Programs & Examples On #Securitymanager

A security manager is an object that defines a security policy for an application. This policy specifies actions that are unsafe or sensitive. Any actions not allowed by the security policy cause a SecurityException to be thrown. An application can also query its security manager to discover which actions are allowed. Remote host closed connection during handshake during web service communicaiton

In my case, I got this problem because I had given the server a non-existent certificate, due to a typo in the config file. Instead of throwing an exception, the server proceeded like normal and sent an empty certificate to the client. So it might be worth checking to make sure that the server is providing the correct response.

I experienced this error while using the Jersey Client to connect to a server. The way I resolved it was by debugging the library and seeing that it actually did receive an EOF the moment it tried to read. I also tried connecting using a web browser and got the same results.

Just writing this here in case it ends up helping anyone.

java.lang.NoClassDefFoundError: javax/mail/Authenticator, whats wrong?

You need to add two jars into the WEB-INF/lib directory or your webapp (or lib directory of the server):

syntax error when using command line in python

In order to run scripts, you should write the "python" command in the command prompt, and not within the python shell. also, the file should be at the path you run from in the cli.

How to start automatic download of a file in Internet Explorer?

This is what I'm using in some sites (requires jQuery).:

$(document).ready(function() {
    var downloadUrl = "your_file_url";
    setTimeout("window.location.assign('" + downloadUrl + "');", 1000);

The file is downloaded automatically after 1 second.

Total size of the contents of all the files in a directory

Just an alternative:

ls -lAR | grep -v '^d' | awk '{total += $5} END {print "Total:", total}'

grep -v '^d' will exclude the directories.

Read XLSX file in Java

Apache POI 3.5 have added support to all the OOXML (docx, xlsx, etc.)

See the XSSF sub project

T-SQL STOP or ABORT command in SQL Server

An alternate solution could be to alter the flow of execution of your script by using the GOTO statement...

DECLARE  @RunScript bit;
SET @RunScript = 0;

IF @RunScript != 1
RAISERROR ('Raise Error does not stop processing, so we will call GOTO to skip over the script', 1, 1);
GOTO Skipper -- This will skip over the script and go to Skipper

PRINT 'This is where your working script can go';
PRINT 'This is where your working script can go';
PRINT 'This is where your working script can go';
PRINT 'This is where your working script can go';

Skipper: -- Don't do nuttin!

Warning! The above sample was derived from an example I got from Merrill Aldrich. Before you implement the GOTO statement blindly, I recommend you read his tutorial on Flow control in T-SQL Scripts.

In laymans terms, what does 'static' mean in Java?

static means that the variable or method marked as such is available at the class level. In other words, you don't need to create an instance of the class to access it.

public class Foo {
    public static void doStuff(){
        // does stuff

So, instead of creating an instance of Foo and then calling doStuff like this:

Foo f = new Foo();

You just call the method directly against the class, like so:


Selecting only first-level elements in jquery

Once you have the initial ul, you can use the children() method, which will only consider the immediate children of the element. As @activa points out, one way to easily select the root element is to give it a class or an id. The following assumes you have a root ul with id root.


Bash: infinite sleep (infinite blocking)

This approach will not consume any resources for keeping process alive.

while :; do sleep 1; done & kill -STOP $! && wait $!


  • while :; do sleep 1; done & Creates a dummy process in background
  • kill -STOP $! Stops the background process
  • wait $! Wait for the background process, this will be blocking forever, cause background process was stopped before

What's the difference between SHA and AES encryption?

SHA and AES serve different purposes. SHA is used to generate a hash of data and AES is used to encrypt data.

Here's an example of when an SHA hash is useful to you. Say you wanted to download a DVD ISO image of some Linux distro. This is a large file and sometimes things go wrong - so you want to validate that what you downloaded is correct. What you would do is go to a trusted source (such as the offical distro download point) and they typically have the SHA hash for the ISO image available. You can now generated the comparable SHA hash (using any number of open tools) for your downloaded data. You can now compare the two hashs to make sure they match - which would validate that the image you downloaded is correct. This is especially important if you get the ISO image from an untrusted source (such as a torrent) or if you are having trouble using the ISO and want to check if the image is corrupted.

As you can see in this case the SHA has was used to validate data that was not corrupted. You have every right to see the data in the ISO.

AES, on the other hand, is used to encrypt data, or prevent people from viewing that data with knowing some secret.

AES uses a shared key which means that the same key (or a related key) is used to encrypted the data as is used to decrypt the data. For example if I encrypted an email using AES and I sent that email to you then you and I would both need to know the shared key used to encrypt and decrypt the email. This is different than algorithms that use a public key such PGP or SSL.

If you wanted to put them together you could encrypt a message using AES and then send along an SHA1 hash of the unencrypted message so that when the message was decrypted they were able to validate the data. This is a somewhat contrived example.

If you want to know more about these some Wikipedia search terms (beyond AES and SHA) you want want to try include:

Symmetric-key algorithm (for AES) Cryptographic hash function (for SHA) Public-key cryptography (for PGP and SSL)

How do I use the nohup command without getting nohup.out?

If you have a BASH shell on your mac/linux in-front of you, you try out the below steps to understand the redirection practically :

Create a 2 line script called

echo "Hello. This is a proper command"
  • The echo command's output goes into STDOUT filestream (file descriptor 1).
  • The error command's output goes into STDERR filestream (file descriptor 2)

Currently, simply executing the script sends both STDOUT and STDERR to the screen.


Now start with the standard redirection : > zfile.txt

In the above, "echo" (STDOUT) goes into the zfile.txt. Whereas "error" (STDERR) is displayed on the screen.

The above is the same as : 1> zfile.txt

Now you can try the opposite, and redirect "error" STDERR into the file. The STDOUT from "echo" command goes to the screen. 2> zfile.txt

Combining the above two, you get: 1> zfile.txt 2>&1


  • FIRST, send STDOUT 1 to zfile.txt
  • THEN, send STDERR 2 to STDOUT 1 itself (by using &1 pointer).
  • Therefore, both 1 and 2 goes into the same file (zfile.txt)

Eventually, you can pack the whole thing inside nohup command & to run it in the background:

nohup 1> zfile.txt 2>&1&

How to remove duplicate objects in a List<MyObject> without equals/hashcode?

If your Blog class has an appropriate equals() method defined on it, the simplest way is just to create a Set out of your list, which will automatically remove duplicates:

List<Blog> blogList = ...; // your initial list
Set<Blog> noDups = new HashSet<Blog>(blogList)

The chances are this will work transparently with the rest of your code - if you're just iterating over the contents, for example, then any instance of Collection is as good as another. (If iteration order matters, then you may prefer a LinkedHashSet instead, which will preserve the original ordering of the list).

If you really need the result to be a List then keeping with the straightforward approach, you can just convert it straight back again by wrapping in an ArrayList (or similar). If your collections are relatively small (less than a thousand elements, say) then the apparent inefficiencies of this approach are likely to be immaterial.

What is a non-capturing group in regular expressions?

It makes the group non-capturing, which means that the substring matched by that group will not be included in the list of captures. An example in ruby to illustrate the difference:

"abc".match(/(.)(.)./).captures #=> ["a","b"]
"abc".match(/(?:.)(.)./).captures #=> ["b"]

Java Delegates?

Not really, no.

You may be able to achieve the same effect by using reflection to get Method objects you can then invoke, and the other way is to create an interface with a single 'invoke' or 'execute' method, and then instantiate them to call the method your interested in (i.e. using an anonymous inner class).

You might also find this article interesting / useful : A Java Programmer Looks at C# Delegates (

MySQL CONCAT returns NULL if any field contain NULL

Use CONCAT_WS instead:

CONCAT_WS() does not skip empty strings. However, it does skip any NULL values after the separator argument.

SELECT CONCAT_WS('-',`affiliate_name`,`model`,`ip`,`os_type`,`os_version`) AS device_name FROM devices

Read a file one line at a time in node.js?

You can always roll your own line reader. I have'nt benchmarked this snippet yet, but it correctly splits the incoming stream of chunks into lines without the trailing '\n'

var last = "";

process.stdin.on('data', function(chunk) {
    var lines, i;

    lines = (last+chunk).split("\n");
    for(i = 0; i < lines.length - 1; i++) {
        console.log("line: " + lines[i]);
    last = lines[i];

process.stdin.on('end', function() {
    console.log("line: " + last);


I did come up with this when working on a quick log parsing script that needed to accumulate data during the log parsing and I felt that it would nice to try doing this using js and node instead of using perl or bash.

Anyway, I do feel that small nodejs scripts should be self contained and not rely on third party modules so after reading all the answers to this question, each using various modules to handle line parsing, a 13 SLOC native nodejs solution might be of interest .

Getting the parent of a directory in Bash

Depending on whether you need absolute paths you may want to take an extra step:

parent=$(dirname "$child")
abs_parent=$(realpath "$parent")

C# - Substring: index and length must refer to a location within the string

Try This:

 int positionOfJPG=url.IndexOf(".jpg");
 string newString = url.Substring(18, url.Length - positionOfJPG);

How do you setLayoutParams() for an ImageView?

If you're changing the layout of an existing ImageView, you should be able to simply get the current LayoutParams, change the width/height, and set it back:

android.view.ViewGroup.LayoutParams layoutParams = myImageView.getLayoutParams();
layoutParams.width = 30;
layoutParams.height = 30;

I don't know if that's your goal, but if it is, this is probably the easiest solution.

The remote host closed the connection. The error code is 0x800704CD

I got this error when I dynamically read data from a WebRequest and never closed the Response.

    protected System.IO.Stream GetStream(string url)
            System.IO.Stream stream = null;
            var request = System.Net.WebRequest.Create(url);
            var response = request.GetResponse();

            if (response != null) {
                stream = response.GetResponseStream();

                // I never closed the response thus resulting in the error
            response = null;
            request = null;

            return stream;
        catch (Exception) { }
        return null;

jQuery add blank option to top of list and make selected to existing dropdown

This worked:

$("#theSelectId").prepend("<option value='' selected='selected'></option>");

Firebug Output:

<select id="theSelectId">
  <option selected="selected" value=""/>
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="mercedes">Mercedes</option>
  <option value="audi">Audi</option>

You could also use .prependTo if you wanted to reverse the order:

?$("<option>", { value: '', selected: true }).prependTo("#theSelectId");???????????

Excluding Maven dependencies

Global exclusions look like they're being worked on, but until then...

From the Sonatype maven reference (bottom of the page):

Dependency management in a top-level POM is different from just defining a dependency on a widely shared parent POM. For starters, all dependencies are inherited. If mysql-connector-java were listed as a dependency of the top-level parent project, every single project in the hierarchy would have a reference to this dependency. Instead of adding in unnecessary dependencies, using dependencyManagement allows you to consolidate and centralize the management of dependency versions without adding dependencies which are inherited by all children. In other words, the dependencyManagement element is equivalent to an environment variable which allows you to declare a dependency anywhere below a project without specifying a version number.

As an example:


It doesn't make the code less verbose overall, but it does make it less verbose where it counts. If you still want it less verbose you can follow these tips also from the Sonatype reference.

How do I get the value of text input field using JavaScript?

I would create a variable to store the input like this:

var input = document.getElementById("input_id").value;

And then I would just use the variable to add the input value to the string.

= "Your string" + input;

Real differences between "java -server" and "java -client"?

Oracle’s online documentation provides some information for Java SE 7.

On the java – the Java application launcher page for Windows, the -client option is ignored in a 64-bit JDK:

Select the Java HotSpot Client VM. A 64-bit capable jdk currently ignores this option and instead uses the Java HotSpot Server VM.

However (to make things interesting), under -server it states:

Select the Java HotSpot Server VM. On a 64-bit capable jdk only the Java HotSpot Server VM is supported so the -server option is implicit. This is subject to change in a future release.

The Server-Class Machine Detection page gives information on which VM is selected by OS and architecture.

I don’t know how much of this applies to JDK 6.

Can't change z-index with JQuery


How to trigger a build only if changes happen on particular set of files

If the logic for choosing the files is not trivial, I would trigger script execution on each change and then write a script to check if indeed a build is required, then triggering a build if it is.

Hide div after a few seconds

There's a really simple way to do this.

The problem is that .delay only effects animations, so what you need to do is make .hide() act like an animation by giving it a duration.


By giving it a nice short duration, it appears to be instant just like the regular .hide function.

Download image from the site in .NET/C#

You can use this code

using (WebClient client = new WebClient()) {
                    Stream stream = client.OpenRead(imgUrl);
                    if (stream != null) {
                        Bitmap bitmap = new Bitmap(stream);
                        ImageFormat imageFormat = ImageFormat.Jpeg;
                        if (bitmap.RawFormat.Equals(ImageFormat.Png)) {
                            imageFormat = ImageFormat.Png;
                        else if (bitmap.RawFormat.Equals(ImageFormat.Bmp)) {
                            imageFormat = ImageFormat.Bmp;
                        else if (bitmap.RawFormat.Equals(ImageFormat.Gif)) {
                            imageFormat = ImageFormat.Gif;
                        else if (bitmap.RawFormat.Equals(ImageFormat.Tiff)) {
                            imageFormat = ImageFormat.Tiff;

                        bitmap.Save(fileName, imageFormat);

Project available at: github

Send response to all clients except sender

Here is a more complete answer about what has changed from 0.9.x to 1.x.

 // send to current request socket client
 socket.emit('message', "this is a test");// Hasn't changed

 // sending to all clients, include sender
 io.sockets.emit('message', "this is a test"); // Old way, still compatible
 io.emit('message', 'this is a test');// New way, works only in 1.x

 // sending to all clients except sender
 socket.broadcast.emit('message', "this is a test");// Hasn't changed

 // sending to all clients in 'game' room(channel) except sender'game').emit('message', 'nice game');// Hasn't changed

 // sending to all clients in 'game' room(channel), include sender'game').emit('message', 'cool game');// Old way, DOES NOT WORK ANYMORE'game').emit('message', 'cool game');// New way'game').emit('message', 'cool game');// New way, "in" or "to" are the exact same: "And then simply use to or in (they are the same) when broadcasting or emitting:" from

 // sending to individual socketid, socketid is like a room
 io.sockets.socket(socketid).emit('message', 'for your eyes only');// Old way, DOES NOT WORK ANYMORE'message', 'for your eyes only');// New way

I wanted to edit the post of @soyuka but my edit was rejected by peer-review.

Printing an array in C++?

// Just do this, use a vector with this code and you're good lol -Daniel

#include <Windows.h>
#include <iostream>
#include <vector>

using namespace std;

int main()

    std::vector<const char*> arry = { "Item 0","Item 1","Item 2","Item 3" ,"Item 4","Yay we at the end of the array"};
    if (arry.size() != arry.size() || arry.empty()) {
        printf("what happened to the array lol\n ");
    for (int i = 0; i < arry.size(); i++)
        if (arry.max_size() == true) {
            cout << "Max size of array reached!";
        cout << "Array Value " << i << " = " << << endl;

Facebook Open Graph not clearing cache

Yes, facebook automatically clears the cache every 24 hours: Actually facebook scrapes the pages and updates the cache every 24 hours

Finding an elements XPath using IE Developer tool

If your goal is to find CSS selectors you can use MRI (once MRI is open, click any element to see various selectors for the element):

For Xpath:

How do I get column names to print in this C# program?

foreach (DataRow row in dt.Rows)
    foreach (DataColumn column in dt.Columns)
        ColumnName = column.ColumnName;
        ColumnData = row[column].ToString();

Javascript AES encryption

In my searches for AES encryption i found this from some Standford students. Claims to be fastest out there. Supports CCM, OCB, GCM and Block encryption.

Failed to load resource: the server responded with a status of 404 (Not Found) error in server

Use your browser's network inspector (F12) to see when the browser is requesting the bgbody.png image and what absolute path it's using and why the server is returning a 404 response.

...assuming that bgbody.png actually exists :)

Is your CSS in a stylesheet file or in a <style> block in a page? If it's in a stylesheet then the relative path must be relative to the CSS stylesheet (not the document that references it). If it's in a page then it must be relative to the current resource path. If you're using non-filesystem-based resource paths (i.e. using URL rewriting or URL routing) then this will cause problems and it's best to always use absolute paths.

Going by your relative path it looks like you store your images separately from your stylesheets. I don't think this is a good idea - I support storing images and other resources, like fonts, in the same directory as the stylesheet itself, as it simplifies paths and is also a more logical filesystem arrangement.

Can we open pdf file using UIWebView on iOS?

Swift version:

if let docPath = NSBundle.mainBundle().pathForResource("sample", ofType: "pdf") {
    let docURL = NSURL(fileURLWithPath: docPath)
    webView.loadRequest(NSURLRequest(URL: docURL))

Stop Chrome Caching My JS Files

A few ideas:

  1. When you refresh your page in Chrome, do a CTRL+F5 to do a full refresh.
  2. Even if you set the expires to 0, it will still cache during the session. You'll have to close and re-open your browser again.
  3. Make sure when you save the files on the server, the timestamps are getting updated. Chrome will first issue a HEAD command instead of a full GET to see if it needs to download the full file again, and the server uses the timestamp to see.

If you want to disable caching on your server, you can do something like:

Header set Expires "Thu, 19 Nov 1981 08:52:00 GM"
Header set Cache-Control "no-store, no-cache, must-revalidate, post-check=0, pre-check=0"
Header set Pragma "no-cache"

In .htaccess

How does the class_weight parameter in scikit-learn work?

First off, it might not be good to just go by recall alone. You can simply achieve a recall of 100% by classifying everything as the positive class. I usually suggest using AUC for selecting parameters, and then finding a threshold for the operating point (say a given precision level) that you are interested in.

For how class_weight works: It penalizes mistakes in samples of class[i] with class_weight[i] instead of 1. So higher class-weight means you want to put more emphasis on a class. From what you say it seems class 0 is 19 times more frequent than class 1. So you should increase the class_weight of class 1 relative to class 0, say {0:.1, 1:.9}. If the class_weight doesn't sum to 1, it will basically change the regularization parameter.

For how class_weight="auto" works, you can have a look at this discussion. In the dev version you can use class_weight="balanced", which is easier to understand: it basically means replicating the smaller class until you have as many samples as in the larger one, but in an implicit way.

Address in mailbox given [] does not comply with RFC 2822, 3.6.2. when email is in a variable

Its because the email address which is being sent is blank. see those empty brackets? that means the email address is not being put in the $address of the swiftmailer function.

Import Google Play Services library in Android Studio






How do I change the JAVA_HOME for ant?

JAVA_HOME should point at where the JDK is installed not not a JRE.

So, if you type ls $JAVA_HOME what do you see? if you do ls $JAVA_HOME/bin/ do you see javac?

If the first doesn't work then you don't have JAVA_HOME pointing at the right directory. If the second doesn't work then you need to point JAVA_HOME at a JDK instead of a JRE.

How do I remove all non-ASCII characters with regex and Notepad++?

This expression will search for non-ASCII values:


Tick off 'Search Mode = Regular expression', and click Find Next.

Source: Regex any ASCII character

Rownum in postgresql

I have just tested in Postgres 9.1 a solution which is close to Oracle ROWNUM:

select row_number() over() as id, t.*
from information_schema.tables t;

Rollback a Git merge

Reverting a merge commit has been exhaustively covered in other questions. When you do a fast-forward merge, the second one you describe, you can use git reset to get back to the previous state:

git reset --hard <commit_before_merge>

You can find the <commit_before_merge> with git reflog, git log, or, if you're feeling the moxy (and haven't done anything else): git reset --hard HEAD@{1}

Are there inline functions in java?

Java does not provide a way to manually suggest that a method should be inlined. As @notnoop says in the comments, the inlining is typically done by the JVM at execution time.

How to change active class while click to another link in bootstrap use jquery?

You are binding you click on the wrong element, you should bind it to the a.

You are prevent default event to occur on the li, but li have no default behavior, a does.

Try this:

$(document).ready(function () {
    $('.nav li a').click(function(e) {


        var $parent = $(this).parent();

How to use confirm using sweet alert?

    title: 'Are you sure?',
    text: "You won't be able to revert this!",
    type: 'warning',
    showCancelButton: true,
    confirmButtonColor: '#3085d6',
    cancelButtonColor: '#d33',
    confirmButtonText: 'Confirm!'
    alert("The confirm button was clicked");
    alert("The alert was dismissed by the user: "+reason);

How can I record a Video in my Android App.?

Here is a simple video recording example using the MediaRecorder:

public class VideoCapture extends Activity implements OnClickListener, SurfaceHolder.Callback {
    MediaRecorder recorder;
    SurfaceHolder holder;
    boolean recording = false;
    public void onCreate(Bundle savedInstanceState) {

        recorder = new MediaRecorder();

        SurfaceView cameraView = (SurfaceView) findViewById(;
        holder = cameraView.getHolder();


    private void initRecorder() {

        CamcorderProfile cpHigh = CamcorderProfile
        recorder.setMaxDuration(50000); // 50 seconds
        recorder.setMaxFileSize(5000000); // Approximately 5 megabytes

    private void prepareRecorder() {

        try {
        } catch (IllegalStateException e) {
        } catch (IOException e) {

    public void onClick(View v) {
        if (recording) {
            recording = false;

            // Let's initRecorder so we can record again
        } else {
            recording = true;

    public void surfaceCreated(SurfaceHolder holder) {

    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {

    public void surfaceDestroyed(SurfaceHolder holder) {
        if (recording) {
            recording = false;

It's from my book: Pro Android Media: Developing Graphics, Music, Video, and Rich Media Apps for Smartphones and Tablets

Also, do not forget to include these permissions in manifest:

<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

How to get logged-in user's name in Access vba?

Public Declare Function GetUserName Lib "advapi32.dll" 
    Alias "GetUserNameA" (ByVal lpBuffer As String, nSize As Long) As Long


Dim strLen As Long
Dim strtmp As String * 256
Dim strUserName As String

strLen = 255
GetUserName strtmp, strLen
strUserName = Trim$(TrimNull(strtmp))

Turns out question has been asked before: How can I get the currently logged-in windows user in Access VBA?

How can I draw circle through XML Drawable - Android?

no need for the padding or the corners.

here's a sample:

<shape xmlns:android="" android:shape="oval" >
    <gradient android:startColor="#FFFF0000" android:endColor="#80FF00FF"

based on :

Why can't I display a pound (£) symbol in HTML?

You need to save your PHP script file in UTF-8 encoding, and leave the <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> in the HTML.

For text editor, I recommend Notepad++, because it can detect and display the actual encoding of the file (in the lower right corner of the editor), and you can convert it as well.

error: resource android:attr/fontVariationSettings not found

after upgrading to Android 3.4.2 and FTC SDK5.2. I got these errors when building APK:

Android resource linking failed C:\Users\idsid\FTC\SkyStone\TeamCode\build\intermediates\incremental\mergeDebugResources\merged.dir\values\values.xml:1205: error: resource android:attr/fontVariationSettings not found. C:\Users\idsid\FTC\SkyStone\TeamCode\build\intermediates\incremental\mergeDebugResources\merged.dir\values\values.xml:1206: error: resource android:attr/ttcIndex not found. error: failed linking references.

What I did is to add following section to project build gradle and problem is fixed.

subprojects {
    afterEvaluate {project ->
        if (project.hasProperty("android")) {
            android {
                compileSdkVersion 28
                buildToolsVersion '29.0.2'

Good luck.

Remove a git commit which has not been pushed

This is what I do:

First checkout your branch (for my case master branch):

git checkout master

Then reset to remote HEAD^ (it'll remove all your local changes), force clean and pull:

git reset HEAD^ --hard && git clean -df && git pull

Undefined symbols for architecture i386

At the risk of sounding obvious, always check the spelling of your forward class files. Sometimes XCode (at least XCode 4.3.2) will turn a declaration green that's actually camel cased incorrectly. Like in this example:

"_OBJC_CLASS_$_RadioKit", referenced from:
  objc-class-ref in RadioPlayerViewController.o

If RadioKit was a class file and you make it a property of another file, in the interface declaration, you might see that

Radiokit *rk;

has "Radiokit" in green when the actual decalaration should be:

RadioKit *rk;

This error will also throw this type of error. Another example (in my case), is when you have _iPhone and _iphone extensions on your class names for universal apps. Once I changed the appropriate file from _iphone to the correct _iPhone, the errors went away.

Convert base64 png data to javascript file objects

You can create a Blob from your base64 data, and then read it asDataURL:

var img_b64 = canvas.toDataURL('image/png');
var png = img_b64.split(',')[1];

var the_file = new Blob([window.atob(png)],  {type: 'image/png', encoding: 'utf-8'});

var fr = new FileReader();
fr.onload = function ( oFREvent ) {
    var v =',')[1]; // encoding is messed up here, so we fix it
    v = atob(v);
    var good_b64 = btoa(decodeURIComponent(escape(v)));
    document.getElementById("uploadPreview").src = "data:image/png;base64," + good_b64;

Full example (includes junk code and console log):

Alternatively, you can use .readAsText, it works fine, and its more elegant.. but for some reason text does not sound right ;)

fr.onload = function ( oFREvent ) {
    document.getElementById("uploadPreview").src = "data:image/png;base64,"
    + btoa(;
fr.readAsText(the_file, "utf-8"); // its important to specify encoding here

Full example:

How to figure out the SMTP server host?

Email tech support at your client's hosting provider and ask for the information.

Converting java.sql.Date to java.util.Date

From reading the source code, if a java.sql.Date does actually have time information, calling getTime() will return a value that includes the time information.

If that is not working, then the information is not in the java.sql.Date object. I expect that the JDBC drivers or the database is (in effect) zeroing the time component ... or the information wasn't there in the first place.

I think you should be using java.sql.Timestamp and the corresponding resultset methods, and the corresponding SQL type.

How to fix 'Notice: Undefined index:' in PHP form action

Please try this

error_reporting = E_ALL & ~E_NOTICE

in php.ini

Cannot find JavaScriptSerializer in .Net 4.0

Just so you know, I am using Visual Studio 2013 and have had the same problem until I used the Project Properties to switch to 3.5 framework and back to 4.5. This for some reason registered the .dll properly and I could use the System.Web.Extensions.

enter image description here

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How to use a WSDL file to create a WCF service (not make a call)

There are good resources out there if you know what to search for. Try "Contract First" and WCF. or "WSDL First" and WCF.

Here is a selection:

Column order manipulation using col-lg-push and col-lg-pull in Twitter Bootstrap 3

Misconception Common misconception with column ordering is that, I should (or could) do the pushing and pulling on mobile devices, and that the desktop views should render in the natural order of the markup. This is wrong.

Reality Bootstrap is a mobile first framework. This means that the order of the columns in your HTML markup should represent the order in which you want them displayed on mobile devices. This mean that the pushing and pulling is done on the larger desktop views. not on mobile devices view..

Brandon Schmalz - Full Stack Web Developer Have a look at full description here

Use CSS to make a span not clickable

Yes you can.... you can place something on top of the link element.

<!DOCTYPE html>
    <title>Yes you CAN</title>
    <style type="text/css">
            width: 500px;
            border: 5px solid black; 
        .product-type-simple {
            position: relative;
            height: 150px;
            width: 150px;
            position: absolute;
            height: 100% ;
            width: 100% ;
            content: '';
            background: green;//for debugging purposes , remove this if you want to see whats behind
            z-index: 999999999999;
    <li class='product-type-simple'>
        <a href="/link1">
            <img src="">
    <li class='product-type-simple'>
        <a href="/link2">
            <img src="">

the magic sauce happens at product-type-simple:before class Whats happening here is that for each element that has class of product-type-simple you create something that has the width and height equal to that of the product-type-simple , then you increase its z-index to make sure it will place it self on top of the content of product-type-simple. You can toggle the background color if you want to see whats going on.

here is an example of the code

WCF timeout exception detailed investigation

I've just solved the problem.I found that the nodes in the App.config file have configed wrong.

<endpoint name="WCF_QtrwiseSalesService" binding="wsHttpBinding" bindingConfiguration="ws" address="http://cntgbs1131:9005/MyService/TGE.ISupplierClientManager" contract="*">

        <binding name="ws" maxBufferPoolSize="2147483647" maxReceivedMessageSize="2147483647" messageEncoding="Text">
            <readerQuotas maxDepth="2147483647" maxStringContentLength="2147483647" maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647"/>
            <**security mode="None">**
                <transport clientCredentialType="None"></transport>

Confirm your config in the node <security>,the attribute "mode" value is "None". If your value is "Transport",the error occurs.

How to convert SecureString to System.String?

In my opinion, extension methods are the most comfortable way to solve this.

I took Steve in CO's excellent answer and put it into an extension class as follows, together with a second method I added to support the other direction (string -> secure string) as well, so you can create a secure string and convert it into a normal string afterwards:

public static class Extensions
    // convert a secure string into a normal plain text string
    public static String ToPlainString(this System.Security.SecureString secureStr)
        String plainStr=new System.Net.NetworkCredential(string.Empty, secureStr).Password;
        return plainStr;

    // convert a plain text string into a secure string
    public static System.Security.SecureString ToSecureString(this String plainStr)
        var secStr = new System.Security.SecureString(); secStr.Clear();
        foreach (char c in plainStr.ToCharArray())
        return secStr;

With this, you can now simply convert your strings back and forth like so:

// create a secure string
System.Security.SecureString securePassword = "MyCleverPwd123".ToSecureString(); 
// convert it back to plain text
String plainPassword = securePassword.ToPlainString();  // convert back to normal string

But keep in mind the decoding method should only be used for testing.

How to change UINavigationBar background color from the AppDelegate

Swift syntax:

    UINavigationBar.appearance().barTintColor = UIColor.whiteColor() //changes the Bar Tint Color

I just put that in the AppDelegate didFinishLaunchingWithOptions and it persists throughout the app

C# Passing Function as Argument

Using the Func as mentioned above works but there are also delegates that do the same task and also define intent within the naming:

public delegate double MyFunction(double x);

public double Diff(double x, MyFunction f)
    double h = 0.0000001;

    return (f(x + h) - f(x)) / h;

public double MyFunctionMethod(double x)
    // Can add more complicated logic here
    return x + 10;

public void Client()
    double result = Diff(1.234, x => x * 456.1234);
    double secondResult = Diff(2.345, MyFunctionMethod);

How to recover Git objects damaged by hard disk failure?

In some previous backups, your bad objects may have been packed in different files or may be loose objects yet. So your objects may be recovered.

It seems there are a few bad objects in your database. So you could do it the manual way.

Because of git hash-object, git mktree and git commit-tree do not write the objects because they are found in the pack, then start doing this:

mv .git/objects/pack/* <somewhere>
for i in <somewhere>/*.pack; do
  git unpack-objects -r < $i
rm <somewhere>/*

(Your packs are moved out from the repository, and unpacked again in it; only the good objects are now in the database)

You can do:

git cat-file -t 6c8cae4994b5ec7891ccb1527d30634997a978ee

and check the type of the object.

If the type is blob: retrieve the contents of the file from previous backups (with git show or git cat-file or git unpack-file; then you may git hash-object -w to rewrite the object in your current repository.

If the type is tree: you could use git ls-tree to recover the tree from previous backups; then git mktree to write it again in your current repository.

If the type is commit: the same with git show, git cat-file and git commit-tree.

Of course, I would backup your original working copy before starting this process.

Also, take a look at How to Recover Corrupted Blob Object.

Image Processing: Algorithm Improvement for 'Coca-Cola Can' Recognition

I'm not aware of OpenCV but looking at the problem logically I think you could differentiate between bottle and can by changing the image which you are looking for i.e. Coca Cola. You should incorporate till top portion of can as in case of can there is silver lining at top of coca cola and in case of bottle there will be no such silver lining.

But obviously this algorithm will fail in cases where top of can is hidden, but in such case even human will not be able to differentiate between the two (if only coca cola portion of bottle/can is visible)

how to clear JTable

Basically, it depends on the TableModel that you are using for your JTable. If you are using the DefaultTableModel then you can do it in two ways:

DefaultTableModel dm = (DefaultTableModel)table.getModel();
dm.fireTableDataChanged(); // notifies the JTable that the model has changed


DefaultTableModel dm = (DefaultTableModel)table.getModel();
while(dm.getRowCount() > 0)

See the JavaDoc of DefaultTableModel for more details

How do I protect javascript files?

From my knowledge, this is not possible.

Your browser has to have access to JS files to be able to execute them. If the browser has access, then browser's user also has access.

If you password protect your JS files, then the browser won't be able to access them, defeating the purpose of having JS in the first place.

"unrecognized selector sent to instance" error in Objective-C

In my case, in iOS 13, I only had to implement the whole function and selector calling parts put in to main thread.

Calculate last day of month in JavaScript

A slight modification to solution provided by lebreeze:

function daysInMonth(iMonth, iYear)
    return new Date(iYear, iMonth, 0).getDate();

How to enable core dump in my Linux C++ program

By default many profiles are defaulted to 0 core file size because the average user doesn't know what to do with them.

Try ulimit -c unlimited before running your program.

jQuery count child elements

You can use .length with just a descendant selector, like this:

var count = $("#selected li").length;

If you have to use .children(), then it's like this:

var count = $("#selected ul").children().length;

You can test both versions here.

Wrapping a react-router Link in an html button

Update for React Router version 6:

The various answers here are like a timeline of react-router's evolution

Using the latest hooks from react-router v6, this can now be done easily with the useNavigate hook.

import { useNavigate } from 'react-router-dom'      

function MyLinkButton() {
  const navigate = useNavigate()
  return (
      <button onClick={() => navigate("/home")}>
        Go Home

What is the difference between pull and clone in git?

git clone is used for just downloading exactly what is currently working on the remote server repository and saving it in your machine's folder where that project is placed. Mostly it is used only when we are going to upload the project for the first time. After that pull is the better option.

git pull is basically a (clone(download) + merge) operation and mostly used when you are working as teamwork. In other words, when you want the recent changes in that project, you can pull.

Reasons for using the set.seed function

set.seed is a base function that it is able to generate (every time you want) together other functions (rnorm, runif, sample) the same random value.

Below an example without set.seed

> set.seed(NULL)
> rnorm(5)
[1]  1.5982677 -2.2572974  2.3057461  0.5935456  0.1143519
> rnorm(5)
[1]  0.15135371  0.20266228  0.95084266  0.09319339 -1.11049182
> set.seed(NULL)
> runif(5)
[1] 0.05697712 0.31892399 0.92547023 0.88360393 0.90015169
> runif(5)
[1] 0.09374559 0.64406494 0.65817582 0.30179009 0.19760375
> set.seed(NULL)
> sample(5)
[1] 5 4 3 1 2
> sample(5)
[1] 2 1 5 4 3

Below an example with set.seed

> set.seed(123)
> rnorm(5)
[1] -0.56047565 -0.23017749  1.55870831  0.07050839  0.12928774
> set.seed(123)
> rnorm(5)
[1] -0.56047565 -0.23017749  1.55870831  0.07050839  0.12928774
> set.seed(123)
> runif(5)
[1] 0.2875775 0.7883051 0.4089769 0.8830174 0.9404673
> set.seed(123)
> runif(5)
[1] 0.2875775 0.7883051 0.4089769 0.8830174 0.9404673
> set.seed(123)
> sample(5)
[1] 3 2 5 4 1
> set.seed(123)
> sample(5)
[1] 3 2 5 4 1

How to represent the double quotes character (") in regex?

Firstly, double quote character is nothing special in regex - it's just another character, so it doesn't need escaping from the perspective of regex.

However, because java uses double quotes to delimit String constants, if you want to create a string in java with a double quote in it, you must escape them.

This code will test if your String matches:

if (str.matches("\".*\"")) {
    // this string starts and end with a double quote

Note that you don't need to add start and end of input markers (^ and $) in the regex, because matches() requires that the whole input be matched to return true - ^ and $ are implied.

How to solve time out in phpmyadmin?

If using Cpanel/WHM the location of file config.default.php is under


and you should change the $cfg['ExecTimeLimit'] = 300; to $cfg['ExecTimeLimit'] = 0;

How to create custom config section in app.config?

Import namespace :

using System.Configuration;

Create ConfigurationElement Company :

public class Company : ConfigurationElement

        [ConfigurationProperty("name", IsRequired = true)]
        public string Name
                return this["name"] as string;
            [ConfigurationProperty("code", IsRequired = true)]
        public string Code
                return this["code"] as string;


public class Companies
        : ConfigurationElementCollection
        public Company this[int index]
                return base.BaseGet(index) as Company ;
                if (base.BaseGet(index) != null)
                this.BaseAdd(index, value);

       public new Company this[string responseString]
            get { return (Company) BaseGet(responseString); }
                if(BaseGet(responseString) != null)

        protected override System.Configuration.ConfigurationElement CreateNewElement()
            return new Company();

        protected override object GetElementKey(System.Configuration.ConfigurationElement element)
            return ((Company)element).Name;

and ConfigurationSection:

public class RegisterCompaniesConfig
        : ConfigurationSection

        public static RegisterCompaniesConfig GetConfig()
            return (RegisterCompaniesConfig)System.Configuration.ConfigurationManager.GetSection("RegisterCompanies") ?? new RegisterCompaniesConfig();

            [ConfigurationCollection(typeof(Companies), AddItemName = "Company")]
        public Companies Companies
                object o = this["Companies"];
                return o as Companies ;


and you must also register your new configuration section in web.config (app.config):

          <section name="Companies" type="blablabla.RegisterCompaniesConfig" ..>

then you load your config with

var config = RegisterCompaniesConfig.GetConfig();
foreach(var item in config.Companies)
   do something ..

Initializing a struct to 0

The first is easiest(involves less typing), and it is guaranteed to work, all members will be set to 0[Ref 1].
The second is more readable.

The choice depends on user preference or the one which your coding standard mandates.

[Ref 1] Reference C99 Standard

If there are fewer initializers in a brace-enclosed list than there are elements or members of an aggregate, or fewer characters in a string literal used to initialize an array of known size than there are elements in the array, the remainder of the aggregate shall be initialized implicitly the same as objects that have static storage duration.

Good Read:
C and C++ : Partial initialization of automatic structure

ubuntu "No space left on device" but there is tons of space

It's possible that you've run out of memory or some space elsewhere and it prompted the system to mount an overflow filesystem, and for whatever reason, it's not going away.

Try unmounting the overflow partition:

umount /tmp


umount overflow

Is it .yaml or .yml?

.yaml is apparently the official extension, because some applications fail when using .yml. On the other hand I am not familiar with any applications which use YAML code, but fail with a .yaml extension.

I just stumbled across this, as I was used to writing .yml in Ansible and Docker Compose. Out of habit I used .yml when writing Netplan files which failed silently. I finally figured out my mistake. The author of a popular Ansible Galaxy role for Netplan makes the same assumption in his code:

- name: Capturing Existing Configurations
    paths: /etc/netplan
    patterns: "*.yml,*.yaml"
  register: _netplan_configs

Yet any files with a .yml extension get ignored by Netplan in the same way as files with a .bak extension. As Netplan is very quiet, and gives no feedback whatsoever on success, even with netplan apply --debug, a config such as 01-netcfg.yml will fail silently without any meaningful feedback.

How can I change the app display name build with Flutter?

The way of changing the name for iOS and Android is clearly mentioned in the documentation as follows:

But, the case of iOS after you change the Display Name from Xcode, you are not able to run the application in the Flutter way, like flutter run.

Because the Flutter run expects the app name as Runner. Even if you change the name in Xcode, it doesn't work.

So, I fixed this as follows:

Move to the location on your Flutter project, ios/Runner.xcodeproj/project.pbxproj, and find and replace all instances of your new name with Runner.

Then everything should work in the flutter run way.

But don't forget to change the name display name on your next release time. Otherwise, the App Store rejects your name.

How to replace text in a column of a Pandas dataframe?

Use the vectorised str method replace:

In [30]:

df['range'] = df['range'].str.replace(',','-')
0    (2-30)
1  (50-290)


So if we look at what you tried and why it didn't work:


from the docs we see this desc:

str or regex: str: string exactly matching to_replace will be replaced with value

So because the str values do not match, no replacement occurs, compare with the following:

In [43]:

df = pd.DataFrame({'range':['(2,30)',',']})
df['range'].replace(',','-', inplace=True)
0    (2,30)
1         -
Name: range, dtype: object

here we get an exact match on the second row and the replacement occurs.

SPAN vs DIV (inline-block)

I think it will help you to understand the basic differences between Inline-Elements (e.g. span) and Block-Elements (e.g. div), in order to understand why "display: inline-block" is so useful.

Problem: inline elements (e.g. span, a, button, input etc.) take "margin" only horizontally (margin-left and margin-right) on, not vertically. Vertical spacing works only on block elements (or if "display:block" is set)

Solution: Only through "display: inline-block" will also take the vertical distance (top and bottom). Reason: Inline element Span, behaves now like a block element to the outside, but like an inline element inside

Here Code Examples:

 /* Inlineelement */

        span {
            margin: 30px;

        span {
            outline: firebrick dotted medium;
            background-color: antiquewhite;

        span.mitDisplayBlock {
            background: #a2a2a2;
            display: block;
            width: 200px;
            height: 200px;

        span.beispielMargin {
            margin: 20px;

        span.beispielMarginDisplayInlineBlock {
            display: inline-block;

        span.beispielMarginDisplayInline {
            display: inline;

        span.beispielMarginDisplayBlock {
            display: block;

        /* Blockelement */

        div {
            outline: orange dotted medium;
            background-color: deepskyblue;

        .paddingDiv {
            padding: 20px;
            background-color: blanchedalmond;

        .marginDivWrapper {
            background-color: aliceblue;


        .marginDiv {
            margin: 20px;
            background-color: blanchedalmond;
        /* Nur für das w3school Bild */

        #w3_DIV_1 {
            bottom: 0px;
            box-sizing: border-box;
            height: 391px;
            left: 0px;
            position: relative;
            right: 0px;
            text-size-adjust: 100%;
            top: 0px;
            width: 913.984px;
            perspective-origin: 456.984px 195.5px;
            transform-origin: 456.984px 195.5px;
            background: rgb(241, 241, 241) none repeat scroll 0% 0% / auto padding-box border-box;
            border: 2px dashed rgb(187, 187, 187);
            font: normal normal 400 normal 15px / 22.5px Lato, sans-serif;
            padding: 45px;
            transition: all 0.25s ease-in-out 0s;


        #w3_DIV_1:before {
            bottom: 349.047px;
            box-sizing: border-box;
            content: '"Margin"';
            display: block;
            height: 31px;
            left: 0px;
            position: absolute;
            right: 0px;
            text-align: center;
            text-size-adjust: 100%;
            top: 6.95312px;
            width: 909.984px;
            perspective-origin: 454.984px 15.5px;
            transform-origin: 454.984px 15.5px;
            font: normal normal 400 normal 21px / 31.5px Lato, sans-serif;


        #w3_DIV_2 {
            bottom: 0px;
            box-sizing: border-box;
            color: black;
            height: 297px;
            left: 0px;
            position: relative;
            right: 0px;
            text-decoration: none solid rgb(255, 255, 255);
            text-size-adjust: 100%;
            top: 0px;
            width: 819.984px;
            column-rule-color: rgb(255, 255, 255);
            perspective-origin: 409.984px 148.5px;
            transform-origin: 409.984px 148.5px;
            caret-color: rgb(255, 255, 255);
            background: rgb(76, 175, 80) none repeat scroll 0% 0% / auto padding-box border-box;
            border: 0px none rgb(255, 255, 255);
            font: normal normal 400 normal 15px / 22.5px Lato, sans-serif;
            outline: rgb(255, 255, 255) none 0px;
            padding: 45px;


        #w3_DIV_2:before {
            bottom: 258.578px;
            box-sizing: border-box;
            content: '"Border"';
            display: block;
            height: 31px;
            left: 0px;
            position: absolute;
            right: 0px;
            text-align: center;
            text-size-adjust: 100%;
            top: 7.42188px;
            width: 819.984px;
            perspective-origin: 409.984px 15.5px;
            transform-origin: 409.984px 15.5px;
            font: normal normal 400 normal 21px / 31.5px Lato, sans-serif;


        #w3_DIV_3 {
            bottom: 0px;
            box-sizing: border-box;
            height: 207px;
            left: 0px;
            position: relative;
            right: 0px;
            text-size-adjust: 100%;
            top: 0px;
            width: 729.984px;
            perspective-origin: 364.984px 103.5px;
            transform-origin: 364.984px 103.5px;
            background: rgb(241, 241, 241) none repeat scroll 0% 0% / auto padding-box border-box;
            font: normal normal 400 normal 15px / 22.5px Lato, sans-serif;
            padding: 45px;


        #w3_DIV_3:before {
            bottom: 168.344px;
            box-sizing: border-box;
            content: '"Padding"';
            display: block;
            height: 31px;
            left: 3.64062px;
            position: absolute;
            right: -3.64062px;
            text-align: center;
            text-size-adjust: 100%;
            top: 7.65625px;
            width: 729.984px;
            perspective-origin: 364.984px 15.5px;
            transform-origin: 364.984px 15.5px;
            font: normal normal 400 normal 21px / 31.5px Lato, sans-serif;


        #w3_DIV_4 {
            bottom: 0px;
            box-sizing: border-box;
            height: 117px;
            left: 0px;
            position: relative;
            right: 0px;
            text-size-adjust: 100%;
            top: 0px;
            width: 639.984px;
            perspective-origin: 319.984px 58.5px;
            transform-origin: 319.984px 58.5px;
            background: rgb(191, 201, 101) none repeat scroll 0% 0% / auto padding-box border-box;
            border: 2px dashed rgb(187, 187, 187);
            font: normal normal 400 normal 15px / 22.5px Lato, sans-serif;
            padding: 20px;


        #w3_DIV_4:before {
            box-sizing: border-box;
            content: '"Content"';
            display: block;
            height: 73px;
            text-align: center;
            text-size-adjust: 100%;
            width: 595.984px;
            perspective-origin: 297.984px 36.5px;
            transform-origin: 297.984px 36.5px;
            font: normal normal 400 normal 21px / 73.5px Lato, sans-serif;

   <h1> The Box model - content, padding, border, margin</h1>
    <h2> Inline element - span</h2>
    <span>Info: A span element can not have height and width (not without "display: block"), which means it takes the fixed inline size </span>

    <span class="beispielMargin">
        <b>Problem:</b> inline elements (eg span, a, button, input etc.) take "margin" only vertically (margin-left and margin-right)
        on, not horizontal. Vertical spacing works only on block elements (or if display: block is set) </span>

    <span class="beispielMarginDisplayInlineBlock">
        <b>Solution</b> Only through
        <b> "display: inline-block" </ b> will also take the vertical distance (top and bottom). Reason: Inline element Span,
        behaves now like a block element to the outside, but like an inline element inside</span>

    <span class="beispielMarginDisplayInline">Example: here "display: inline". See the margin with Inspector!</span>

    <span class="beispielMarginDisplayBlock">Example: here "display: block". See the margin with Inspector!</span>

    <span class="beispielMarginDisplayInlineBlock">Example: here "display: inline-block". See the margin with Inspector! </span>

    <span class="mitDisplayBlock">Only with the "Display" -property and "block" -Value in addition, a width and height can be assigned. "span" is then like
        a "div" block element.  </span>

    <h2>Inline-Element - Div</h2>
    <div> A div automatically takes "display: block." </ div>
    <div class = "paddingDiv"> Padding is for padding </ div>

    <div class="marginDivWrapper">
Wrapper encapsulates the example "marginDiv" to clarify the "margin" (distance from inner element "marginDiv" to the text)
        of the outer element "marginDivWrapper". Here 20px;)
    <div class = "marginDiv"> margin is for the margins </ div>
        And there, too, 20px;

    <h2>w3school sample image </h2>
    <a href="">CSS Box Model</a>
    <div id="w3_DIV_1">
        <div id="w3_DIV_2">
            <div id="w3_DIV_3">
                <div id="w3_DIV_4">

PHP Excel Header

The problem is you typed the wrong file extension for excel file. you used .xsl instead of xls.

I know i came in late but it can help future readers of this post.

Eclipse Bug: Unhandled event loop exception No more handles

Wow, what a variety of causes of these error messages! I'll throw one more out:

In my case, Eclipse 4.17 on Ubuntu 16.04LTS was showing these messages for multiple operations. It turns out that 16.04LTS has GTK 3.18, but Eclipse 4.17 requires GTK 3.20. Updating GTK ( made the error messages go away.

Is it possible to compile a program written in Python?

You dont have to compile it. the first you use it (import) it is compiled by the CPython interpreter. But if you really want to compile there are several options.

To compile to exe

Or 2 compile just a specific *.py file, you can just use

import py_compile

passing form data to another HTML page

Using pure JavaScript.It's very easy using local storage.
The first page form:

function getData()
    //gettting the values
    var email = document.getElementById("email").value;
    var password= document.getElementById("password").value; 
    var telephone= document.getElementById("telephone").value; 
    var mobile= document.getElementById("mobile").value; 
    //saving the values in local storage
    localStorage.setItem("txtValue", email);
    localStorage.setItem("txtValue1", password);
    localStorage.setItem("txtValue2", mobile);
    localStorage.setItem("txtValue3", telephone);   
    font-size: 25px;
    color: rgb(16, 8, 46);
    font-weight: bolder;

   <fieldset style="width: fit-content; margin: 0 auto; font-size: 30px;">
        <form action="action.html">
        <legend>Sign Up Form</legend>
        <label>Email:<br />
        <input type="text" name="email" id="email"/></label><br />
        <label>Password<br />
        <input type="text" name="password" id="password"/></label><br>
        <label>Mobile:<br />
        <input type="text" name="mobile" id="mobile"/></label><br />
        <label>Telephone:<br />
        <input type="text" name="telephone" id="telephone"/></label><br> 
        <input type="submit" value="Submit" onclick="getData()">

This is the second page:

//displaying the value from local storage to another page by their respective Ids
 <div style=" font-size: 30px;  color: rgb(32, 7, 63); text-align: center;">
    <div style="font-size: 40px; color: red; margin: 0 auto;">
        Here's Your data
    The Email is equal to: <span id="data"> Email</span><br> 
    The Password is equal to <span id="data1"> Password</span><br>
    The Mobile is equal to <span id="data2"> Mobile</span><br>
    The Telephone is equal to <span id="data3"> Telephone</span><br>

Important Note:

Please don't forget to give name "action.html" to the second html file to work the code properly. I can't use multiple pages in a snippet, that's why its not working here try in the browser in your editor where it will surely work.

How to make a machine trust a self-signed Java application

I was having the same issue. So I went to the Java options through Control Panel. Copied the web address that I was having an issue with to the exceptions and it was fixed.

Does JavaScript have the interface type (such as Java's 'interface')?

I know this is an old one, but I've recently found myself needing more and more to have a handy API for checking objects against interfaces. So I wrote this:

It's also available via NPM: npm install methodical

It basically does everything suggested above, with some options for being a bit more strict, and all without having to do loads of if (typeof x.method === 'function') boilerplate.

Hopefully someone finds it useful.

What does mysql error 1025 (HY000): Error on rename of './foo' (errorno: 150) mean?

It is indeed a foreign key error, you can find out using perror:

shell$ perror 150
MySQL error code 150: Foreign key constraint is incorrectly formed

To find out more details about what failed, you can use SHOW ENGINE INNODB STATUS and look for the LATEST FOREIGN KEY ERROR section it contains details about what is wrong.

In your case, it is most likely cause something is referencing the country_id column.

Setting ANDROID_HOME enviromental variable on Mac OS X

Could anybody post a working solution for doing this in the terminal?

ANDROID_HOME is usually a directory like .android. Its where things like the Debug Key will be stored.

export ANDROID_HOME=~/.android 

You can automate it for your login. Just add it to your .bash_profile (below is from my OS X 10.8.5 machine):

$ cat ~/.bash_profile
# MacPorts Installer addition on 2012-07-19 at 20:21:05
export PATH=/opt/local/bin:/opt/local/sbin:$PATH

# Android
export ANDROID_NDK_ROOT=/opt/android-ndk-r9
export ANDROID_SDK_ROOT=/opt/android-sdk
export JAVA_HOME=`/usr/libexec/java_home`
export ANDROID_HOME=~/.android

export PATH="$ANDROID_SDK_ROOT/tools/":"$ANDROID_SDK_ROOT/platform-tools/":"$PATH"

According to David Turner on the NDK Mailing List, both ANDROID_NDK_ROOT and ANDROID_SDK_ROOT need to be set because other tools depend on those values (see Recommended NDK Directory?).

After modifying ~/.bash_profile, then perform the following (or logoff and back on):

source ~/.bash_profile

adding classpath in linux

I don't like setting CLASSPATH. CLASSPATH is a global variable and as such it is evil:

  • If you modify it in one script, suddenly some java programs will stop working.
  • If you put there the libraries for all the things which you run, and it gets cluttered.
  • You get conflicts if two different applications use different versions of the same library.
  • There is no performance gain as libraries in the CLASSPATH are not shared - just their name is shared.
  • If you put the dot (.) or any other relative path in the CLASSPATH that means a different thing in each place - that will cause confusion, for sure.

Therefore the preferred way is to set the classpath per each run of the jvm, for example:

java -Xmx500m -cp ".:../somejar.jar:../mysql-connector-java-5.1.6-bin.jar"    "folder.subfolder../dit1/some.xml

If it gets long the standard procedure is to wrap it in a bash or batch script to save typing.

Merging two arrayLists into a new arrayList, with no duplicates and in order, in Java

I got your point that you don't wanna use the built-in functions for merging or remove duplicates from the ArrayList. Your first code is running forever because the outer for loop condition is 'Always True'. Since you are adding elements to plusArray, so the size of the plusArray is increasing with every addition and hence 'i' is always less than it. As a result the condition never fails and the program runs forever. Tip: Try to first merge the list and then from the merged list remove the duplicate elements. :)

Setting POST variable without using form

You can do it using jQuery. Example:

<script src=""></script>

        url : "next.php",
        type: "POST",
        data : "name=Denniss",
        success: function(data)
            //data - response from server

Can't create handler inside thread which has not called Looper.prepare()

The error is self-explanatory... doInBackground() runs on a background thread which, since it is not intended to loop, is not connected to a Looper.

You most likely don't want to directly instantiate a Handler at all... whatever data your doInBackground() implementation returns will be passed to onPostExecute() which runs on the UI thread.

   mActivity = ThisActivity.this; 

    mActivity.runOnUiThread(new Runnable() {
     public void run() {
     new asyncCreateText().execute();


Looks like you're trying to start an AsyncTask from a GL rendering thread... don't do that cos they won't ever Looper.loop() either. AsyncTasks are really designed to be run from the UI thread only.

The least disruptive fix would probably be to call Activity.runOnUiThread() with a Runnable that kicks off your AsyncTask.

Getting Image from API in Angular 4/5+?

You should set responseType: ResponseContentType.Blob in your GET-Request settings, because so you can get your image as blob and convert it later da base64-encoded source. You code above is not good. If you would like to do this correctly, then create separate service to get images from API. Beacuse it ism't good to call HTTP-Request in components.

Here is an working example:

Create image.service.ts and put following code:

Angular 4:

getImage(imageUrl: string): Observable<File> {
    return this.http
        .get(imageUrl, { responseType: ResponseContentType.Blob })
        .map((res: Response) => res.blob());

Angular 5+:

getImage(imageUrl: string): Observable<Blob> {
  return this.httpClient.get(imageUrl, { responseType: 'blob' });

Important: Since Angular 5+ you should use the new HttpClient.

The new HttpClient returns JSON by default. If you need other response type, so you can specify that by setting responseType: 'blob'. Read more about that here.

Now you need to create some function in your image.component.ts to get image and show it in html.

For creating an image from Blob you need to use JavaScript's FileReader. Here is function which creates new FileReader and listen to FileReader's load-Event. As result this function returns base64-encoded image, which you can use in img src-attribute:

imageToShow: any;

createImageFromBlob(image: Blob) {
   let reader = new FileReader();
   reader.addEventListener("load", () => {
      this.imageToShow = reader.result;
   }, false);

   if (image) {

Now you should use your created ImageService to get image from api. You should to subscribe to data and give this data to createImageFromBlob-function. Here is an example function:

getImageFromService() {
      this.isImageLoading = true;
      this.imageService.getImage(yourImageUrl).subscribe(data => {
        this.isImageLoading = false;
      }, error => {
        this.isImageLoading = false;

Now you can use your imageToShow-variable in HTML template like this:

<img [src]="imageToShow"
     alt="Place image title"
     *ngIf="!isImageLoading; else noImageFound">
<ng-template #noImageFound>
     <img src="fallbackImage.png" alt="Fallbackimage">

I hope this description is clear to understand and you can use it in your project.

See the working example for Angular 5+ here.

When to use cla(), clf() or close() for clearing a plot in matplotlib?

They all do different things, since matplotlib uses a hierarchical order in which a figure window contains a figure which may consist of many axes. Additionally, there are functions from the pyplot interface and there are methods on the Figure class. I will discuss both cases below.

pyplot interface

pyplot is a module that collects a couple of functions that allow matplotlib to be used in a functional manner. I here assume that pyplot has been imported as import matplotlib.pyplot as plt. In this case, there are three different commands that remove stuff:

plt.cla() clears an axes, i.e. the currently active axes in the current figure. It leaves the other axes untouched.

plt.clf() clears the entire current figure with all its axes, but leaves the window opened, such that it may be reused for other plots.

plt.close() closes a window, which will be the current window, if not specified otherwise.

Which functions suits you best depends thus on your use-case.

The close() function furthermore allows one to specify which window should be closed. The argument can either be a number or name given to a window when it was created using figure(number_or_name) or it can be a figure instance fig obtained, i.e., usingfig = figure(). If no argument is given to close(), the currently active window will be closed. Furthermore, there is the syntax close('all'), which closes all figures.

methods of the Figure class

Additionally, the Figure class provides methods for clearing figures. I'll assume in the following that fig is an instance of a Figure:

fig.clf() clears the entire figure. This call is equivalent to plt.clf() only if fig is the current figure.

fig.clear() is a synonym for fig.clf()

Note that even del fig will not close the associated figure window. As far as I know the only way to close a figure window is using plt.close(fig) as described above.

How to write some data to excel file(.xlsx)

Try this code

Microsoft.Office.Interop.Excel.Application oXL;
Microsoft.Office.Interop.Excel._Workbook oWB;
Microsoft.Office.Interop.Excel._Worksheet oSheet;
Microsoft.Office.Interop.Excel.Range oRng;
object misvalue = System.Reflection.Missing.Value;
    //Start Excel and get Application object.
    oXL = new Microsoft.Office.Interop.Excel.Application();
    oXL.Visible = true;

    //Get a new workbook.
    oWB = (Microsoft.Office.Interop.Excel._Workbook)(oXL.Workbooks.Add(""));
    oSheet = (Microsoft.Office.Interop.Excel._Worksheet)oWB.ActiveSheet;

    //Add table headers going cell by cell.
    oSheet.Cells[1, 1] = "First Name";
    oSheet.Cells[1, 2] = "Last Name";
    oSheet.Cells[1, 3] = "Full Name";
    oSheet.Cells[1, 4] = "Salary";

    //Format A1:D1 as bold, vertical alignment = center.
    oSheet.get_Range("A1", "D1").Font.Bold = true;
    oSheet.get_Range("A1", "D1").VerticalAlignment =

    // Create an array to multiple values at once.
    string[,] saNames = new string[5, 2];

    saNames[0, 0] = "John";
    saNames[0, 1] = "Smith";
    saNames[1, 0] = "Tom";

    saNames[4, 1] = "Johnson";

    //Fill A2:B6 with an array of values (First and Last Names).
    oSheet.get_Range("A2", "B6").Value2 = saNames;

    //Fill C2:C6 with a relative formula (=A2 & " " & B2).
    oRng = oSheet.get_Range("C2", "C6");
    oRng.Formula = "=A2 & \" \" & B2";

    //Fill D2:D6 with a formula(=RAND()*100000) and apply format.
    oRng = oSheet.get_Range("D2", "D6");
    oRng.Formula = "=RAND()*100000";
    oRng.NumberFormat = "$0.00";

    //AutoFit columns A:D.
    oRng = oSheet.get_Range("A1", "D1");

    oXL.Visible = false;
    oXL.UserControl = false;
    oWB.SaveAs("c:\\test\\test505.xls", Microsoft.Office.Interop.Excel.XlFileFormat.xlWorkbookDefault, Type.Missing, Type.Missing,
        false, false, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange,
        Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);



Code line wrapping - how to handle long lines

In general, I break lines before operators, and indent the subsequent lines:

Map<long parameterization> longMap
    = new HashMap<ditto>();

String longString = "some long text"
                  + " some more long text";

To me, the leading operator clearly conveys that "this line was continued from something else, it doesn't stand on its own." Other people, of course, have different preferences.

Spring JPA and persistence.xml

I have a test application set up using JPA/Hibernate & Spring, and my configuration mirrors yours with the exception that I create a datasource and inject it into the EntityManagerFactory, and moved the datasource specific properties out of the persistenceUnit and into the datasource. With these two small changes, my EM gets injected properly.

'LIKE ('%this%' OR '%that%') and something=else' not working

I know it's a bit old question but still people try to find efficient solution so instead you should use FULLTEXT index (it's available from MySQL 5.6.4).

Query on table with +35mil records by triple like in where block took ~2.5s but after adding index on these fields and using BOOLEAN MODE inside match ... against ... it took only 0.05s.

how to use jQuery ajax calls with node.js

Thanks to yojimbo for his answer. To add to his sample, I wanted to use the jquery method $.getJSON which puts a random callback in the query string so I also wanted to parse that out in the Node.js. I also wanted to pass an object back and use the stringify function.

This is my Client Side code.

function(jqXHR, textStatus, errorThrown) {
    alert('error ' + textStatus + " " + errorThrown);

This is my Server side Node.js

var http = require('http');
var querystring = require('querystring');
var url = require('url');

http.createServer(function (req, res) {
    //grab the callback from the query string   
    var pquery = querystring.parse(url.parse(req.url).query);   
    var callback = (pquery.callback ? pquery.callback : '');

    //we probably want to send an object back in response to the request
    var returnObject = {message: "Hello World!"};
    var returnObjectString = JSON.stringify(returnObject);

    //push back the response including the callback shenanigans
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end(callback + '(\'' + returnObjectString + '\')');

How to convert OutputStream to InputStream?

ByteArrayOutputStream buffer = (ByteArrayOutputStream) aOutputStream;
byte[] bytes = buffer.toByteArray();
InputStream inputStream = new ByteArrayInputStream(bytes);

Replace string within file contents

Using pathlib (

from pathlib import Path
file = Path('Stud.txt')
file.write_text(file.read_text().replace('A', 'Orange'))

If input and output files were different you would use two different variables for read_text and write_text.

If you wanted a change more complex than a single replacement, you would assign the result of read_text to a variable, process it and save the new content to another variable, and then save the new content with write_text.

If your file was large you would prefer an approach that does not read the whole file in memory, but rather process it line by line as show by Gareth Davidson in another answer (, which of course requires to use two distinct files for input and output.

Java Runtime.getRuntime(): getting output from executing a command line program

A quicker way is this:

public static String execCmd(String cmd) throws {
    java.util.Scanner s = new java.util.Scanner(Runtime.getRuntime().exec(cmd).getInputStream()).useDelimiter("\\A");
    return s.hasNext() ? : "";

Which is basically a condensed version of this:

public static String execCmd(String cmd) throws {
    Process proc = Runtime.getRuntime().exec(cmd); is = proc.getInputStream();
    java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A");
    String val = "";
    if (s.hasNext()) {
        val =;
    else {
        val = "";
    return val;

I know this question is old but I am posting this answer because I think this may be quicker.

Edit (For Java 7 and above)

Need to close Streams and Scanners. Using AutoCloseable for neat code:

public static String execCmd(String cmd) {
    String result = null;
    try (InputStream inputStream = Runtime.getRuntime().exec(cmd).getInputStream();
            Scanner s = new Scanner(inputStream).useDelimiter("\\A")) {
        result = s.hasNext() ? : null;
    } catch (IOException e) {
    return result;
} invalid stream header: 7371007E

If you are sending multiple objects, it's often simplest to put them some kind of holder/collection like an Object[] or List. It saves you having to explicitly check for end of stream and takes care of transmitting explicitly how many objects are in the stream.

EDIT: Now that I formatted the code, I see you already have the messages in an array. Simply write the array to the object stream, and read the array on the server side.

Your "server read method" is only reading one object. If it is called multiple times, you will get an error since it is trying to open several object streams from the same input stream. This will not work, since all objects were written to the same object stream on the client side, so you have to mirror this arrangement on the server side. That is, use one object input stream and read multiple objects from that.

(The error you get is because the objectOutputStream writes a header, which is expected by objectIutputStream. As you are not writing multiple streams, but simply multiple objects, then the next objectInputStream created on the socket input fails to find a second header, and throws an exception.)

To fix it, create the objectInputStream when you accept the socket connection. Pass this objectInputStream to your server read method and read Object from that.

Right Align button in horizontal LinearLayout

try this one

 <?xml version="1.0" encoding="utf-8"?>
    android:orientation="horizontal"  >

  <RelativeLayout xmlns:android=""
   android:orientation="horizontal" >

    android:textSize="20sp" />

    android:text="add" />


How to make sure that string is valid JSON using JSON.NET

This method doesn't require external libraries

using System.Web.Script.Serialization;
bool IsValidJson(string json)
        try {
            var serializer = new JavaScriptSerializer();
            dynamic result = serializer.DeserializeObject(json);
            return true;
        } catch { return false; }

How can I find an element by CSS class with XPath?

The ONLY right way to do it with XPath :

//div[contains(concat(" ", normalize-space(@class), " "), " Test ")]

The function normalize-space strips leading and trailing whitespace, and also replaces sequences of whitespace characters by a single space.


If not need many of these Xpath queries, you might want to use a library that converts CSS selectors to XPath, as CSS selectors are usually a lot easier to both read and write than XPath queries. For example, in this case, you could use both div[class~="Test"] and div.Test to get the same result.

Some libraries I've been able to find :

What is the best way to create a string array in python?

If you want to take input from user here is the code

If each string is given in new line:

strs = [input() for i in range(size)]

If the strings are separated by spaces:

strs = list(input().split())

How to compare two dates in Objective-C

Cocoa has couple of methods for this:

in NSDate

– isEqualToDate:  
– earlierDate:  
– laterDate:  
– compare:

When you use - (NSComparisonResult)compare:(NSDate *)anotherDate ,you get back one of these:

The receiver and anotherDate are exactly equal to each other, NSOrderedSame
The receiver is later in time than anotherDate, NSOrderedDescending
The receiver is earlier in time than anotherDate, NSOrderedAscending.


NSDate * now = [NSDate date];
NSDate * mile = [[NSDate alloc] initWithString:@"2001-03-24 10:45:32 +0600"];
NSComparisonResult result = [now compare:mile];

NSLog(@"%@", now);
NSLog(@"%@", mile);

switch (result)
    case NSOrderedAscending: NSLog(@"%@ is in future from %@", mile, now); break;
    case NSOrderedDescending: NSLog(@"%@ is in past from %@", mile, now); break;
    case NSOrderedSame: NSLog(@"%@ is the same as %@", mile, now); break;
    default: NSLog(@"erorr dates %@, %@", mile, now); break;

[mile release];

Set a default parameter value for a JavaScript function

Yes, This will work in Javascript. You can also do that:

function func(a=10,b=20)
    alert (a+' and '+b);

func(); // Result: 10 and 20

func(12); // Result: 12 and 20

func(22,25); // Result: 22 and 25

Copy data from one column to other column (which is in a different table)

It can be solved by using different attribute.

  • Use the cell Control click event.
  • Select the column value that your transpose to anther column.
  • send the selected value to the another text box or level whatever you fill convenient and a complementary button to modify the selected property.
  • update the whole stack op the database and make a algorithm with sql query to overcome this one to transpose it into the another column.

Quick way to retrieve user information Active Directory

You can simplify this code to:

        DirectorySearcher searcher = new DirectorySearcher();
        searcher.Filter = "(&(objectCategory=user)(cn=steve.evans))";

        SearchResultCollection results = searcher.FindAll();

        if (results.Count == 1)
            //do what you want to do
        else if (results.Count == 0)
            //user does not exist
            //found more than one user
            //something is wrong

If you can narrow down where the user is you can set searcher.SearchRoot to a specific OU that you know the user is under.

You should also use objectCategory instead of objectClass since objectCategory is indexed by default.

You should also consider searching on an attribute other than CN. For example it might make more sense to search on the username (sAMAccountName) since it's guaranteed to be unique.

Why is there an unexplainable gap between these inline-block div elements?

In this instance, your div elements have been changed from block level elements to inline elements. A typical characteristic of inline elements is that they respect the whitespace in the markup. This explains why a gap of space is generated between the elements. (example)

There are a few solutions that can be used to solve this.

Method 1 - Remove the whitespace from the markup

Example 1 - Comment the whitespace out: (example)


Example 2 - Remove the line breaks: (example)


Example 3 - Close part of the tag on the next line (example)


Example 4 - Close the entire tag on the next line: (example)


Method 2 - Reset the font-size

Since the whitespace between the inline elements is determined by the font-size, you could simply reset the font-size to 0, and thus remove the space between the elements.

Just set font-size: 0 on the parent elements, and then declare a new font-size for the children elements. This works, as demonstrated here (example)

#parent {
    font-size: 0;

#child {
    font-size: 16px;

This method works pretty well, as it doesn't require a change in the markup; however, it doesn't work if the child element's font-size is declared using em units. I would therefore recommend removing the whitespace from the markup, or alternatively floating the elements and thus avoiding the space generated by inline elements.

Method 3 - Set the parent element to display: flex

In some cases, you can also set the display of the parent element to flex. (example)

This effectively removes the spaces between the elements in supported browsers. Don't forget to add appropriate vendor prefixes for additional support.

.parent {
    display: flex;
.parent > div {
    display: inline-block;
    padding: 1em;
    border: 2px solid #f00;

.parent {_x000D_
    display: flex;_x000D_
.parent > div {_x000D_
    display: inline-block;_x000D_
    padding: 1em;_x000D_
    border: 2px solid #f00;_x000D_
<div class="parent">_x000D_

Sides notes:

It is incredibly unreliable to use negative margins to remove the space between inline elements. Please don't use negative margins if there are other, more optimal, solutions.

Getting request URL in a servlet

The getRequestURL() omits the port when it is 80 while the scheme is http, or when it is 443 while the scheme is https.

So, just use getRequestURL() if all you want is obtaining the entire URL. This does however not include the GET query string. You may want to construct it as follows then:

StringBuffer requestURL = request.getRequestURL();
if (request.getQueryString() != null) {
String completeURL = requestURL.toString();

Chmod 777 to a folder and all contents

You can also use chmod 777 *

This will give permissions to all files currently in the folder and files added in the future without giving permissions to the directory itself.

NOTE: This should be done in the folder where the files are located. For me it was an images that had an issue so I went to my images folder and did this.

how to change text box value with jQuery?

If .val() is not working, I would suggest you to use the .attr() attribute

  $(function() {
    $("your_button").on("click", function() {
      $("your_textbox").val("your value");

Download a div in a HTML page as pdf using javascript

Yes, it's possible to To capture div as PDFs in JS. You can can check the solution provided by They have nice and clean JavaScript API which will allow you to capture the content of a single HTML element such as a div or a span.

So, yo use it you will need and app+key and the free SDK. The usage of it is as following:

Let's say you have a HTML:

<div id="features">
    <h4>Acme Camera</h4>
    <label>Price</label>$399<br />
    <label>Rating</label>4.5 out of 5
<p>Cras ut velit sed purus porttitor aliquam. Nulla tristique magna ac libero tempor, ac vestibulum felisvulput ate. Nam ut velit eget
risus porttitor tristique at ac diam. Sed nisi risus, rutrum a metus suscipit, euismod tristique nulla. Etiam venenatis rutrum risus at
blandit. In hac habitasse platea dictumst. Suspendisse potenti. Phasellus eget vehicula felis.</p>

To capture what is under the features id you will need to:

//add the sdk
<script type="text/javascript" src="grabzit.min.js"></script>
<script type="text/javascript">
//login with your key and secret. 
GrabzIt("KEY", "SECRET").ConvertURL("",
{"target": "#features", "format": "pdf"}).Create();

You need to replace the with your target url and #feature per your CSS selector.

That's all. Now, when the page is loaded an image screenshot will now be created in the same location as the script tag, which will contain all of the contents of the features div and nothing else.

The are other configuration and customization you can do to the div-screenshot mechanism, please check them out here

Current date and time - Default in MVC razor

You could initialize ReturnDate on the model before sending it to the view.

In the controller:

public ActionResult SomeAction()
    var viewModel = new MyActionViewModel
        ReturnDate = System.DateTime.Now

    return View(viewModel);

Any free WPF themes?

Not purely themes, but MahApps.Metro provides Windows 8 Look and feel with a few variants like dark and light base themes with green,blue etc for text and others. Its pretty cool and can be used out of the box.

Reading settings from app.config or web.config in .NET

I have been trying to find a fix for this same issue for a couple of days now. I was able to resolve this by adding a key within the appsettings tag in the web.config file. This should override the .dll file when using the helper.

        <add key="loginUrl" value="~/RedirectValue.cshtml" />
        <add key="autoFormsAuthentication" value="false"/>

How do I fix twitter-bootstrap on IE?

I had this problem recently. I made these settings change. And it worked for me. !

verify these settings

Import an existing git project into GitLab?


Just simply run this command in an existing Git repository

cd existing_repo
git remote rename origin previous-hosts
git remote add gitlab [email protected]:hutber/
git push -u gitlab --all
git push -u gitlab --tags

Is there a Max function in SQL Server that takes two values like Math.Max in .NET?

The other answers are good, but if you have to worry about having NULL values, you may want this variant:

SELECT o.OrderId, 
   CASE WHEN ISNULL(o.NegotiatedPrice, o.SuggestedPrice) > ISNULL(o.SuggestedPrice, o.NegotiatedPrice)
        THEN ISNULL(o.NegotiatedPrice, o.SuggestedPrice)
        ELSE ISNULL(o.SuggestedPrice, o.NegotiatedPrice)
FROM Order o

Make an existing Git branch track a remote branch?

For Git versions 1.8.0 and higher:

Actually for the accepted answer to work:

git remote add upstream <remote-url>
git fetch upstream
git branch -f --track qa upstream/qa
# OR Git version 1.8.0 and higher:
git branch --set-upstream-to=upstream/qa
# Gitversions lower than 1.8.0
git branch --set-upstream qa upstream/qa

Storing and retrieving datatable from session

You can do it like that but storing a DataSet object in Session is not very efficient. If you have a web app with lots of users it will clog your server memory really fast.

If you really must do it like that I suggest removing it from the session as soon as you don't need the DataSet.

Pretty printing XML with javascript

Use above method for pretty print and then add this in any div by using jquery text() method. for example id of div is xmldiv then use :


error running apache after xampp install

I got the same error when xampp was installed on windows 10. server certificate does NOT include an ID which matches the server name

So I opened httpd-ssl.conf file in xampp folder and changed the following line



ServerName localhost

And the problem was fixed.

Delayed rendering of React components

Depends on your use case.

If you want to do some animation of children blending in, use the react animation add-on: Otherwise, make the rendering of the children dependent on props and add the props after some delay.

I wouldn't delay in the component, because it will probably haunt you during testing. And ideally, components should be pure.

Stack Memory vs Heap Memory

In C++ the stack memory is where local variables get stored/constructed. The stack is also used to hold parameters passed to functions.

The stack is very much like the std::stack class: you push parameters onto it and then call a function. The function then knows that the parameters it expects can be found on the end of the stack. Likewise, the function can push locals onto the stack and pop them off it before returning from the function. (caveat - compiler optimizations and calling conventions all mean things aren't this simple)

The stack is really best understood from a low level and I'd recommend Art of Assembly - Passing Parameters on the Stack. Rarely, if ever, would you consider any sort of manual stack manipulation from C++.

Generally speaking, the stack is preferred as it is usually in the CPU cache, so operations involving objects stored on it tend to be faster. However the stack is a limited resource, and shouldn't be used for anything large. Running out of stack memory is called a Stack buffer overflow. It's a serious thing to encounter, but you really shouldn't come across one unless you have a crazy recursive function or something similar.

Heap memory is much as rskar says. In general, C++ objects allocated with new, or blocks of memory allocated with the likes of malloc end up on the heap. Heap memory almost always must be manually freed, though you should really use a smart pointer class or similar to avoid needing to remember to do so. Running out of heap memory can (will?) result in a std::bad_alloc.

Python - How do you run a .py file?

Since you seem to be on windows you can do this so python <>. Check that python's bin folder is in your PATH, or you can do c:\python23\bin\python <>. Python is an interpretive language and so you need the interpretor to run your file, much like you need java runtime to run a jar file.

Fitting a density curve to a histogram in R

If I understand your question correctly, then you probably want a density estimate along with the histogram:

X <- c(rep(65, times=5), rep(25, times=5), rep(35, times=10), rep(45, times=4))
hist(X, prob=TRUE)            # prob=TRUE for probabilities not counts
lines(density(X))             # add a density estimate with defaults
lines(density(X, adjust=2), lty="dotted")   # add another "smoother" density

Edit a long while later:

Here is a slightly more dressed-up version:

X <- c(rep(65, times=5), rep(25, times=5), rep(35, times=10), rep(45, times=4))
hist(X, prob=TRUE, col="grey")# prob=TRUE for probabilities not counts
lines(density(X), col="blue", lwd=2) # add a density estimate with defaults
lines(density(X, adjust=2), lty="dotted", col="darkgreen", lwd=2) 

along with the graph it produces:

enter image description here

Online PHP syntax checker / validator

Here is also a good and simple site to check your php codes and share your code with fiends :

D3.js: How to get the computed width and height for an arbitrary element?

.getBoundingClientRect() returns the size of an element and its position relative to the viewport.We can easily get following

  • left, right
  • top, bottom
  • height, width

Example :

var element ='.elementClassName').node();

Automating the InvokeRequired code pattern

Lee's approach can be simplified further

public static void InvokeIfRequired(this Control control, MethodInvoker action)
    // See Update 2 for edits Mike de Klerk suggests to insert here.

    if (control.InvokeRequired) {
    } else {

And can be called like this

richEditControl1.InvokeIfRequired(() =>
    // Do anything you want with the control here
    richEditControl1.RtfText = value;

There is no need to pass the control as parameter to the delegate. C# automatically creates a closure.


According to several other posters Control can be generalized as ISynchronizeInvoke:

public static void InvokeIfRequired(this ISynchronizeInvoke obj,
                                         MethodInvoker action)
    if (obj.InvokeRequired) {
        var args = new object[0];
        obj.Invoke(action, args);
    } else {

DonBoitnott pointed out that unlike Control the ISynchronizeInvoke interface requires an object array for the Invoke method as parameter list for the action.


Edits suggested by Mike de Klerk (see comment in 1st code snippet for insert point):

// When the form, thus the control, isn't visible yet, InvokeRequired  returns false,
// resulting still in a cross-thread exception.
while (!control.Visible)

See ToolmakerSteve's comment below for concerns about this suggestion.

Pandas percentage of total with groupby

Simple way I have used is a merge after the 2 groupby's then doing simple division.

import numpy as np
import pandas as pd
df = pd.DataFrame({'state': ['CA', 'WA', 'CO', 'AZ'] * 3,
               'office_id': list(range(1, 7)) * 2,
               'sales': [np.random.randint(100000, 999999) for _ in range(12)]})

state_office = df.groupby(['state', 'office_id'])['sales'].sum().reset_index()
state = df.groupby(['state'])['sales'].sum().reset_index()
state_office = state_office.merge(state, left_on='state', right_on ='state', how = 'left')
state_office['sales_ratio'] = 100*(state_office['sales_x']/state_office['sales_y'])

   state  office_id  sales_x  sales_y  sales_ratio
0     AZ          2   222579  1310725    16.981365
1     AZ          4   252315  1310725    19.250033
2     AZ          6   835831  1310725    63.768601
3     CA          1   405711  2098663    19.331879
4     CA          3   710581  2098663    33.858747
5     CA          5   982371  2098663    46.809373
6     CO          1   404137  1096653    36.851857
7     CO          3   217952  1096653    19.874290
8     CO          5   474564  1096653    43.273852
9     WA          2   535829  1543854    34.707233
10    WA          4   548242  1543854    35.511259
11    WA          6   459783  1543854    29.781508

When to use React "componentDidUpdate" method?

This lifecycle method is invoked as soon as the updating happens. The most common use case for the componentDidUpdate() method is updating the DOM in response to prop or state changes.

You can call setState() in this lifecycle, but keep in mind that you will need to wrap it in a condition to check for state or prop changes from previous state. Incorrect usage of setState() can lead to an infinite loop. Take a look at the example below that shows a typical usage example of this lifecycle method.

componentDidUpdate(prevProps) {
 //Typical usage, don't forget to compare the props
 if (this.props.userName !== prevProps.userName) {

Notice in the above example that we are comparing the current props to the previous props. This is to check if there has been a change in props from what it currently is. In this case, there won’t be a need to make the API call if the props did not change.

For more info, refer to the official docs:

SASS :not selector

I tried re-creating this, and .someclass.notip was being generated for me but .someclass:not(.notip) was not, for as long as I did not have the @mixin tip() defined. Once I had that, it all worked.

$dropdown-width: 100px;
$comp-tip: true;

@mixin tip($pos:right) {


@mixin dropdown-pos($pos:right) {
  &:not(.notip) {
    @if $comp-tip == true{
      @if $pos == right {
        top:$dropdown-width * -0.6;
        background-color: #f00;
        @include tip($pos:$pos);
  &.notip {
    @if $pos == right {
      top: 0;
      left:$dropdown-width * 0.8;
      background-color: #00f;

.someclass { @include dropdown-pos(); }

EDIT: is a good place to debug your SASS because it gives you error messages. Undefined mixin 'tip'. it what I get when I remove @mixin tip($pos:right) { }

How to get to Model or Viewbag Variables in a Script Tag

When you're doing this

var model = @Html.Raw(Json.Encode(Model));

You're probably getting a JSON string, and not a JavaScript object.

You need to parse it in to an object:

var model = JSON.parse(model); //or $.parseJSON() since if jQuery is included

How to use XPath in Python?

Another library is 4Suite:

I do not know how spec-compliant it is. But it has worked very well for my use. It looks abandoned.

The type initializer for 'Oracle.DataAccess.Client.OracleConnection' threw an exception

Two options:

  • Install Oracle client on the PC you want to run your program on

  • Use Oracle.ManagedDataAccess.dll

You can get it on NuGet (search 'oracle managed') or download (link is to a beta version, but points you in the right direction)

I use this so that the computers I deploy onto don't need Oracle client installed.

N.B. in my opinion this is good for console apps but annoying if you intend to install your application, so I install the client in that case.

"insufficient memory for the Java Runtime Environment " message in eclipse

In your Eclipse installation directory you should be able to find the file eclipse.ini. Open it and find the -vmargs section. Adjust the value of:


In this example it is set to 1GB.

Java client certificates over HTTPS/SSL

For me, this is what worked using Apache HttpComponents ~ HttpClient 4.x:

    KeyStore keyStore  = KeyStore.getInstance("PKCS12");
    FileInputStream instream = new FileInputStream(new File("client-p12-keystore.p12"));
    try {
        keyStore.load(instream, "helloworld".toCharArray());
    } finally {

    // Trust own CA and all self-signed certs
    SSLContext sslcontext = SSLContexts.custom()
        .loadKeyMaterial(keyStore, "helloworld".toCharArray())
        //.loadTrustMaterial(trustStore, new TrustSelfSignedStrategy()) //custom trust store
    // Allow TLSv1 protocol only
    SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
        new String[] { "TLSv1" },
        SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER); //TODO
    CloseableHttpClient httpclient = HttpClients.custom()
        .setHostnameVerifier(SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER) //TODO
    try {

        HttpGet httpget = new HttpGet("https://localhost:8443/secure/index");

        System.out.println("executing request" + httpget.getRequestLine());

        CloseableHttpResponse response = httpclient.execute(httpget);
        try {
            HttpEntity entity = response.getEntity();

            if (entity != null) {
                System.out.println("Response content length: " + entity.getContentLength());
        } finally {
    } finally {

The P12 file contains the client certificate and client private key, created with BouncyCastle:

public static byte[] convertPEMToPKCS12(final String keyFile, final String cerFile,
    final String password)
    throws IOException, CertificateException, KeyStoreException, NoSuchAlgorithmException,
    // Get the private key
    FileReader reader = new FileReader(keyFile);

    PEMParser pem = new PEMParser(reader);
    PEMKeyPair pemKeyPair = ((PEMKeyPair)pem.readObject());
    JcaPEMKeyConverter jcaPEMKeyConverter = new JcaPEMKeyConverter().setProvider("BC");
    KeyPair keyPair = jcaPEMKeyConverter.getKeyPair(pemKeyPair);

    PrivateKey key = keyPair.getPrivate();


    // Get the certificate
    reader = new FileReader(cerFile);
    pem = new PEMParser(reader);

    X509CertificateHolder certHolder = (X509CertificateHolder) pem.readObject(); x509Certificate =
        new JcaX509CertificateConverter().setProvider("BC")


    // Put them into a PKCS12 keystore and write it to a byte[]
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    KeyStore ks = KeyStore.getInstance("PKCS12", "BC");
    ks.setKeyEntry("key-alias", (Key) key, password.toCharArray(),
        new[]{x509Certificate});, password.toCharArray());
    return bos.toByteArray();

How to use readline() method in Java?

In summary: I would be careful as to what code you copy. It is possible you are copying code which happens to work, rather than well chosen code.

In intnumber, parseInt is used and in floatnumber valueOf is used why so?

There is no good reason I can see. It's an inconsistent use of the APIs as you suspect.

Java is case sensitive, and there isn't any Readline() method. Perhaps you mean readLine().

DataInputStream.readLine() is deprecated in favour of using BufferedReader.readLine();

However, for your case, I would use the Scanner class.

Scanner sc = new Scanner(;
int intNum = sc.nextInt();
float floatNum = sc.nextFloat();

If you want to know what a class does I suggest you have a quick look at the Javadoc.

What is pipe() function in Angular

Don't get confused with the concepts of Angular and RxJS

We have pipes concept in Angular and pipe() function in RxJS.

1) Pipes in Angular: A pipe takes in data as input and transforms it to the desired output

2) pipe() function in RxJS: You can use pipes to link operators together. Pipes let you combine multiple functions into a single function.

The pipe() function takes as its arguments the functions you want to combine, and returns a new function that, when executed, runs the composed functions in sequence. (search for pipes in this URL, you can find the same)

So according to your question, you are referring pipe() function in RxJS

How to properly use unit-testing's assertRaises() with NoneType objects?

The problem is the TypeError gets raised 'before' assertRaises gets called since the arguments to assertRaises need to be evaluated before the method can be called. You need to pass a lambda expression like:

self.assertRaises(TypeError, lambda: self.testListNone[:1])

How can I convert a date into an integer?

Here what you can try:

var d = Date.parse("2016-07-19T20:23:01.804Z");
alert(d); //this is in milliseconds

How to change a particular element of a C++ STL vector

Even though @JamesMcNellis answer is a valid one I would like to explain something about error handling and also the fact that there is another way of doing what you want.

You have four ways of accessing a specific item in a vector:

  • Using the [] operator
  • Using the member function at(...)
  • Using an iterator in combination with a given offset
  • Using std::for_each from the algorithm header of the standard C++ library. This is another way which I can recommend (it uses internally an iterator). You can read more about it for example here.

In the following examples I will be using the following vector as a lab rat and explaining the first three methods:

static const int arr[] = {1, 2, 3, 4};
std::vector<int> v(arr, arr+sizeof(arr)/sizeof(arr[0]));

This creates a vector as seen below:

1 2 3 4

First let's look at the [] way of doing things. It works in pretty much the same way as you expect when working with a normal array. You give an index and possibly you access the item you want. I say possibly because the [] operator doesn't check whether the vector actually has that many items. This leads to a silent invalid memory access. Example:

v[10] = 9;

This may or may not lead to an instant crash. Worst case is of course is if it doesn't and you actually get what seems to be a valid value. Similar to arrays this may lead to wasted time in trying to find the reason why for example 1000 lines of code later you get a value of 100 instead of 234, which is somewhat connected to that very location where you retrieve an item from you vector.

A much better way is to use at(...). This will automatically check for out of bounds behaviour and break throwing an std::out_of_range. So in the case when we have = 9;

We will get:

terminate called after throwing an instance of 'std::out_of_range'
what(): vector::_M_range_check: __n (which is 10) >= this->size() (which is 4)

The third way is similar to the [] operator in the sense you can screw things up. A vector just like an array is a sequence of continuous memory blocks containing data of the same type. This means that you can use your starting address by assigning it to an iterator and then just add an offset to this iterator. The offset simply stands for how many items after the first item you want to traverse:

std::vector<int>::iterator it = v.begin(); // First element of your vector
*(it+0) = 9;  // offest = 0 basically means accessing v.begin()
// Now we have 9 2 3 4 instead of 1 2 3 4
*(it+1) = -1; // offset = 1 means first item of v plus an additional one
// Now we have 9 -1 3 4 instead of 9 2 3 4
// ...

As you can see we can also do

*(it+10) = 9;

which is again an invalid memory access. This is basically the same as using at(0 + offset) but without the out of bounds error checking.

I would advice using at(...) whenever possible not only because it's more readable compared to the iterator access but because of the error checking for invalid index that I have mentioned above for both the iterator with offset combination and the [] operator.

setValue:forUndefinedKey: this class is not key value coding-compliant for the key

This error is something else!

Here is how i Fixed it. I'm using xcode Version 6.1.1 and using swift. I got this error every time my app tried to perform a segue to jump to the next screen. Here what I did.

  1. Checked that the button was connected to the right action.(This wasn't the problem, but still good to check)
  2. Check that the button does not have any additional actions or outlets that you may have created by mistake. (This wasn't the problem, but still good to check)
  3. Check the logs and make sure that all the buttons in the NEXT SCREEN have the correct actions, and if there are any segues, make sure that they have a unique identifier. (This was the problem)
    • One of the segues did not have a unique identifier
    • One of the buttons had an action and two outlets that I created by mistake.

Delete any additional outlets and make sure that you the segues to the next screen have unique identifiers.


How to get the Google Map based on Latitude on Longitude?

Firstly add a div with id.

<div id="my_map_add" style="width:100%;height:300px;"></div>

<script type="text/javascript">
function my_map_add() {
var myMapCenter = new google.maps.LatLng(28.5383866, 77.34916609);
var myMapProp = {center:myMapCenter, zoom:12, scrollwheel:false, draggable:false, mapTypeId:google.maps.MapTypeId.ROADMAP};
var map = new google.maps.Map(document.getElementById("my_map_add"),myMapProp);
var marker = new google.maps.Marker({position:myMapCenter});

<script src=""></script>

Generate a unique id

We can do something like this

string TransactionID = "BTRF"+DateTime.Now.Ticks.ToString().Substring(0, 10);

Select All as default value for Multivalue parameter

Using dataset with default values is one way, but you must use query for Available values and for Default Values, if values are hard coded in Available values tab, then you must define default values as expressions. Pictures should explain everything

Create Parameter (if not automaticly created)

Create Parameter

Define values - wrong way example

Define values - wrong way

Define values - correct way example

Define values - correct way

Set default values - you must define all default values reflecting available values to make "Select All" by default, if you won't define all only those defined will be selected by default.

Set default values

The Result

The result

One picture for Data type: Int

One picture for Data type Int

Select count(*) from result query

select count(*) from(select count(SID) from Test where Date = '2012-12-10' group by SID)select count(*) from(select count(SID) from Test where Date = '2012-12-10' group by SID)

should works

how to parse json using groovy

Have you tried using JsonSlurper?

Example usage:

def slurper = new JsonSlurper()
def result = slurper.parseText('{"person":{"name":"Guillaume","age":33,"pets":["dog","cat"]}}')

assert == "Guillaume"
assert result.person.age == 33
assert result.person.pets.size() == 2
assert result.person.pets[0] == "dog"
assert result.person.pets[1] == "cat"

How to set time to a date object in java

Can you show code which you use for setting date object? Anyway< you can use this code for intialisation of date:

new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").parse("2011-01-01 00:00:00")

Remove duplicated rows using dplyr

Most of the time, the best solution is using distinct() from dplyr, as has already been suggested.

However, here's another approach that uses the slice() function from dplyr.

# Generate fake data for the example
  df <- data.frame(
    x = sample(0:1, 10, replace = T),
    y = sample(0:1, 10, replace = T),
    z = 1:10

# In each group of rows formed by combinations of x and y
# retain only the first row

    df %>%
      group_by(x, y) %>%

Difference from using the distinct() function

The advantage of this solution is that it makes it explicit which rows are retained from the original dataframe, and it can pair nicely with the arrange() function.

Let's say you had customer sales data and you wanted to retain one record per customer, and you want that record to be the one from their latest purchase. Then you could write:

customer_purchase_data %>%
   arrange(desc(Purchase_Date)) %>%
   group_by(Customer_ID) %>%

Change the Textbox height?

This is what worked nicely for me since all I wanted to do was set the height of the textbox. The property is Read-Only and the property is in the Unit class so you can't just set it. So I just created a new Unit and the constructor lets me set the height, then set the textbox to that unit instead.

Unit height = txtTextBox.Height;
double oldHeight = height.Value;
double newHeight = height.Value + 20; //Added 20 pixels
Unit newHeightUnit = new Unit(newHeight);
txtTextBox.Height = newHeightUnit;

How to split a python string on new line characters

? Splitting line in Python:

Have you tried using str.splitlines() method?:

From the docs:


Return a list of the lines in the string, breaking at line boundaries. Line breaks are not included in the resulting list unless keepends is given and true.

For example:

>>> 'Line 1\n\nLine 3\rLine 4\r\n'.splitlines()
['Line 1', '', 'Line 3', 'Line 4']

>>> 'Line 1\n\nLine 3\rLine 4\r\n'.splitlines(True)
['Line 1\n', '\n', 'Line 3\r', 'Line 4\r\n']

Which delimiters are considered?

This method uses the universal newlines approach to splitting lines.

The main difference between Python 2.X and Python 3.X is that the former uses the universal newlines approach to splitting lines, so "\r", "\n", and "\r\n" are considered line boundaries for 8-bit strings, while the latter uses a superset of it that also includes:

  • \v or \x0b: Line Tabulation (added in Python 3.2).
  • \f or \x0c: Form Feed (added in Python 3.2).
  • \x1c: File Separator.
  • \x1d: Group Separator.
  • \x1e: Record Separator.
  • \x85: Next Line (C1 Control Code).
  • \u2028: Line Separator.
  • \u2029: Paragraph Separator.

splitlines VS split:

Unlike str.split() when a delimiter string sep is given, this method returns an empty list for the empty string, and a terminal line break does not result in an extra line:

>>> ''.splitlines()

>>> 'Line 1\n'.splitlines()
['Line 1']

While str.split('\n') returns:

>>> ''.split('\n')

>>> 'Line 1\n'.split('\n')
['Line 1', '']

?? Removing additional whitespace:

If you also need to remove additional leading or trailing whitespace, like spaces, that are ignored by str.splitlines(), you could use str.splitlines() together with str.strip():

>>> [str.strip() for str in 'Line 1  \n  \nLine 3 \rLine 4 \r\n'.splitlines()]
['Line 1', '', 'Line 3', 'Line 4']

? Removing empty strings (''):

Lastly, if you want to filter out the empty strings from the resulting list, you could use filter():

>>> # Python 2.X:
>>> filter(bool, 'Line 1\n\nLine 3\rLine 4\r\n'.splitlines())
['Line 1', 'Line 3', 'Line 4']

>>> # Python 3.X:
>>> list(filter(bool, 'Line 1\n\nLine 3\rLine 4\r\n'.splitlines()))
['Line 1', 'Line 3', 'Line 4']

Additional comment regarding the original question:

As the error you posted indicates and Burhan suggested, the problem is from the print. There's a related question about that could be useful to you: UnicodeEncodeError: 'charmap' codec can't encode - character maps to <undefined>, print function

IPhone/IPad: How to get screen width programmatically?

Take a look at UIScreen.


CGFloat width = [UIScreen mainScreen].bounds.size.width;

Take a look at the applicationFrame property if you don't want the status bar included (won't affect the width).

UPDATE: It turns out UIScreen (-bounds or -applicationFrame) doesn't take into account the current interface orientation. A more correct approach would be to ask your UIView for its bounds -- assuming this UIView has been auto-rotated by it's View controller.

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
    CGFloat width = CGRectGetWidth(self.view.bounds);

If the view is not being auto-rotated by the View Controller then you will need to check the interface orientation to determine which part of the view bounds represents the 'width' and the 'height'. Note that the frame property will give you the rect of the view in the UIWindow's coordinate space which (by default) won't be taking the interface orientation into account.

Base 64 encode and decode example code

For API level 26+

String encodedString = Base64.getEncoder().encodeToString(byteArray);


Is it better practice to use String.format over string Concatenation in Java?

Here's the same test as above with the modification of calling the toString() method on the StringBuilder. The results below show that the StringBuilder approach is just a bit slower than String concatenation using the + operator.


class StringTest {

  public static void main(String[] args) {

    String formatString = "Hi %s; Hi to you %s";

    long start = System.currentTimeMillis();
    for (int i = 0; i < 1000000; i++) {
        String s = String.format(formatString, i, +i * 2);

    long end = System.currentTimeMillis();
    System.out.println("Format = " + ((end - start)) + " millisecond");

    start = System.currentTimeMillis();

    for (int i = 0; i < 1000000; i++) {
        String s = "Hi " + i + "; Hi to you " + i * 2;

    end = System.currentTimeMillis();

    System.out.println("Concatenation = " + ((end - start)) + " millisecond");

    start = System.currentTimeMillis();

    for (int i = 0; i < 1000000; i++) {
        StringBuilder bldString = new StringBuilder("Hi ");
        bldString.append(i).append("Hi to you ").append(i * 2).toString();

    end = System.currentTimeMillis();

    System.out.println("String Builder = " + ((end - start)) + " millisecond");


Shell Commands : (compile and run StringTest 5 times)

> javac
> sh -c "for i in \$(seq 1 5); do echo \"Run \${i}\"; java StringTest; done"

Results :

Run 1
Format = 1290 millisecond
Concatenation = 115 millisecond
String Builder = 130 millisecond

Run 2
Format = 1265 millisecond
Concatenation = 114 millisecond
String Builder = 126 millisecond

Run 3
Format = 1303 millisecond
Concatenation = 114 millisecond
String Builder = 127 millisecond

Run 4
Format = 1297 millisecond
Concatenation = 114 millisecond
String Builder = 127 millisecond

Run 5
Format = 1270 millisecond
Concatenation = 114 millisecond
String Builder = 126 millisecond

Tool for sending multipart/form-data request

The usual error is one tries to put Content-Type: {multipart/form-data} into the header of the post request. That will fail, it is best to let Postman do it for you. For example:

Suggestion To Load Via Postman Body Part

Fails If In Header Common Error

Works should remove content type from the Header

How to run ssh-add on windows?

The Git GUI for Windows has a window-based application that allows you to paste in locations for ssh keys and repo url etc:

Postgresql 9.2 pg_dump version mismatch

For me the issue was updating psql apt-get wasn't resolving newer versions, even after update. The following worked.


Start with the import of the GPG key for PostgreSQL packages.

sudo apt-get install wget ca-certificates
wget --quiet -O - | sudo apt-key add -

Now add the repository to your system.

sudo sh -c 'echo "deb `lsb_release -cs`-pgdg main" >> /etc/apt/sources.list.d/pgdg.list'

Install PostgreSQL on Ubuntu

sudo apt-get update
sudo apt-get install postgresql postgresql-contrib

Putting HTML inside Html.ActionLink(), plus No Link Text?

Just use Url.Action instead of Html.ActionLink:

<li id="home_nav"><a href="<%= Url.Action("ActionName") %>"><span>Span text</span></a></li>

HTML5 phone number validation with pattern

Try this code:

<input type="text" name="Phone Number" pattern="[7-9]{1}[0-9]{9}" 
       title="Phone number with 7-9 and remaing 9 digit with 0-9">

This code will inputs only in the following format:

9238726384 (starting with 9 or 8 or 7 and other 9 digit using any number)

Incorrect format:
2937389471(starting not with 9 or 8 or 7)
32796432796(more than 10 digit)
921543(less than 10 digit)

How to restart a windows service using Task Scheduler

Instead of using a bat file, you can simply create a Scheduled Task. Most of the time you define just one action. In this case, create two actions with the NET command. The first one to stop the service, the second one to start the service. Give them a STOP and START argument, followed by the service name.

In this example we restart the Printer Spooler service.

NET STOP "Print Spooler" 
NET START "Print Spooler"

enter image description here

enter image description here

Note: unfortunately NET RESTART <service name> does not exist.


Linq to sql has no support for Count(Distinct ...). You therefore have to map a .NET method in code onto a Sql server function (thus Count(distinct.. )) and use that.

btw, it doesn't help if you post pseudo code copied from a toolkit in a format that's neither VB.NET nor C#.

How do I ignore files in a directory in Git?

The first one. Those file paths are relative from where your .gitignore file is.

SQL How to remove duplicates within select query?

here is the solution for your query returning only one row for each date in that table here in the solution 'tony' will occur twice as two different start dates are there for it


How to get text in QlineEdit when QpushButton is pressed in a string?

The object name is not very important. what you should be focusing at is the variable that stores the lineedit object (le) and your pushbutton object(pb)

QObject(self.pb, SIGNAL("clicked()"), self.button_clicked)

def button_clicked(self):

I think this is what you want. I hope i got your question correctly :)

SQL Server equivalent to MySQL enum data type?

It doesn't. There's a vague equivalent:

mycol VARCHAR(10) NOT NULL CHECK (mycol IN('Useful', 'Useless', 'Unknown'))

if else statement in AngularJS templates

In the latest version of Angular (as of 1.1.5), they have included a conditional directive called ngIf. It is different from ngShow and ngHide in that the elements aren't hidden, but not included in the DOM at all. They are very useful for components which are costly to create but aren't used:

<div ng-if="video == video.large">
    <!-- code to render a large video block-->
<div ng-if="video != video.large">
    <!-- code to render the regular video block -->

MongoDB Data directory /data/db not found

MongoDB needs data directory to store data. Default path is /data/db

When you start MongoDB engine, it searches this directory which is missing in your case. Solution is create this directory and assign rwx permission to user.

If you want to change the path of your data directory then you should specify it while starting mongod server like,

mongod --dbpath /data/<path> --port <port no> 

This should help you start your mongod server with custom path and port.

python and sys.argv

BTW you can pass the error message directly to sys.exit:

if len(sys.argv) < 2:
    sys.exit('Usage: %s database-name' % sys.argv[0])

if not os.path.exists(sys.argv[1]):
    sys.exit('ERROR: Database %s was not found!' % sys.argv[1])

How to: "Separate table rows with a line"


<table cellspacing="0">
  <tr class="top bottom row">
    <td>one one</td>
    <td>one two</td>
  <tr class="top bottom row">
    <td>two one</td>
    <td>two two</td>
  <tr class="top bottom row">
    <td>three one</td>
    <td>three two</td>


CSS: td { border-top: thin solid black; }
tr.bottom td { border-bottom: thin solid black; }
tr.row td:first-child { border-left: thin solid black; }
tr.row td:last-child { border-right: thin solid black; }?


Adding css class through aspx code behind

Assuming your div has some CSS classes already...

<div id="classMe" CssClass="first"></div>

The following won't replace existing definitions:

ClassMe.CssClass += " second";

And if you are not sure until the very last moment...

string classes = ClassMe.CssClass;
ClassMe.CssClass += (classes == "") ? "second" : " second";

Twitter bootstrap remote modal shows same content every time

For bootstrap 3 you should use:

$('body').on('', '.modal', function () {

Error message "unreported exception; must be caught or declared to be thrown"

Exceptions bubble up the stack. If a caller calls a method that throws a checked exception, like IOException, it must also either catch the exception, or itself throw it.

In the case of the first block:

    setSize(300, 300);

        addWindowListener(new WindowAdapter()
            public void windowClosing(WindowEvent we)

You would have to include a try catch block:

    try {
    catch (IOException e) {
        // Do something here
    setSize(300, 300);

        addWindowListener(new WindowAdapter()
            public void windowClosing(WindowEvent we)

In the case of the second:

public void actionPerformed(ActionEvent ae)
    if (ae.getSource() == submit)

You cannot throw IOException from this method as its signature is determined by the interface, so you must catch the exception within:

public void actionPerformed(ActionEvent ae)
        try {
        catch (IOException e) {
            // Do something here

Remember, the showFile() method is throwing the exception; that's what the "throws" keyword indicates that the method may throw that exception. If the showFile() method is throwing, then whatever code calls that method must catch, or themselves throw the exception explicitly by including the same throws IOException addition to the method signature, if it's permitted.

If the method is overriding a method signature defined in an interface or superclass that does not also declare that the method may throw that exception, you cannot declare it to throw an exception.

How to add elements of a Java8 stream into an existing List

Lets say we have existing list, and gonna use java 8 for this activity `

import java.util.*;

public class AddingArray {

    public void addArrayInList(){
        List<Integer> list = Arrays.asList(3, 7, 9);

   // And we have an array of Integer type 

        int nums[] = {4, 6, 7};

   //Now lets add them all in list
   // converting array to a list through stream and adding that list to previous list
        list.addAll( -> 


How to check if JavaScript object is JSON

If you are trying to check the type of an object after you parse a JSON string, I suggest checking the constructor attribute:

obj.constructor == Array || obj.constructor == String || obj.constructor == Object

This will be a much faster check than typeof or instanceof.

If a JSON library does not return objects constructed with these functions, I would be very suspiciouse of it.

TortoiseGit save user authentication / credentials

[open git settings (TortoiseGit ? Settings ? Git)][1]

[In GIt: click to edit global .gitconfig][2]

config username and password

JAXB: How to ignore namespace during unmarshalling XML document?

In my situation, I have many namespaces and after some debug I find another solution just changing the NamespaceFitler class. For my situation (just unmarshall) this work fine.

 import javax.xml.namespace.QName;
 import org.xml.sax.Attributes;
 import org.xml.sax.ContentHandler;
 import org.xml.sax.SAXException;
 import org.xml.sax.helpers.XMLFilterImpl;
 import com.sun.xml.bind.v2.runtime.unmarshaller.SAXConnector;

 public class NamespaceFilter extends XMLFilterImpl {
    private SAXConnector saxConnector;

    public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {
        if(saxConnector != null) {
            Collection<QName> expected = saxConnector.getContext().getCurrentExpectedElements();
            for(QName expectedQname : expected) {
                if(localName.equals(expectedQname.getLocalPart())) {
                    super.startElement(expectedQname.getNamespaceURI(), localName, qName, atts);
        super.startElement(uri, localName, qName, atts);

    public void setContentHandler(ContentHandler handler) {
        if(handler instanceof SAXConnector) {
            saxConnector = (SAXConnector) handler;

random.seed(): What does it do?

Seed() can be used for later use ---

>>> import numpy as np
>>> np.random.seed(12)
>>> np.random.rand(4)
array([0.15416284, 0.7400497 , 0.26331502, 0.53373939])
>>> np.random.seed(10)
>>> np.random.rand(4)
array([0.77132064, 0.02075195, 0.63364823, 0.74880388])
>>> np.random.seed(12) # When you use same seed as before you will get same random output as before
>>> np.random.rand(4)
array([0.15416284, 0.7400497 , 0.26331502, 0.53373939])
>>> np.random.seed(10)
>>> np.random.rand(4)
array([0.77132064, 0.02075195, 0.63364823, 0.74880388])

Passing command line arguments in Visual Studio 2010?

  • Right click your project in Solution Explorer and select Properties from the menu
  • Go to Configuration Properties -> Debugging
  • Set the Command Arguments in the property list.

Adding Command Line Arguments

ES6 Map in Typescript

EDIT (Jun 5 2019): While the idea that "TypeScript supports Map natively" is still true, since version 2.1 TypeScript supports something called Record.

type MyMapLikeType = Record<string, IPerson>;
const peopleA: MyMapLikeType = {
    "a": { name: "joe" },
    "b": { name: "bart" },

Unfortunately the first generic parameter (key type) is still not fully respected: even with a string type, something like peopleA[0] (a number) is still valid.

EDIT (Apr 25 2016): The answer below is old and should not be considered the best answer. TypeScript does support Maps "natively" now, so it simply allows ES6 Maps to be used when the output is ES6. For ES5, it does not provide polyfills; you need to embed them yourself.

For more information, refer to mohamed hegazy's answer below for a more modern answer, or even this reddit comment for a short version.

As of 1.5.0 beta, TypeScript does not yet support Maps. It is not yet part of the roadmap, either.

The current best solution is an object with typed key and value (sometimes called a hashmap). For an object with keys of type string, and values of type number:

var arr : { [key:string]:number; } = {};

Some caveats, however:

  1. keys can only be of type string or number
  2. It actually doesn't matter what you use as the key type, since numbers/strings are still accepted interchangeably (only the value is enforced).

With the above example:

// OK:
arr["name"] = 1; // String key is fine
arr[0] = 0; // Number key is fine too

// Not OK:
arr[{ a: "a" }] = 2; // Invalid key
arr[3] = "name"; // Invalid value

Best way to include CSS? Why use @import?

I experienced a "high peak" of linked stylesheets you can add. While adding any number of linked Javascript wasn't a problem for my free host provider, after doubling number of external stylesheets I got a crash/slow down. And the right code example is:

@import 'stylesheetB.css';

So, I find it useful for having a good mental map, as Nitram mentioned, while still at hard-coding the design. Godspeed. And I pardon for English grammatical mistakes, if any.

How do I pass a datetime value as a URI parameter in mvc?

Use the ticks value. It's quite simple to rebuild into a DateTime structure

 Int64 nTicks = DateTime.Now.Ticks;
 DateTime dtTime = new DateTime(nTicks);

How do I do multiple CASE WHEN conditions using SQL Server 2008?

Something Like this, Two Conditions Two Columns

        END) AS ITEMS,
              AS RECIBIDA

How to change a single value in a NumPy array?

Is this what you are after? Just index the element and assign a new value.


array([[ 1,  2,  3,  4],
       [ 5,  6,  7,  8],
       [ 9, 150, 11, 12],
       [13, 14, 15, 16]])

phpMyAdmin is throwing a #2002 cannot log in to the mysql server phpmyadmin

Did you set up the MySQL on your machine? It sounds like you're using Windows; MySQL runs as a "Service" on your machine (right-click My Computer -> Manage -> Services).

Get week day name from a given month, day and year individually in SQL Server

Tested and works on SQL 2005 and 2008. Not sure if this works in 2012 and later.

The solution uses DATENAME instead of DATEPART

select datename(dw,getdate()) --Thursday
select datepart(dw,getdate()) --2

This is work in sql 2014 also.

Disabling Warnings generated via _CRT_SECURE_NO_DEPRECATE

You can also use the Secure Template Overloads, they will help you replace the unsecure calls with secure ones anywhere it is possible to easily deduce buffer size (static arrays).

Just add the following:


Then fix the remaining warnings by hand, by using the _s functions.