7) . '...';

How to execute Python scripts in Windows?

Found an incredibly useful answer here: How to run different python versions in cmd?

I would suggest using the Python Launcher for Windows utility that introduced was into Python 3.3 a while ago. You can also manually download and install it directly from the author's website for use with earlier versions of Python 2 and 3.

Regardless of how you obtain it, after installation it will have associated itself with all the standard Python file extensions (i.e. .py, .pyw, .pyc, and .pyo files). You'll not only be able to explicitly control which version is used at the command-prompt, but also on a script-by-script basis by adding Linux/Unix-y shebang #!/usr/bin/env pythonX comments at the beginning of your Python scripts.

As J.F. Sebastian suggests, Python Launcher for Windows is the best and default choice for launching different version of Python in Windows. It used to be a third-party tool, but now it is officially supported since Python 3.3.

New in version 3.3.

The Python launcher for Windows is a utility which aids in the location and execution of different Python versions. It allows scripts (or the command-line) to indicate a preference for a specific Python version, and will locate and execute that version.

This is a great tool just use it!

Taking multiple inputs from user in python

You could use the below to take multiple inputs separated by a keyword

a,b,c=raw_input("Please enter the age of 3 people in one line using commas\n").split(',')

How To Remove Outline Border From Input Button

Focus outlines in Chrome and FF

enter image description here enter image description here


enter image description here

input[type="button"]::-moz-focus-inner {
   border: 0;


Accessibility (A11Y)

/* Don't forget! User accessibility is important */
input[type="button"]:focus {
  /* your custom focused styles here */

Attribute 'nowrap' is considered outdated. A newer construct is recommended. What is it?

If HTML and use bootstrap they have a helper class.

<span class="text-nowrap">1-866-566-7233</span>

How can I extract a number from a string in JavaScript?

You can extract numbers from a string using a regex expression:

let string = "xxfdx25y93.34xxd73";
let res = string.replace(/\D/g, "");

output: 25933473

ReactJS: setTimeout() not working?

You didn't tell who called setTimeout

Here how you call timeout without calling additional functions.

1. You can do this without making additional functions.

setTimeout(this.setState.bind(this, {position:1}), 3000);

Uses function.prototype.bind()

setTimeout takes the location of the function and keeps it in the context.

2. Another way to do the same even by writing even less code.

setTimeout(this.setState, 3000, {position:1});

Probably uses the same bind method at some point

The setTimeout only takes the location of the function and the function already has the context? Anyway, it works!

NOTE: These work with any function you use in js.

What does the keyword Set actually do in VBA?

set is used to assign a reference to an object. The C equivalent would be

 int i;
int* ref_i;

i = 4; // Assigning a value (in VBA: i = 4)
ref_i = &i; //assigning a reference (in VBA: set ref_i = i)