Programs & Examples On #Spring transactions

Questions related to Spring's Transaction API (programmatic or declarative)

How to manually force a commit in a @Transactional method?

I had a similar use case during testing hibernate event listeners which are only called on commit.

The solution was to wrap the code to be persistent into another method annotated with REQUIRES_NEW. (In another class) This way a new transaction is spawned and a flush/commit is issued once the method returns.


Keep in mind that this might influence all the other tests! So write them accordingly or you need to ensure that you can clean up after the test ran.

Spring transaction REQUIRED vs REQUIRES_NEW : Rollback Transaction

If you really need to do it in separate transaction you need to use REQUIRES_NEW and live with the performance overhead. Watch out for dead locks.

I'd rather do it the other way:

  • Validate data on Java side.
  • Run everyting in one transaction.
  • If anything goes wrong on DB side -> it's a major error of DB or validation design. Rollback everything and throw critical top level error.
  • Write good unit tests.

The matching wildcard is strict, but no declaration can be found for element 'tx:annotation-driven'

In my case this was actually a symptom of the server, hosted on AWS, lacking an IP for the external network. It would attempt to download namespaces from and fail to make a connection.

Currency format for display

This kind of functionality is built in.

When using a decimal you can use a format string "C" or "c".

decimal dec = 123.00M;
string uk = dec.ToString("C", new CultureInfo("en-GB")); // uk holds "£123.00"
string us = dec.ToString("C", new CultureInfo("en-US")); // us holds "$123.00"

Android webview & localStorage

setDatabasePath() method was deprecated in API level 19. I advise you to use storage locale like this:

    webView.getSettings().setDatabasePath("/data/data/" + webView.getContext().getPackageName() + "/databases/");

Does a finally block always get executed in Java?

Finally is always called at the end

when you try, it executes some code, if something happens in try, then catch will catch that exception and you could print some mssg out or throw an error, then finally block is executed.

Finally is normally used when doing cleanups, for instance, if you use a scanner in java, you should probably close the scanner as it leads to other problems such as not being able to open some file

How get permission for camera in android.(Specifically Marshmallow)

You can try the following code to request camera permission in marshmallow. First check if the user grant the permission. If user has not granted the permission, then request the camera permission:

private static final int MY_CAMERA_REQUEST_CODE = 100;

if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
    requestPermissions(new String[]{Manifest.permission.CAMERA}, MY_CAMERA_REQUEST_CODE);

After requesting the permission, dialog will display to ask permission containing allow and deny options. After clicking action we can get result of the request with the following method:

public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if (requestCode == MY_CAMERA_REQUEST_CODE) {
        if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            Toast.makeText(this, "camera permission granted", Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(this, "camera permission denied", Toast.LENGTH_LONG).show();

$watch an object

you must changes in $watch ....

function MyController($scope) {_x000D_
    $scope.form = {_x000D_
        name: 'my name',_x000D_
    $scope.$watch('', function(newVal, oldVal){_x000D_
<script src=""></script>_x000D_
<div ng-app>_x000D_
    <div ng-controller="MyController">_x000D_
        <label>Name:</label> <input type="text" ng-model=""/>_x000D_
            {{ form }}_x000D_

How to get a unique computer identifier in Java (like disk ID or motherboard ID)?

In the java programs I have written for release I used the motherboard serial number (which is what I beleive windows use); however, this only works on windows as my function creates a temporary VB script which uses the WMI to retrieve the value.

public static String getMotherboardSerial() {
      String result = "";
        try {
          File file = File.createTempFile("GetMBSerial",".vbs");
          FileWriter fw = new FileWriter(file);

          String vbs =
             "Set objWMIService = GetObject(\"winmgmts:\\\\.\\root\\cimv2\")\n"
            + "Set colItems = objWMIService.ExecQuery _ \n"
            + "   (\"Select * from Win32_ComputerSystemProduct\") \n"
            + "For Each objItem in colItems \n"
            + "    Wscript.Echo objItem.IdentifyingNumber \n"
            + "Next \n";

          Process gWMI = Runtime.getRuntime().exec("cscript //NoLogo " + file.getPath());
          BufferedReader input = new BufferedReader(new InputStreamReader(gWMI.getInputStream()));
          String line;
          while ((line = input.readLine()) != null) {
             result += line;
        catch(Exception e){
        result = result.trim();
        return result;

How do I fix a .NET windows application crashing at startup with Exception code: 0xE0434352?

If you are getting that error from Event Viewer, you should see another error event (at least one) from the Source ".NET Runtime". Look at that error message as it will contain the Exception info.

SqlBulkCopy - The given value of type String from the data source cannot be converted to type money of the specified target column

@Corey - It just simply strips out all invalid characters. However, your comment made me think of the answer.

The problem was that many of the fields in my database are nullable. When using SqlBulkCopy, an empty string is not inserted as a null value. So in the case of my fields that are not varchar (bit, int, decimal, datetime, etc) it was trying to insert an empty string, which obviously is not valid for that data type.

The solution was to modify my loop where I validate the values to this (repeated for each datatype that is not string)

//--- convert decimal values
foreach (DataColumn DecCol in DecimalColumns)
          dr[DecCol] = null; //--- this had to be set to null, not empty
          dr[DecCol] = Helpers.CleanDecimal(dr[DecCol].ToString());

After making the adjustments above, everything inserts without issues.

Constructor in an Interface?

There is only static fields in interface that dosen't need to initialized during object creation in subclass and the method of interface has to provide actual implementation in subclass .So there is no need of constructor in interface.

Second reason-during the object creation of subclass, the parent constructor is called .But if there will be more than one interface implemented then a conflict will occur during call of interface constructor as to which interface's constructor will call first

Pass Javascript Array -> PHP

So use the client-side loop to build a two-dimensional array of your arrays, and send the entire thing to PHP in one request.

Server-side, you'll need to have another loop which does its regular insert/update for each sub-array.

Checking the equality of two slices

You need to loop over each of the elements in the slice and test. Equality for slices is not defined. However, there is a bytes.Equal function if you are comparing values of type []byte.

func testEq(a, b []Type) bool {

    // If one is nil, the other must also be nil.
    if (a == nil) != (b == nil) { 
        return false; 

    if len(a) != len(b) {
        return false

    for i := range a {
        if a[i] != b[i] {
            return false

    return true

How to Execute SQL Script File in Java?

For my simple project the user should be able to select SQL-files which get executed. As I was not happy with the other answers and I am using Flyway anyway I took a closer look at the Flyway code. DefaultSqlScriptExecutor is doing the actual execution, so I tried to figure out how to create an instance of DefaultSqlScriptExecutor.

Basically the following snippet loads a String splits it into the single statements and executes one by one. Flyway also provides other LoadableResources than StringResource e.g. FileSystemResource. But I have not taken a closer look at them.

As DefaultSqlScriptExecutor and the other classes are not officially documented by Flyway use the code-snippet with care.

public static void execSqlQueries(String sqlQueries, Configuration flyWayConf) throws SQLException {
  // create dependencies FlyWay needs to execute the SQL queries
  JdbcConnectionFactory jdbcConnectionFactory = new JdbcConnectionFactory(flyWayConf.getDataSource(),
  DatabaseType databaseType = jdbcConnectionFactory.getDatabaseType();
  ParsingContext parsingContext = new ParsingContext();
  SqlScriptFactory sqlScriptFactory = databaseType.createSqlScriptFactory(flyWayConf, parsingContext);
  Connection conn = flyWayConf.getDataSource().getConnection();
  JdbcTemplate jdbcTemp = new JdbcTemplate(conn);
  ResourceProvider resProv = flyWayConf.getResourceProvider();
  DefaultSqlScriptExecutor scriptExec = new DefaultSqlScriptExecutor(jdbcTemp, null, false, false, false, null);
  // Prepare and execute the actual queries
  StringResource sqlRes = new StringResource(sqlQueries);
  SqlScript sqlScript = sqlScriptFactory.createSqlScript(sqlRes, true, resProv);

How to make Unicode charset in cmd.exe by default?

Reg file

Windows Registry Editor Version 5.00

Command Prompt

REG ADD HKCU\Console /v CodePage /t REG_DWORD /d 0xfde9


sp -t d HKCU:\Console CodePage 0xfde9


regtool set /user/Console/CodePage 0xfde9

JDK was not found on the computer for NetBeans 6.5

I have same problem, and solve by this way:

  1. Open CMD
  2. Go to file netbeans.exe
  3. Press Shift Key + Right Click and copy as path Copy as path
  4. Paste on CMD look like C:\Users\unnamed>"C:\Users\unnamed\Downloads\Programs\netbeans-8.2-windows.exe"
  5. Write --javahome do same point 2 on JDK folder
  6. Write on cmd look like C:\Users\unnamed>"C:\Users\unnamed\Downloads\Programs\netbeans-8.2-windows.exe" --javahome "C:\Program Files\Java\jdk-9.0.4"

  7. Enter. Enjoy it.

Fastest way to extract frames using ffmpeg?

If the JPEG encoding step is too performance intensive, you could always store the frames uncompressed as BMP images:

ffmpeg -i file.mpg -r 1/1 $filename%03d.bmp

This also has the advantage of not incurring more quality loss through quantization by transcoding to JPEG. (PNG is also lossless but tends to take much longer than JPEG to encode.)

Where does Chrome store extensions?

For older versions of windows (2k, 2k3, xp)

"%Userprofile%\Local Settings\Application Data\Google\Chrome\User Data\Default\Extensions" 

What are Bearer Tokens and token_type in OAuth 2?

token_type is a parameter in Access Token generate call to Authorization server, which essentially represents how an access_token will be generated and presented for resource access calls. You provide token_type in the access token generation call to an authorization server.

If you choose Bearer (default on most implementation), an access_token is generated and sent back to you. Bearer can be simply understood as "give access to the bearer of this token." One valid token and no question asked. On the other hand, if you choose Mac and sign_type (default hmac-sha-1 on most implementation), the access token is generated and kept as secret in Key Manager as an attribute, and an encrypted secret is sent back as access_token.

Yes, you can use your own implementation of token_type, but that might not make much sense as developers will need to follow your process rather than standard implementations of OAuth.

javascript: using a condition in switch case

Your code does not work because it is not doing what you are expecting it to do. Switch blocks take in a value, and compare each case to the given value, looking for equality. Your comparison value is an integer, but most of your case expressions resolve to a boolean value.

So, for example, say liCount = 2. Your first case will not match, because 2 != 0. Your second case, (liCount<=5 && liCount>0) evaluates to true, but 2 != true, so this case will not match either.

For this reason, as many others have said, you should use a series of if...then...else if blocks to do this.

SASS - use variables across multiple files

Create an index.scss and there you can import all file structure you have. I will paste you my index from an enterprise project, maybe it will help other how to structure files in css:

@import 'base/_reset';

@import 'helpers/_variables';
@import 'helpers/_mixins';
@import 'helpers/_functions';
@import 'helpers/_helpers';
@import 'helpers/_placeholders';

@import 'base/_typography';

@import 'pages/_versions';
@import 'pages/_recording';
@import 'pages/_lists';
@import 'pages/_global';

@import 'forms/_buttons';
@import 'forms/_inputs';
@import 'forms/_validators';
@import 'forms/_fieldsets';

@import 'sections/_header';
@import 'sections/_navigation';
@import 'sections/_sidebar-a';
@import 'sections/_sidebar-b';
@import 'sections/_footer';

@import 'vendors/_ui-grid';

@import 'components/_modals';
@import 'components/_tooltip';
@import 'components/_tables';
@import 'components/_datepickers';

And you can watch them with gulp/grunt/webpack etc, like:


// SASS Task

var gulp = require('gulp');
var sass = require('gulp-sass');
//var concat = require('gulp-concat');
var uglifycss = require('gulp-uglifycss');
var sourcemaps = require('gulp-sourcemaps');

gulp.task('styles', function(){
    return gulp
            .pipe(sass().on('error', sass.logError))
                "maxLineLen": 80,
                "uglyComments": true

gulp.task('watch', function () {'sass/**/*.scss', ['styles']);

gulp.task('default', ['watch']);

How to get the current taxonomy term ID (not the slug) in WordPress?

If you are in taxonomy page.

That's how you get all details about the taxonomy.

get_term_by( 'slug', get_query_var( 'term' ), get_query_var( 'taxonomy' ) );

This is how you get the taxonomy id

$termId = get_term_by( 'slug', get_query_var( 'term' ), get_query_var( 'taxonomy' ) )->term_id;

But if you are in post page (taxomony -> child)

$terms = wp_get_object_terms( get_queried_object_id(), 'taxonomy-name');
$term_id = $terms[0]->term_id;

Finding index of character in Swift String

If you think about it, you actually don't really need the exact Int version of the location. The Range or even the String.Index is enough to get the substring out again if needed:

let myString = "hello"

let rangeOfE = myString.rangeOfString("e")

if let rangeOfE = rangeOfE {
    myString.substringWithRange(rangeOfE) // e
    myString[rangeOfE] // e

    // if you do want to create your own range
    // you can keep the index as a String.Index type
    let index = rangeOfE.startIndex
    myString.substringWithRange(Range<String.Index>(start: index, end: advance(index, 1))) // e

    // if you really really need the 
    // Int version of the index:
    let numericIndex = distance(index, advance(index, 1)) // 1 (type Int)

Getting all documents from one collection in Firestore

Here's a simple version of the top answer, but going into an object with the document ids:

async getMarker() {
    const snapshot = await firebase.firestore().collection('events').get()
    return (acc, doc, i) {
              acc[] =;
              return acc;
            }, {});

What is the fastest/most efficient way to find the highest set bit (msb) in an integer in C?

What about

int highest_bit(unsigned int a) {
    int count;
    std::frexp(a, &count);
    return count - 1;


Decoding a Base64 string in Java

Modify the package you're using:

import org.apache.commons.codec.binary.Base64;

And then use it like this:

byte[] decoded = Base64.decodeBase64("YWJjZGVmZw==");
System.out.println(new String(decoded, "UTF-8") + "\n");

MySQL LIMIT on DELETE statement

There is a workaround to solve this problem by using a derived table.

DELETE t1 FROM test t1 JOIN (SELECT FROM test LIMIT 1) t2 ON =

Because the LIMIT is inside the derived table the join will match only 1 row and thus the query will delete only this row.

Show/Hide Table Rows using Javascript classes


Doesn't work in all browsers. Instead you could return false in OnClick event.

onClick="toggle_it('tr1');toggle_it('tr2'); return false;">

Not sure if this is the best way, but I tested in IE, FF and Chrome and its working fine.

How to remove entity with ManyToMany relationship in JPA (and corresponding join table rows)?

For my case, I deleted the mappedBy and joined tables like this:

@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "user_group", joinColumns = {
        @JoinColumn(name = "user", referencedColumnName = "user_id")
}, inverseJoinColumns = {
        @JoinColumn(name = "group", referencedColumnName = "group_id")
private List<User> users;

@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private List<Group> groups;

Moving Panel in Visual Studio Code to right side

For Visual Studio Code v1.31.1, you can toggle the panel session via the View menu.

  • Go to the View Menu.
  • Via the Appearance option, click on Toggle Panel Position

enter image description here

How to install MinGW-w64 and MSYS2?

Unfortunately, the MinGW-w64 installer you used sometimes has this issue. I myself am not sure about why this happens (I think it has something to do with Sourceforge URL redirection or whatever that the installer currently can't handle properly enough).

Anyways, if you're already planning on using MSYS2, there's no need for that installer.

  1. Download MSYS2 from this page (choose 32 or 64-bit according to what version of Windows you are going to use it on, not what kind of executables you want to build, both versions can build both 32 and 64-bit binaries).

  2. After the install completes, click on the newly created "MSYS2 Shell" option under either MSYS2 64-bit or MSYS2 32-bit in the Start menu. Update MSYS2 according to the wiki (although I just do a pacman -Syu, ignore all errors and close the window and open a new one, this is not recommended and you should do what the wiki page says).

  3. Install a toolchain

    a) for 32-bit:

    pacman -S mingw-w64-i686-gcc

    b) for 64-bit:

    pacman -S mingw-w64-x86_64-gcc
  4. install any libraries/tools you may need. You can search the repositories by doing

    pacman -Ss name_of_something_i_want_to_install


    pacman -Ss gsl

    and install using

    pacman -S package_name_of_something_i_want_to_install


    pacman -S mingw-w64-x86_64-gsl

    and from then on the GSL library is automatically found by your MinGW-w64 64-bit compiler!

  5. Open a MinGW-w64 shell:

    a) To build 32-bit things, open the "MinGW-w64 32-bit Shell"

    b) To build 64-bit things, open the "MinGW-w64 64-bit Shell"

  6. Verify that the compiler is working by doing

    gcc -v

If you want to use the toolchains (with installed libraries) outside of the MSYS2 environment, all you need to do is add <MSYS2 root>/mingw32/bin or <MSYS2 root>/mingw64/bin to your PATH.

How to output only captured groups with sed?

It's not what the OP asked for (capturing groups) but you can extract the numbers using:

S='This is a sample 123 text and some 987 numbers'
echo "$S" | sed 's/ /\n/g' | sed -r '/([0-9]+)/ !d'

Gives the following:


Jenkins restrict view of jobs per user

You can install "Extended Read Permission" plug-in. Then in either "Global Settings" or in individual job configuration, you can give the user "Extended Read" permission.

Which .NET Dependency Injection frameworks are worth looking into?

I've used Spring.NET in the past and had great success with it. I never noticed any substantial overhead with it, though the project we used it on was fairly heavy on its own. It only took a little time reading through the documentation to get it set up.

Get root password for Google Cloud Engine VM

I tried "ManiIOT"'s solution and it worked surprisingly. I've added another role (Compute Admin Role) for my google user account from IAM admin. Then stopped and restarted the VM. Afterwards 'sudo passwd' let me to generate a new password for the user.

So here are steps.

  1. Go to IAM & Admin
  2. Select IAM
  3. Find your user name service account (basically your google account) and click Edit-member
  4. Add another role --> select 'Compute Engine' - 'Compute Admin'
  5. Restart your Compute VM
  6. open SSH shell and run the command 'sudo passwd'
  7. enter a brand new password. Voilà!

Responsive css styles on mobile devices ONLY

Why not use a media query range.

I'm currently working on a responsive layout for my employer and the ranges I'm using are as follows:

You have your main desktop styles in the body of the CSS file (1024px and above) and then for specific screen sizes I'm using:

@media all and (min-width:960px) and (max-width: 1024px) {
  /* put your css styles in here */

@media all and (min-width:801px) and (max-width: 959px) {
  /* put your css styles in here */

@media all and (min-width:769px) and (max-width: 800px) {
  /* put your css styles in here */

@media all and (min-width:569px) and (max-width: 768px) {
  /* put your css styles in here */

@media all and (min-width:481px) and (max-width: 568px) {
  /* put your css styles in here */

@media all and (min-width:321px) and (max-width: 480px) {
  /* put your css styles in here */

@media all and (min-width:0px) and (max-width: 320px) {
  /* put your css styles in here */

This will cover pretty much all devices being used - I would concentrate on getting the styling correct for the sizes at the end of the range (i.e. 320, 480, 568, 768, 800, 1024) as for all the others they will just be responsive to the size available.

Also, don't use px anywhere - use em's or %.

Use css gradient over background image

The accepted answer works well. Just for completeness (and since I like it's shortness), I wanted to share how to to it with compass (SCSS/SASS):

  $colorStart: rgba(0,0,0,0);
  $colorEnd: rgba(0,0,0,0.8);
  @include background-image(linear-gradient(to bottom, $colorStart, $colorEnd), url("bg.jpg"));

How can I center an image in Bootstrap?

Since the img is an inline element, Just use text-center on it's container. Using mx-auto will center the container (column) too.

<div class="row">
    <div class="col-4 mx-auto text-center">
        <img src="..">

By default, images are display:inline. If you only want the center the image (and not the other column content), make the image display:block using the d-block class, and then mx-auto will work.

<div class="row">
  <div class="col-4">
    <img class="mx-auto d-block" src="..">


set the width of select2 input (through Angular-ui directive)

Wanted to add my solution here as well. This is similar to Ravindu's answer above.

I added width: 'resolve', as a property within the select2:

        width: 'resolve',

Then I added a min-width property to select2-container with !important:

.select2-container {
    min-width: 100% !important;

On the select element, the style='100px !important;' attribute needed !important to work:

<select class="form-control" style="width: 160px;" id="searchFilter" name="searchfilter[]">

How do I store an array in localStorage?

Just created this:

Storage.setObj('users.albums.sexPistols',{ sid : "My Way", nancy : "Bitch" });
Storage.setObj('users.albums.sexPistols.sid',"Other songs");


How can you represent inheritance in a database?

The 3rd option is to create a "Policy" table, then a "SectionsMain" table that stores all of the fields that are in common across the types of sections. Then create other tables for each type of section that only contain the fields that are not in common.

Deciding which is best depends mostly on how many fields you have and how you want to write your SQL. They would all work. If you have just a few fields then I would probably go with #1. With "lots" of fields I would lean towards #2 or #3.

Populate data table from data reader

You can load a DataTable directly from a data reader using the Load() method that accepts an IDataReader.

var dataReader = cmd.ExecuteReader();
var dataTable = new DataTable();

Rotation of 3D vector?

It can also be solved using quaternion theory:

def angle_axis_quat(theta, axis):
    Given an angle and an axis, it returns a quaternion.
    axis = np.array(axis) / np.linalg.norm(axis)
    return np.append([np.cos(theta/2)],np.sin(theta/2) * axis)

def mult_quat(q1, q2):
    Quaternion multiplication.
    q3 = np.copy(q1)
    q3[0] = q1[0]*q2[0] - q1[1]*q2[1] - q1[2]*q2[2] - q1[3]*q2[3]
    q3[1] = q1[0]*q2[1] + q1[1]*q2[0] + q1[2]*q2[3] - q1[3]*q2[2]
    q3[2] = q1[0]*q2[2] - q1[1]*q2[3] + q1[2]*q2[0] + q1[3]*q2[1]
    q3[3] = q1[0]*q2[3] + q1[1]*q2[2] - q1[2]*q2[1] + q1[3]*q2[0]
    return q3

def rotate_quat(quat, vect):
    Rotate a vector with the rotation defined by a quaternion.
    # Transfrom vect into an quaternion 
    vect = np.append([0],vect)
    # Normalize it
    norm_vect = np.linalg.norm(vect)
    vect = vect/norm_vect
    # Computes the conjugate of quat
    quat_ = np.append(quat[0],-quat[1:])
    # The result is given by: quat * vect * quat_
    res = mult_quat(quat, mult_quat(vect,quat_)) * norm_vect
    return res[1:]

v = [3, 5, 0]
axis = [4, 4, 1]
theta = 1.2 

print(rotate_quat(angle_axis_quat(theta, axis), v))
# [2.74911638 4.77180932 1.91629719]

How to display hexadecimal numbers in C?

i use it like this:

printf("my number is 0x%02X\n",number);
// output: my number is 0x4A

Just change number "2" to any number of chars You want to print ;)

What is the reason for java.lang.IllegalArgumentException: No enum const class even though iterating through values() works just fine?

I had parsing enum problem when i was trying to pass Nullable Enum that we get from Backend. Of course it was working when we get value, but it was problem when the null comes up.

java.lang.IllegalArgumentException: No enum constant

Also the problem was when we at Parcelize read moment write some short if.

My solution for this was

1.Create companion object with parsing method.

enum class CarsType {
    @Json(name = "SMALL")
    @Json(name = "BIG")

    companion object {
        fun nullableValueOf(name: String?) = when (name) {
            null -> null
            else -> valueOf(name)

2. In Parcerable read place use it like this

data class CarData(
    val carId: String? = null,
    val carType: CarsType?,
    val data: String?
) : Parcelable {
    constructor(parcel: Parcel) : this(

Mocking Logger and LoggerFactory with PowerMock and Mockito

In answer to your first question, it should be as simple as replacing:




Regarding your second question (and possibly the puzzling behavior with the first), I think the problem is that logger is static. So,

private static Logger logger = LoggerFactory.getLogger(GoodbyeController.class);

is executed when the class is initialized, not the when the object is instantiated. Sometimes this can be at about the same time, so you'll be OK, but it's hard to guarantee that. So you set up LoggerFactory.getLogger to return your mock, but the logger variable may have already been set with a real Logger object by the time your mocks are set up.

You may be able to set the logger explicitly using something like ReflectionTestUtils (I don't know if that works with static fields) or change it from a static field to an instance field. Either way, you don't need to mock LoggerFactory.getLogger because you'll be directly injecting the mock Logger instance.

Arrays.fill with multidimensional array in Java

double[][] arr = new double[20][4];
Arrays.fill(arr[0], 0);
Arrays.fill(arr[1], 0);
Arrays.fill(arr[2], 0);
Arrays.fill(arr[3], 0);
Arrays.fill(arr[4], 0);
Arrays.fill(arr[5], 0);
Arrays.fill(arr[6], 0);
Arrays.fill(arr[7], 0);
Arrays.fill(arr[8], 0);
Arrays.fill(arr[9], 0);
Arrays.fill(arr[10], 0);
Arrays.fill(arr[11], 0);
Arrays.fill(arr[12], 0);
Arrays.fill(arr[13], 0);
Arrays.fill(arr[14], 0);
Arrays.fill(arr[15], 0);
Arrays.fill(arr[16], 0);
Arrays.fill(arr[17], 0);
Arrays.fill(arr[18], 0);
Arrays.fill(arr[19], 0);

Adding attribute in jQuery

use this code <script> $('#someid').attr('disabled,'true'); </script>

How to add an existing folder with files to SVN?

I don't use commands. You should be able to do this using the GUI:

  • Right-click an empty space in your My Documents folder, select TortoiseSVN > Repo-browser.
  • Enter http://subversion... (your URL path to your Subversion server/directory you will save to) as your path and select OK
  • Right-click the root directory in Repo and select Add folder. Give it the name of your project and create it.
  • Right-click the project folder in the Repo-browser and select Checkout. The Checkout directory will be your Visual Studio\Projects\{your project} folder. Select OK.
  • You will receive a warning that the folder is not empty. Say Yes to checkout/export to that folder - it will not overwrite your project files.
  • Open your project folder. You will see question marks on folders that are associated with your VS project that have not yet been added to Subversion. Select those folders using Ctrl + Click, then right-click one of the selected items and select TortoiseSVN > Add
  • Select OK on the prompt
  • Your files should add. Select OK on the Add Finished! dialog
  • Right-click in an empty area of the folder and select Refresh. You’ll see “+” icons on the folders/files, now
  • Right-click an empty area in the folder once again and select SVN Commit
  • Add a message regarding what you are committing and click OK

Recursively counting files in a Linux directory

find -type f | wc -l

OR (If directory is current directory)

find . -type f | wc -l

How can I enable auto complete support in Notepad++?

Open Notepad++ and Settings -> Preferences -> Auto-Completion -> Check the Auto-insert options you want. this link will help alot:

UTF-8 text is garbled when form is posted as multipart/form-data

I'm using org.apache.commons.fileupload.servlet.ServletFileUpload.ServletFileUpload(FileItemFactory) and defining the encoding when reading out parameter value:

List<FileItem> items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);

for (FileItem item : items) {
    String fieldName = item.getFieldName();

    if (item.isFormField()) {
        String fieldValue = item.getString("UTF-8"); // <-- HERE

Go: panic: runtime error: invalid memory address or nil pointer dereference

According to the docs for func (*Client) Do:

"An error is returned if caused by client policy (such as CheckRedirect), or if there was an HTTP protocol error. A non-2xx response doesn't cause an error.

When err is nil, resp always contains a non-nil resp.Body."

Then looking at this code:

res, err := client.Do(req)
defer res.Body.Close()

if err != nil {
    return nil, err

I'm guessing that err is not nil. You're accessing the .Close() method on res.Body before you check for the err.

The defer only defers the function call. The field and method are accessed immediately.

So instead, try checking the error immediately.

res, err := client.Do(req)

if err != nil {
    return nil, err
defer res.Body.Close()

How can I provide multiple conditions for data trigger in WPF?

To elaborate on @serine's answer and illustrate working with non-trivial multi-valued condition: I had a need to show a "dim-out" overlay on an item for the boolean condition NOT a AND (b OR NOT c).

For background, this is a "Multiple Choice" question. If the user picks a wrong answer it becomes disabled (dimmed out and cannot be selected again). An automated agent has the ability to focus on any particular choice to give an explanation (border highlighted). When the agent focuses on an item, it should not be dimmed out even if it is disabled. All items that are not in focused are marked de-focused, and should be dimmed out.

The logic for dimming is thus:

NOT IsFocused AND (IsDefocused OR NOT Enabled)

To implement this logic, I made a generic IMultiValueConverter named (awkwardly) to match my logic

// 'P' represents a parenthesis
//     !  a &&  ( b ||  !  c )
class NOT_a_AND_P_b_OR_NOT_c_P : IMultiValueConverter
    // redacted [...] for brevity
    public object Convert(object[] values, ...)
        bool a = System.Convert.ToBoolean(values[0]);
        bool b = System.Convert.ToBoolean(values[1]);
        bool c = System.Convert.ToBoolean(values[2]);

        return !a && (b || !c);

In the XAML I use this in a MultiDataTrigger in a <Style><Style.Triggers> resource

        <!-- when the equation is TRUE ... -->
        <Condition Value="True">
                <MultiBinding Converter="{StaticResource NOT_a_AND_P_b_OR_NOT_c_P}">
                    <!-- NOT IsFocus AND ( IsDefocused OR NOT Enabled ) -->
                    <Binding Path="IsFocus"/>
                    <Binding Path="IsDefocused" />
                    <Binding Path="Enabled" />
        <!-- ... show the 'dim-out' overlay -->
        <Setter Property="Visibility" Value="Visible" />

And for completeness sake, my converter is defined in a ResourceDictionary

<ResourceDictionary xmlns:conv="clr-namespace:My.Converters" ...>
    <conv:NOT_a_AND_P_b_OR_NOT_c_P x:Key="NOT_a_AND_P_b_OR_NOT_c_P" />

Auto number column in SharePoint list

You can't add a new unique auto-generated ID to a SharePoint list, but there already is one there! If you edit the "All Items" view you will see a list of columns that do not have the display option checked.

There are quite a few of these columns that exist but that are never displayed, like "Created By" and "Created". These fields are used within SharePoint, but they are not displayed by default so as not to clutter up the display. You can't edit these fields, but you can display them to the user. if you check the "Display" box beside the ID field you will get a unique and auto-generated ID field displayed in your list.

Check out: Unique ID in SharePoint list

Redirect all to index.php using htaccess

You can use something like this:

RewriteEngine on
RewriteRule ^.+$ /index.php [L]

This will redirect every query to the root directory's index.php. Note that it will also redirect queries for files that exist, such as images, javascript files or style sheets.

Set selected option of select box

// Make option have a "selected" attribute using jQuery

var yourValue = "Gateway 2";

$("#gate").find('option').each(function( i, opt ) {
    if( opt.value === yourValue ) 
        $(opt).attr('selected', 'selected');

Text blinking jQuery

I was going to post the steps-timed polyfill, but then I remembered that I really don’t want to ever see this effect, so…

function blink(element, interval) {
    var visible = true;

    setInterval(function() {
        visible = !visible; = visible ? "visible" : "hidden";
    }, interval || 1000);

Using a PagedList with a ViewModel ASP.Net MVC

The fact that you're using a view model has no bearing. The standard way of using PagedList is to store "one page of items" as a ViewBag variable. All you have to determine is what collection constitutes what you'll be paging over. You can't logically page multiple collections at the same time, so assuming you chose Instructors:

ViewBag.OnePageOfItems = myViewModelInstance.Instructors.ToPagedList(pageNumber, 10);

Then, the rest of the standard code works as it always has.

How to remove an element from the flow?

Try to use this:

position: relative;
clear: both;

I use it when I can't use absolute position, for example in printing when you use page-break-after: always; works fine only with position:relative.

jQuery Validate Plugin - Trigger validation of single field

This method seems to do what you want:


Android. Fragment getActivity() sometimes returns null

In Kotlin you can try this way to handle getActivity() null condition.

   activity.let { // activity == getActivity() in java

        //your code here


It will check activity is null or not and if not null then execute inner code.

Make button width fit to the text

If you are developing to a modern browser.

You can use:

width: fit-content;

AndroidStudio: Failed to sync Install build tools

I faced the same issue today,

And solved it easily by following points

1) Start the StandAlone SDK manager (To open the standalone sdk manager - Tools>Android>SDKManager> at Bottom YOu will see a link to launch StandAlone SDK manager)

2) Delete tha package of SDK Build Tools that you have already installed for e.g 24.0.0 rc4.

3) Close the standalone SDK manager then Restart Android Studio.

4) Once after restart the gradle will start building the project and you will get an alert download the package of SDK build tool and Sync. CLick on that and you will start downloading like that...

I hope this helps

System.Runtime.InteropServices.COMException (0x800A03EC)

Found Answer.......!!!!!!!

Officially Microsoft Office 2003 Interop is not supported on Windows server 2008 by Microsoft.

But after a lot of permutations & combinations with the code and search, we came across one solution which works for our scenario.

The solution is to plug the difference between the way Windows 2003 and 2008 maintains its folder structure, because Office Interop depends on the desktop folder for file open/save intermediately. The 2003 system houses the desktop folder under systemprofile which is absent in 2008.

So when we create this folder on 2008 under the respective hierarchy as indicated below; the office Interop is able to save the file as required. This Desktop folder is required to be created under




This worked for me...

Also do check if .NET 1.1 is installed because its needed by Interop and ot preinstalled by Windows Server 2008

Or you can also Use SaveCopyas() method ist just take onargument as filename string)

Thanks Guys..!

Removing pip's cache?

From documentation at

Starting with v6.0, pip provides an on-by-default cache which functions similarly to that of a web browser. While the cache is on by default and is designed do the right thing by default you can disable the cache and always access PyPI by utilizing the --no-cache-dir option.

How to get a list of all valid IP addresses in a local network?

Install nmap,

sudo apt-get install nmap


nmap -sP 192.168.1.*

or more commonly

nmap -sn

will scan the entire .1 to .254 range

This does a simple ping scan in the entire subnet to see which hosts are online.

Send SMTP email using System.Net.Mail via Exchange Online (Office 365)

Fixed a few typos in the working code above:

MailMessage msg = new MailMessage();
msg.To.Add(new MailAddress("[email protected]", "SomeOne"));
msg.From = new MailAddress("[email protected]", "You");
msg.Subject = "This is a Test Mail";
msg.Body = "This is a test message using Exchange OnLine";
msg.IsBodyHtml = true;

SmtpClient client = new SmtpClient();
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("your user name", "your password");
client.Port = 587; // You can use Port 25 if 587 is blocked (mine is!)
client.Host = "";
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.EnableSsl = true;
    lblText.Text = "Message Sent Succesfully";
catch (Exception ex)
    lblText.Text = ex.ToString();

I have two web applications using the above code and both work fine without any trouble.

Why I can't change directories using "cd"?

You can use . to execute a script in the current shell environment:

. script_name

or alternatively, its more readable but shell specific alias source:

source script_name

This avoids the subshell, and allows any variables or builtins (including cd) to affect the current shell instead.

Table header to stay fixed at the top when user scrolls it out of view with jQuery

Well, I was trying to obtain the same effect without resorting to fixed size columns or having a fixed height for the entire table.

The solution I came up with is a hack. It consists of duplicating the entire table then hiding everything but the header, and making that have a fixed position.


<div id="table-container">
<table id="maintable">
            <td>some really long line here instead</td>
<div id="bottom_anchor"></div>


body { height: 1000px; }


function moveScroll(){
    var scroll = $(window).scrollTop();
    var anchor_top = $("#maintable").offset().top;
    var anchor_bottom = $("#bottom_anchor").offset().top;
    if (scroll>anchor_top && scroll<anchor_bottom) {
    clone_table = $("#clone");
    if(clone_table.length == 0){
        clone_table = $("#maintable").clone();
        clone_table.attr('id', 'clone');
                 'pointer-events': 'none',
        $("#clone thead").css({'visibility':'visible','pointer-events':'auto'});
    } else {

See here:

Edit: updated the code so that the thead can receive pointer events(so buttons and links in the header still work). This fixes the problem reported by luhfluh and Joe M.

New jsfiddle here:

Configure Log4net to write to multiple files

I wanted to log all messages to root logger, and to have a separate log with errors, here is how it can be done:

    <appender name="FileAppender" type="log4net.Appender.FileAppender">
        <file value="allMessages.log" />
        <appendToFile value="true" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date  %-5level %logger  - %message%newline" />

    <appender name="ErrorsFileAppender" type="log4net.Appender.FileAppender">
        <file value="errorsLog.log" />
        <appendToFile value="true" />
        <layout type="log4net.Layout.PatternLayout">
            <conversionPattern value="%date  %-5level %logger  - %message%newline" />
        <filter type="log4net.Filter.LevelRangeFilter">
            <levelMin value="ERROR" />
            <levelMax value="FATAL" />

        <level value="ALL" />
        <appender-ref ref="FileAppender" />
        <appender-ref ref="ErrorsFileAppender" />

Notice the use of filter element.

Postgres ERROR: could not open file for reading: Permission denied

Copy your CSV file into the /tmp folder

Files named in a COPY command are read or written directly by the server, not by the client application. Therefore, they must reside on or be accessible to the database server machine, not the client. They must be accessible to and readable or writable by the PostgreSQL user (the user ID the server runs as), not the client. COPY naming a file is only allowed to database superusers, since it allows reading or writing any file that the server has privileges to access.

Set default syntax to different filetype in Sublime Text 2

In the current version of Sublime Text 2 (Build: 2139), you can set the syntax for all files of a certain file extension using an option in the menu bar. Open a file with the extension you want to set a default for and navigate through the following menus: View -> Syntax -> Open all with current extension as... ->[your syntax choice].

Updated 2012-06-28: Recent builds of Sublime Text 2 (at least since Build 2181) have allowed the syntax to be set by clicking the current syntax type in the lower right corner of the window. This will open the syntax selection menu with the option to Open all with current extension as... at the top of the menu.

Updated 2016-04-19: As of now, this also works for Sublime Text 3.

enable cors in .htaccess

I tried @abimelex solution, but in Slim 3.0, mapping the OPTIONS requests goes like:

$app = new \Slim\App();
$app->options('/books/{id}', function ($request, $response, $args) {
    // Return response headers

How can I run specific migration in laravel

use this command php artisan migrate --path=/database/migrations/my_migration.php it worked for me..

Generating 8-character only UUIDs

You can try RandomStringUtils class from apache.commons:

import org.apache.commons.lang3.RandomStringUtils;

final int SHORT_ID_LENGTH = 8;

// all possible unicode characters
String shortId = RandomStringUtils.random(SHORT_ID_LENGTH);

Please keep in mind, that it will contain all possible characters which is neither URL nor human friendly.

So check out other methods too:

// HEX: 0-9, a-f. For example: 6587fddb, c0f182c1
shortId = RandomStringUtils.random(8, "0123456789abcdef"); 

// a-z, A-Z. For example: eRkgbzeF, MFcWSksx
shortId = RandomStringUtils.randomAlphabetic(8); 

// 0-9. For example: 76091014, 03771122
shortId = RandomStringUtils.randomNumeric(8); 

// a-z, A-Z, 0-9. For example: WRMcpIk7, s57JwCVA
shortId = RandomStringUtils.randomAlphanumeric(8); 

As others said probability of id collision with smaller id can be significant. Check out how birthday problem applies to your case. You can find nice explanation how to calculate approximation in this answer.

How make background image on newsletter in outlook?

Background image is not supported in Outlook. You have to use an image and position it behind the text using position relative or absolute.

How to draw a graph in LaTeX?

Aside from the (excellent) suggestion to use TikZ, you could use gastex. I used this before TikZ was available and it did its job too.

How do I get AWS_ACCESS_KEY_ID for Amazon?

Amazon changes the admin console from time to time, hence the previous answers above are irrelevant in 2020.

The way to get the secret access key (Oct.2020) is:

  1. go to IAM console:
  2. click on "Users". (see image) enter image description here
  3. go to the user you need his access key. enter image description here

As i see the answers above, I can assume my answer will become irrelevant in a year max :-)


SQL - Create view from multiple tables

Thanks for the help. This is what I ended up doing in order to make it work.

    SELECT *

Proper use of mutexes in Python

This is the solution I came up with:

import time
from threading import Thread
from threading import Lock

def myfunc(i, mutex):
    print "Thread: %d" %i

mutex = Lock()
for i in range(0,10):
    t = Thread(target=myfunc, args=(i,mutex))
    print "main loop %d" %i


main loop 0
main loop 1
main loop 2
main loop 3
main loop 4
main loop 5
main loop 6
main loop 7
main loop 8
main loop 9
Thread: 0
Thread: 1
Thread: 2
Thread: 3
Thread: 4
Thread: 5
Thread: 6
Thread: 7
Thread: 8
Thread: 9

How to include file in a bash shell script

In my situation, in order to include from the same directory in, I had to do something as follows.

. ./

Not sure why the ./ and not directly. The content of is as follows.

RED=`tput setaf 1`
GREEN=`tput setaf 2`
BLUE=`tput setaf 4`
BOLD=`tput bold`
RESET=`tput sgr0`

Making use of File does not error but, the color do not display. I have tested this in Ubuntu 18.04 and the Bash version is:

GNU bash, version 4.4.19(1)-release (x86_64-pc-linux-gnu)

How to call controller from the button click in MVC 4

You are mixing razor and aspx syntax,if your view engine is razor just do this:

<button class="btn btn-info" type="button" id="addressSearch"   
          onclick="location.href='@Url.Action("List", "Search")'">

Add bottom line to view in SwiftUI / Swift / Objective-C / Xamarin

In SwiftUI, The simplest implementation would be,

struct MyTextField: View {
  var myPlaceHolder: String
  @Binding var text: String

  var underColor: Color
  var height: CGFloat

  var body: some View {
    VStack {
        TextField(self.myPlaceHolder, text: $text)
        .padding(.horizontal, 24)

        Rectangle().frame(height: self.height)
            .padding(.horizontal, 24).foregroundColor(self.underColor)


MyTextField(myPlaceHolder: "PlaceHolder", text: self.$text, underColor: .red, height: 3)

Example Implementation

How to check list A contains any value from list B?

I've profiled Justins two solutions. a.Any(a => b.Contains(a)) is fastest.

using System;
using System.Collections.Generic;
using System.Linq;

namespace AnswersOnSO
    public class Class1
        public static void Main(string []args)
//            How to check if list A contains any value from list B?
//            e.g. something like A.contains(a=> =
            var a = new List<int> {1,2,3,4};
            var b = new List<int> {2,5};
            var times = 10000000;

            DateTime dtAny = DateTime.Now;
            for (var i = 0; i < times; i++)
                var aContainsBElements = a.Any(b.Contains);
            var timeAny = (DateTime.Now - dtAny).TotalSeconds;

            DateTime dtIntersect = DateTime.Now;
            for (var i = 0; i < times; i++)
                var aContainsBElements = a.Intersect(b).Any();
            var timeIntersect = (DateTime.Now - dtIntersect).TotalSeconds;

            // timeAny: 1.1470656 secs
            // timeIn.: 3.1431798 secs

Do HttpClient and HttpClientHandler have to be disposed between requests?

In my understanding, calling Dispose() is necessary only when it's locking resources you need later (like a particular connection). It's always recommended to free resources you're no longer using, even if you don't need them again, simply because you shouldn't generally be holding onto resources you're not using (pun intended).

The Microsoft example is not incorrect, necessarily. All resources used will be released when the application exits. And in the case of that example, that happens almost immediately after the HttpClient is done being used. In like cases, explicitly calling Dispose() is somewhat superfluous.

But, in general, when a class implements IDisposable, the understanding is that you should Dispose() of its instances as soon as you're fully ready and able. I'd posit this is particularly true in cases like HttpClient wherein it's not explicitly documented as to whether resources or connections are being held onto/open. In the case wherein the connection will be reused again [soon], you'll want to forgo Dipose()ing of it -- you're not "fully ready" in that case.

See also: IDisposable.Dispose Method and When to call Dispose

How to set layout_weight attribute dynamically from code?

If you have already defined your view in layout(xml) file and only want to change the weight pro grammatically, then then creating new LayoutParams overwrites other params defined in you xml file.

So first you should use "getLayoutParams" and then setLayoutParams

LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) mButton.getLayoutParams(); params.weight = 4f; mButton.setLayoutParams(params);

Create auto-numbering on images/figures in MS Word

  • Select whole document (Ctrl+A)
  • Press F9
  • Save

Should update the figure caption automatically.

My question is tho, how can one also 'assign' referenced figures '(Fig.4)' in the text to do the same thing - aka change when an image is added above it?

EDIT: Figured it out.. In word go to Insert and Cross-ref and assign the ref. Then Ctrl+A and F9 and everything should sort itself out.

Loop in react-native

You can create render the results (payments) and use a fancy way to iterate over items instead of adding a for loop.

const noGuest = 3;_x000D_
Array(noGuest).fill(noGuest).map(guest => {_x000D_


renderPayments(noGuest) {
  return Array(noGuest).fill(noGuest).map((guess, index) => {
      <View key={index}>
        <View><TextInput /></View>
        <View><TextInput /></View>
        <View><TextInput /></View>

Then use it where you want it

render() {
     const { guest } = this.state;

Hope you got the idea.

If you want to understand this in simple Javascript check Array.prototype.fill()

How can I make a CSS table fit the screen width?

If the table content is too wide (as in this example), there's nothing you can do other than alter the content to make it possible for the browser to show it in a more narrow format. Contrary to the earlier answers, setting width to 100% will have absolutely no effect if the content is too wide (as that link, and this one, demonstrate). Browsers already try to keep tables within the left and right margins if they can, and only resort to a horizontal scrollbar if they can't.

Some ways you can alter content to make a table more narrow:

  • Reduce the number of columns (perhaps breaking one megalithic table into multiple independent tables).
  • If you're using CSS white-space: nowrap on any of the content (or the old nowrap attribute, &nbsp;, a nobr element, etc.), see if you can live without them so the browser has the option of wrapping that content to keep the width down.
  • If you're using really wide margins, padding, borders, etc., try reducing their size (but I'm sure you thought of that).

If the table is too wide but you don't see a good reason for it (the content isn't that wide, etc.), you'll have to provide more information about how you're styling the table, the surrounding elements, etc. Again, by default the browser will avoid the scrollbar if it can.

How to Identify port number of SQL server

  1. Open Run in your system.

  2. Type %windir%\System32\cliconfg.exe

  3. Click on ok button then check that the "TCP/IP Network Protocol Default Value Setup" pop-up is open.

  4. Highlight TCP/IP under the Enabled protocols window.

  5. Click the Properties button.

  6. Enter the new port number, then click OK.

enter image description here

Typescript import/as vs import/require?

import * as express from "express";

This is the suggested way of doing it because it is the standard for JavaScript (ES6/2015) since last year.

In any case, in your tsconfig.json file, you should target the module option to commonjs which is the format supported by nodejs.

Display number with leading zeros

In Python >= 3.6, you can do this succinctly with the new f-strings that were introduced by using:


which prints the variable with name val with a fill value of 0 and a width of 2.

For your specific example you can do this nicely in a loop:

a, b, c = 1, 10, 100
for val in [a, b, c]:

which prints:


For more information on f-strings, take a look at PEP 498 where they were introduced.

Copying one structure to another

Copying by plain assignment is best, since it's shorter, easier to read, and has a higher level of abstraction. Instead of saying (to the human reader of the code) "copy these bits from here to there", and requiring the reader to think about the size argument to the copy, you're just doing a plain assignment ("copy this value from here to here"). There can be no hesitation about whether or not the size is correct.

Also, if the structure is heavily padded, assignment might make the compiler emit something more efficient, since it doesn't have to copy the padding (and it knows where it is), but mempcy() doesn't so it will always copy the exact number of bytes you tell it to copy.

If your string is an actual array, i.e.:

struct {
  char string[32];
  size_t len;
} a, b;

strcpy(a.string, "hello");
a.len = strlen(a.string);

Then you can still use plain assignment:

b = a;

To get a complete copy. For variable-length data modelled like this though, this is not the most efficient way to do the copy since the entire array will always be copied.

Beware though, that copying structs that contain pointers to heap-allocated memory can be a bit dangerous, since by doing so you're aliasing the pointer, and typically making it ambiguous who owns the pointer after the copying operation.

For these situations a "deep copy" is really the only choice, and that needs to go in a function.

Removing input background colour for Chrome autocomplete?

Google Chrome user agent prevent developers' CSS, So for changing autofill UI must use another property like these:

select:-webkit-autofill {
    -webkit-box-shadow: 0 0 0 1000px #d500ff inset !important;
    /*use inset box-shadow to cover background-color*/
    -webkit-text-fill-color: #ffa400 !important;
    /*use text fill color to cover font color*/

Does Python have “private” variables in classes?

About sources (to change the access rights and thus bypass language encapsulation like java or C ++): You don't always have the sources and EVEN if you do, the sources are managed by a system that only allows certain programmers to access a source (in a professional context). Often, every programmer is responsible for certain classes and therefore knows what he can and cannot do. The source manager also locks the sources being modified and of course, manages the access rights of programmers.

So i trust more in software than in human, by experience. So convention is good but MULTIPLE protections are better, like access management (real private variable) + sources management.

How to change the color of the axis, ticks and labels for a plot in matplotlib

motivated by previous contributors, this is an example of three axes.

import matplotlib.pyplot as plt




ax=fig.add_subplot(111, label="1")
ax2=fig.add_subplot(111, label="2", frame_on=False)
ax3=fig.add_subplot(111, label="3", frame_on=False)

ax.plot(x_values1, y_values1, color="C0")
ax.set_xlabel("x label 1", color="C0")
ax.set_ylabel("y label 1", color="C0")
ax.tick_params(axis='x', colors="C0")
ax.tick_params(axis='y', colors="C0")

ax2.scatter(x_values2, y_values2, color="C1")
ax2.set_xlabel('x label 2', color="C1") 
ax2.xaxis.set_label_position('bottom') # set the position of the second x-axis to bottom
ax2.spines['bottom'].set_position(('outward', 36))
ax2.tick_params(axis='x', colors="C1")
ax2.set_ylabel('y label 2', color="C1")       
ax2.tick_params(axis='y', colors="C1")

ax3.plot(x_values3, y_values3, color="C2")
ax3.set_xlabel('x label 3', color='C2')
ax3.spines['bottom'].set_position(('outward', 72))
ax3.tick_params(axis='x', colors='C2')
ax3.set_ylabel('y label 3', color='C2')
ax3.spines['right'].set_position(('outward', 36))
ax3.tick_params(axis='y', colors='C2')

Find oldest/youngest datetime object in a list

Datetimes are comparable; so you can use max(datetimes_list) and min(datetimes_list)

select2 onchange event only works once

Apparently the change event is not fired if a selection already exists when using data. I ended up updating the data manually on select to resolve the problem.

$("#search_code").on("select2-selecting", function(e) {

I know this is pretty late but hopefully this answer will save others time.

How To Auto-Format / Indent XML/HTML in Notepad++

To directly answer the OP, take a look at this guy's site: Thomas Hunter Notepad++ Tidy for XML. Simple steps to follow and you get very nice formatting of your XML right inside NPP. So far the only anomaly I've found is with nested self closing elements EG:

<OuterTag>Text for outer element<SelfClosingTag/></OuterTag>

Will be tidied up to:

<OuterTag>Text for outer element

There may be a way to fix this, but for the time being, it's managed to reduce the number of lines in my document by 300k and this particular anomaly can be worked around.

Add text to textarea - Jquery

That should work. Better if you pass a function to val:

$('#replyBox').val(function(i, text) {
    return text + quote;

This way you avoid searching the element and calling val twice.

How to set selected item of Spinner by value, not by position?

very simple just use getSelectedItem();

eg :

ArrayAdapter<CharSequence> type=ArrayAdapter.createFromResource(this,R.array.admin_typee,android.R.layout.simple_spinner_dropdown_item);

String group=mainType.getSelectedItem().toString();

the above method returns an string value

in the above the R.array.admin_type is an string resource file in values

just create an .xml file in values>>strings

How to hide the soft keyboard from inside a fragment?

Use this:

Button loginBtn = view.findViewById(;
loginBtn.setOnClickListener(new View.OnClickListener() {
   public void onClick(View v) {
      InputMethodManager imm = (InputMethodManager) getActivity().getSystemService(getActivity().INPUT_METHOD_SERVICE);
      imm.hideSoftInputFromWindow(v.getWindowToken(), 0);

Jquery checking success of ajax post

If you need a failure function, you can't use the $.get or $.post functions; you will need to call the $.ajax function directly. You pass an options object that can have "success" and "error" callbacks.

Instead of this:

$.post("/post/url.php", parameters, successFunction);

you would use this:

    url: "/post/url.php",
    type: "POST",
    data: parameters,
    success: successFunction,
    error: errorFunction

There are lots of other options available too. The documentation lists all the options available.

iOS8 Beta Ad-Hoc App Download (itms-services)

Specify a 'display-image' and 'full-size-image' as described here:

iOS8 requires these images

Git push error pre-receive hook declined

Despite the question is specific to gitlab, but similar errors can happen on github, depending how it is set up (usually Github Enterprise).

You need to familiarize yourself with the following concepts:

  • pre-receive hooks
  • organization webhooks
  • Webhooks

Webhooks are more commonly understood than other two items.

The Pre-receive hooks

are scripts that run on the GitHub Enterprise server to enforce policy. When a push occurs, each script runs in an isolated environment to determine whether the push is accepted or rejected.

Organization webhooks:

Webhook events are also sent from your repository to your "organization webhooks". more info.

These are set up in your github enterprise. They are specific to the version of the github enterprise. You may have no visibility because of your access limitations (developer, maintainer, admin, etc).

Zip folder in C#

There's nothing in the BCL to do this for you, but there are two great libraries for .NET which do support the functionality.

I've used both and can say that the two are very complete and have well-designed APIs, so it's mainly a matter of personal preference.

I'm not sure whether they explicitly support adding Folders rather than just individual files to zip files, but it should be quite easy to create something that recursively iterated over a directory and its sub-directories using the DirectoryInfo and FileInfo classes.

Why is Android Studio reporting "URI is not registered"?

I had this problem and for me it was due to creating and manipulating resource files outside Android Studio. I followed the instructions on creating new resource files and folders through Android Studio and solved the problem. You need to create a new Resource File Not directory. It will let you specify or create a directory for you if you need it. If you are creating directories for layouts for different versions, enter the info at the top including the name of the resource file you want to copy to the new folder and select Version and enter the Android version. It will create the appropriate directory with a copy of your resource in it.

Get current rowIndex of table in jQuery

Try this,

   var row_index = $(this).parent().index();
   var col_index = $(this).index();

If you need the index of table contain td then you can change it to

var row_index = $(this).parent('table').index(); 

What is the difference between response.sendRedirect() and request.getRequestDispatcher().forward(request,response)

Simply difference between Forward(ServletRequest request, ServletResponse response) and sendRedirect(String url) is


  1. The forward() method is executed in the server side.
  2. The request is transfer to other resource within same server.
  3. It does not depend on the client’s request protocol since the forward () method is provided by the servlet container.
  4. The request is shared by the target resource.
  5. Only one call is consumed in this method.
  6. It can be used within server.
  7. We cannot see forwarded message, it is transparent.
  8. The forward() method is faster than sendRedirect() method.
  9. It is declared in RequestDispatcher interface.


  1. The sendRedirect() method is executed in the client side.
  2. The request is transfer to other resource to different server.
  3. The sendRedirect() method is provided under HTTP so it can be used only with HTTP clients.
  4. New request is created for the destination resource.
  5. Two request and response calls are consumed.
  6. It can be used within and outside the server.
  7. We can see redirected address, it is not transparent.
  8. The sendRedirect() method is slower because when new request is created old request object is lost.
  9. It is declared in HttpServletResponse.

What is the difference between npm install and npm run build?

  • npm install installs the depedendencies in your package.json config.
  • npm run build runs the script "build" and created a script which runs your application - let's say server.js
  • npm start runs the "start" script which will then be "node server.js"

It's difficult to tell exactly what the issue was but basically if you look at your scripts configuration, I would guess that "build" uses some kind of build tool to create your application while "start" assumes the build has been done but then fails if the file is not there.

You are probably using bower or grunt - I seem to remember that a typical grunt application will have defined those scripts as well as a "clean" script to delete the last build.

Build tools tend to create a file in a bin/, dist/, or build/ folder which the start script then calls - e.g. "node build/server.js". When your npm start fails, it is probably because you called npm clean or similar to delete the latest build so your application file is not present causing npm start to fail.

npm build's source code - to touch on the discussion in this question - is in github for you to have a look at if you like. If you run npm build directly and you have a "build" script defined, it will exit with an error asking you to call your build script as npm run-script build so it's not the same as npm run script.

I'm not quite sure what npm build does, but it seems to be related to postinstall and packaging scripts in dependencies. I assume that this might be making sure that any CLI build scripts's or native libraries required by dependencies are built for the specific environment after downloading the package. This will be why link and install call this script.

Toggle display:none style with JavaScript

You can do this through straight javascript and DOM, but I really recommend learning JQuery. Here is a function you can use to actually toggle that object.

EDIT: Adding the actual code:


HTML snippet:

<a href="#" id="showAll" title="Show Tags">Show All Tags</a>
<ul id="tags" class="subforums" style="display:none;overflow-x: visible; overflow-y: visible; ">
    <li>Tag 1</li>
    <li>Tag 2</li>
    <li>Tag 3</li>
    <li>Tag 4</li>
    <li>Tag 5</li>

Javascript code using JQuery from Google's Content Distribution Network:

$(function() {
    $('#showAll').click(function(){  //Adds click event listener  
        $('#tags').toggle('slow'); // Toggles visibility.  Use the 'slow' parameter to add a nice effect.

You can test directly from this link:

Additional Comments on JQuery:

Someone has suggested that using JQuery for something like this is wrong because it is a 50k Library. I have a strong opinion against that.

JQuery is widely used because of the huge advantages it offers (like many other javascript frameworks). Additionally, JQuery is hosted by Content Distribution Networks (CDNs) like Google's CDN that will guarantee that the library is cached in the client's browser. It will have minimal impact on the client.

Additionally, with JQuery you can use powerful selectors, adding event listener, and use functions that are for the most part guaranteed to be cross-browser.

If you are a beginner and want to learn Javascript, please don't discount frameworks like JQuery. It will make your life so much easier.

Generate a random letter in Python

You can use

map(lambda a : chr(a),  np.random.randint(low=65, high=90, size=4))

Convert double to string

a = 0.000006;
b = 6;
c = a/b;

textbox.Text = c.ToString("0.000000");

As you requested:

textbox.Text = c.ToString("0.######");

This will only display out to the 6th decimal place if there are 6 decimals to display.

How to run Java program in terminal with external library JAR

For compiling the java file having dependency on a jar

javac -cp path_of_the_jar/jarName.jar

For executing the class file

java -cp .;path_of_the_jar/jarName.jar className

It says that TypeError: document.getElementById(...) is null

In your code, you can find this function:

// Update a particular HTML element with a new value
function updateHTML(elmId, value) {
  document.getElementById(elmId).innerHTML = value;

Later on, you call this function with several params:

updateHTML("videoCurrentTime", secondsToHms(ytplayer.getCurrentTime())+' /');
updateHTML("videoDuration", secondsToHms(ytplayer.getDuration()));
updateHTML("bytesTotal", ytplayer.getVideoBytesTotal());
updateHTML("startBytes", ytplayer.getVideoStartBytes());
updateHTML("bytesLoaded", ytplayer.getVideoBytesLoaded());
updateHTML("volume", ytplayer.getVolume());

The first param is used for the "getElementById", but the elements with ID "bytesTotal", "startBytes", "bytesLoaded" and "volume" don't exist. You'll need to create them, since they'll return null.

onclick event function in JavaScript

Check you are calling same function or not.

<script>function greeting(){document.write("hi");}</script>

<input type="button" value="Click Here" onclick="greeting();"/>

Mockito match any class argument

There is another way to do that without cast:


This solution forces the method any() to return Class<A> type and not its default value (Object).

NameError: name 'datetime' is not defined

It can also be used as below:

from datetime import datetime
start_date = datetime(2016,3,1)
end_date = datetime(2016,3,10)

Use .corr to get the correlation between two columns

Without actual data it is hard to answer the question but I guess you are looking for something like this:

Top15['Citable docs per Capita'].corr(Top15['Energy Supply per Capita'])

That calculates the correlation between your two columns 'Citable docs per Capita' and 'Energy Supply per Capita'.

To give an example:

import pandas as pd

df = pd.DataFrame({'A': range(4), 'B': [2*i for i in range(4)]})

   A  B
0  0  0
1  1  2
2  2  4
3  3  6



gives 1 as expected.

Now, if you change a value, e.g.

df.loc[2, 'B'] = 4.5

   A    B
0  0  0.0
1  1  2.0
2  2  4.5
3  3  6.0

the command




which is still close to 1, as expected.

If you apply .corr directly to your dataframe, it will return all pairwise correlations between your columns; that's why you then observe 1s at the diagonal of your matrix (each column is perfectly correlated with itself).


will therefore return

          A         B
A  1.000000  0.995862
B  0.995862  1.000000

In the graphic you show, only the upper left corner of the correlation matrix is represented (I assume).

There can be cases, where you get NaNs in your solution - check this post for an example.

If you want to filter entries above/below a certain threshold, you can check this question. If you want to plot a heatmap of the correlation coefficients, you can check this answer and if you then run into the issue with overlapping axis-labels check the following post.

Storing and displaying unicode string (??????) using PHP and MySQL

For those who are looking for PHP ( >5.3.5 ) PDO statement, we can set charset as per below:

$dbh = new PDO('mysql:host=localhost;dbname=testdb;charset=utf8', 'username', 'password');

How to resolve Unable to load authentication plugin 'caching_sha2_password' issue

If you can update your connector to a version, which supports the new authentication plugin of MySQL 8, then do that. If that is not an option for some reason, change the default authentication method of your database user to native.

Random date in C#

I have taken @Joel Coehoorn answer and made the changes he adviced - put the variable out of the method and put all in class. Plus now the time is random too. Here is the result.

class RandomDateTime
    DateTime start;
    Random gen;
    int range;

    public RandomDateTime()
        start = new DateTime(1995, 1, 1);
        gen = new Random();
        range = (DateTime.Today - start).Days;

    public DateTime Next()
        return start.AddDays(gen.Next(range)).AddHours(gen.Next(0,24)).AddMinutes(gen.Next(0,60)).AddSeconds(gen.Next(0,60));

And example how to use to write 100 random DateTimes to console:

RandomDateTime date = new RandomDateTime();
for (int i = 0; i < 100; i++)

How to show Page Loading div until the page has finished loading?

for drupal in your theme custom_theme.theme file

function custom_theme_preprocess_html(&$variables) {
$variables['preloader'] = 1;

In html.html.twig file after skip main content link in body

{% if preloader %} 
  <div id="test-preloader" >
    <div id="preloader-inner" class="cssload-container">
      <div class="wait-text">{{ 'Please wait...'|t }} </div> 
      <div class="cssload-item cssload-moon"></div>
{% endif %}  

in css file

#test-preloader {
position: fixed;
background: white;
width: 100%;
height: 100%;
top: 0;
left: 0;
z-index: 9999;
.cssload-container .wait-text {
text-align: center;
padding-bottom: 15px;
color: #000;

.cssload-container .cssload-item {
 margin: auto;
 position: absolute;
 top: 0;
 right: 0;
 bottom: 0;
 left: 0;
 width: 131px;
 height: 131px;
 background-color: #fff;
 box-sizing: border-box;
 -o-box-sizing: border-box;
 -ms-box-sizing: border-box;
 -webkit-box-sizing: border-box;
 -moz-box-sizing: border-box;
 box-shadow: 0 0 21px 3px rgba(130, 130, 130, 0.26);
 -o-box-shadow: 0 0 21px 3px rgba(130, 130, 130, 0.26);
 -ms-box-shadow: 0 0 21px 3px rgba(130, 130, 130, 0.26);
 -webkit-box-shadow: 0 0 21px 3px rgba(130, 130, 130, 0.26);
 -moz-box-shadow: 0 0 21px 3px rgba(130, 130, 130, 0.26);

.cssload-container .cssload-moon {
border-bottom: 26px solid #008AFA;
border-radius: 50%;
-o-border-radius: 50%;
-ms-border-radius: 50%;
-webkit-border-radius: 50%;
-moz-border-radius: 50%;
animation: spin 1.45s ease infinite;
-o-animation: spin 1.45s ease infinite;
-ms-animation: spin 1.45s ease infinite;
-webkit-animation: spin 1.45s ease infinite;
-moz-animation: spin 1.45s ease infinite;

What is the difference between 'typedef' and 'using' in C++11?

I know the original poster has a great answer, but for anyone stumbling on this thread like I have there's an important note from the proposal that I think adds something of value to the discussion here, particularly to concerns in the comments about if the typedef keyword is going to be marked as deprecated in the future, or removed for being redundant/old:

It has been suggested to (re)use the keyword typedef ... to introduce template aliases:

template<class T>
  typedef std::vector<T, MyAllocator<T> > Vec;

That notation has the advantage of using a keyword already known to introduce a type alias. However, it also displays several disavantages [sic] among which the confusion of using a keyword known to introduce an alias for a type-name in a context where the alias does not designate a type, but a template; Vec is not an alias for a type, and should not be taken for a typedef-name. The name Vec is a name for the family std::vector<•, MyAllocator<•> > – where the bullet is a placeholder for a type-name.Consequently we do not propose the “typedef” syntax.On the other hand the sentence

template<class T>
  using Vec = std::vector<T, MyAllocator<T> >;

can be read/interpreted as: from now on, I’ll be using Vec<T> as a synonym for std::vector<T, MyAllocator<T> >. With that reading, the new syntax for aliasing seems reasonably logical.

To me, this implies continued support for the typedef keyword in C++ because it can still make code more readable and understandable.

Updating the using keyword was specifically for templates, and (as was pointed out in the accepted answer) when you are working with non-templates using and typedef are mechanically identical, so the choice is totally up to the programmer on the grounds of readability and communication of intent.

WCF, Service attribute value in the ServiceHost directive could not be found

If you have renamed anything verify the (Properties/) AssemblyInfo.cs is correct, as well as the header in the service file.


<%@ ServiceHost Language="C#" Debug="true" Service="Company.Namespace.WcfApp" CodeBehind="WcfApp.svc.cs" %>

Aligning with your namespace in your Service.svc.cs

phpmailer error "Could not instantiate mail function"

The PHPMailer help docs on this specific error helped to get me on the right path.

What we found is that php.ini did not have the sendmail_path defined, so I added that with sendmail_path = /usr/sbin/sendmail -t -i;

What is the garbage collector in Java?

The garbage collector allows your computer to simulate a computer with infinite memory. The rest is just mechanism.

It does this by detecting when chunks of memory are no longer accessible from your code, and returning those chunks to the free store.

EDIT: Yes, the link is for C#, but C# and Java are identical in this regard.

Could not calculate build plan: Plugin org.apache.maven.plugins:maven-jar-plugin:2.3.2 or one of its dependencies could not be resolved

I had this error, I follwed below three steps to solve,

1). check proxy settings in settings.xml refer,

2). .m2 diretory to release cached files causing problems

3) Point your eclipse to correct JDK installation. Refer No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK? to know how

How to move Jenkins from one PC to another

Following the Jenkins wiki, you'll have to:

  • Install a fresh Jenkins instance on the new server
  • Be sure the old and the new Jenkins instances are stopped
  • Archive all the content of the JENKINS_HOME of the old Jenkins instance
  • Extract the archive into the new JENKINS_HOME directory
  • Launch the new Jenkins instance
  • Do not forget to change documentation/links to your new instance of Jenkins :)
  • Do not forget to change the owner of the new Jenkins files : chown -R jenkins:jenkins $JENKINS_HOME

JENKINS_HOME is by default located in ~/.jenkins on a Linux installation, yet to exactly find where it is located, go on the http://your_jenkins_url/configure page and check the value of the first parameter: Home directory; this is the JENKINS_HOME.

Spring @Autowired and @Qualifier

The @Qualifier annotation is used to resolve the autowiring conflict, when there are multiple beans of same type.

The @Qualifier annotation can be used on any class annotated with @Component or on methods annotated with @Bean. This annotation can also be applied on constructor arguments or method parameters.


public interface Vehicle {
     public void start();
     public void stop();

There are two beans, Car and Bike implements Vehicle interface

public class Car implements Vehicle {

     public void start() {
           System.out.println("Car started");

     public void stop() {
           System.out.println("Car stopped");

public class Bike implements Vehicle {

     public void start() {
          System.out.println("Bike started");

     public void stop() {
          System.out.println("Bike stopped");

Injecting Bike bean in VehicleService using @Autowired with @Qualifier annotation. If you didn't use @Qualifier, it will throw NoUniqueBeanDefinitionException.

public class VehicleService {

    private Vehicle vehicle;

    public void service() {

Reference:- @Qualifier annotation example

How to automatically crop and center an image

Example with img tag but without background-image

This solution retains the img tag so that we do not lose the ability to drag or right-click to save the image but without background-image just center and crop with css.

Maintain the aspect ratio fine except in very hight images. (check the link)

(view in action)


<div class="center-cropped">
    <img src="" alt="" />

? CSS {
  width: 100px;
  height: 100px;
} img {
  height: 100%;
  min-width: 100%;
  left: 50%;
  position: relative;
  transform: translateX(-50%);

Java reverse an int value without using array

Reversing integer

  int n, reverse = 0;
  Scanner in = new Scanner(;
  n = in.nextInt();

  while(n != 0)
      reverse = reverse * 10;
      reverse = reverse + n%10;
      n = n/10;

  System.out.println("Reverse of the number is " + reverse);

Read large files in Java

Don't use read without arguments. It's very slow. Better read it to buffer and move it to file quickly.

Use bufferedInputStream because it supports binary reading.

And it's all.


boolean entered = false, last;
while (( entered |= last = ( condition ) )) {
        // Do while
} if ( !entered ) {
        // Else

You'r welcome.

How do I install cURL on Windows?

You can also use CygWin and install the cURL package. It works very well and flawlessly!!

Please initialize the log4j system properly warning

just configure your log4j property file path in beginning of main method: e.g.: PropertyConfigurator.configure("D:\files\");

iOS change navigation bar title font and color

Try this:

NSDictionary *textAttributes = [NSDictionary dictionaryWithObjectsAndKeys:
                                [UIColor whiteColor],NSForegroundColorAttributeName,
                                [UIColor whiteColor],NSBackgroundColorAttributeName,nil];
self.navigationController.navigationBar.titleTextAttributes = textAttributes;

WPF Label Foreground Color

I checked your XAML, it works fine - e.g. both labels have a gray foreground.
My guess is that you have some style which is affecting the way it looks...

Try moving your XAML to a brand-new window and see for yourself... Then, check if you have any themes or styles (in the Window.Resources for instance) which might be affecting the labels...

Cast received object to a List<object> or IEnumerable<object>

C# 4 will have covariant and contravariant template parameters, but until then you have to do something nongeneric like

IList collection = (IList)myObject;

ORA-00942: table or view does not exist (works when a separate sql, but does not work inside a oracle function)

There's a strong chance that the privileges to select from table1 have been granted to a role, and the role has been granted to you. Privileges granted to a role are not available to PL/SQL written by a user, even if the user has been granted the role.

You see this a lot for users that have been granted the dba role on objects owned by sys. A user with dba role will be able to, say, SELECT * from V$SESSION, but will not be able to write a function that includes SELECT * FROM V$SESSION.

The fix is to grant explicit permissions on the object in question to the user directly, for example, in the case above, the SYS user has to GRANT SELECT ON V_$SESSION TO MyUser;

How can I add a Google search box to my website?

This is one of the way to add google site search to websites:

<form action="" class="searchform" method="get" name="searchform" target="_blank">_x000D_
<input name="sitesearch" type="hidden" value="">_x000D_
<input autocomplete="on" class="form-control search" name="q" placeholder="Search in" required="required"  type="text">_x000D_
<button class="button" type="submit">Search</button>_x000D_

/lib/ bad ELF interpreter: No such file or directory

I had the same issue, the following commands can resolve:

sudo yum install  glibc-common glibc  (mutual dependency)
sudo yum install  glibc.i686  (the missing version)

How to force input to only allow Alpha Letters?

If your form is PHP based, it would work this way within your " <?php $data = array(" code:

    'onkeypress' => 'return /[a-z 0-9]/i.test(event.key)', 

How to check if a python module exists without importing it


To check if import can find something in python2, using imp

import imp
    found = True
except ImportError:
    found = False

To find dotted imports, you need to do more:

import imp
    spam_info = imp.find_module('spam')
    spam = imp.load_module('spam', *spam_info)
    imp.find_module('eggs', spam.__path__) # __path__ is already a list
    found = True
except ImportError:
    found = False

You can also use pkgutil.find_loader (more or less the same as the python3 part

import pkgutil
eggs_loader = pkgutil.find_loader('eggs')
found = eggs_loader is not None


Python3 = 3.3

You should use importlib, How I went about doing this was:

import importlib
spam_loader = importlib.find_loader('spam')
found = spam_loader is not None

My expectation being, if you can find a loader for it, then it exists. You can also be a bit more smart about it, like filtering out what loaders you will accept. For example:

import importlib
spam_loader = importlib.find_loader('spam')
# only accept it as valid if there is a source file for the module - no bytecode only.
found = issubclass(type(spam_loader), importlib.machinery.SourceFileLoader)

Python3 = 3.4

In Python3.4 importlib.find_loader python docs was deprecated in favour of importlib.util.find_spec. The recommended method is the importlib.util.find_spec. There are others like importlib.machinery.FileFinder, which is useful if you're after a specific file to load. Figuring out how to use them is beyond the scope of this.

import importlib
spam_spec = importlib.util.find_spec("spam")
found = spam_spec is not None

This also works with relative imports but you must supply the starting package, so you could also do:

import importlib
spam_spec = importlib.util.find_spec("..spam", package="")
found = spam_spec is not None == "eggs.spam"

While I'm sure there exists a reason for doing this - I'm not sure what it would be.


When trying to find a submodule, it will import the parent module (for all of the above methods)!


print("module food loaded")

print("module eggs")

were you then to run
>>> import importlib
>>> spam_spec = importlib.find_spec("food.eggs")
module food loaded
ModuleSpec(name='food.eggs', loader=<_frozen_importlib.SourceFileLoader object at 0x10221df28>, origin='/home/user/food/')

comments welcome on getting around this


  • @rvighne for importlib
  • @lucas-guido for python3.3+ depricating find_loader
  • @enpenax for pkgutils.find_loader behaviour in python2.7

How to store decimal values in SQL Server?

DECIMAL(18,0) will allow 0 digits after the decimal point.

Use something like DECIMAL(18,4) instead that should do just fine!

That gives you a total of 18 digits, 4 of which after the decimal point (and 14 before the decimal point).

How to detect duplicate values in PHP array?

You could try turning that array into a associative array with the fruits as keys and the number of occurrences as values. Bit long-winded, but it looks like:

$array = array('apple', 'orange', 'pear', 'banana', 'apple',
   'pear', 'kiwi', 'kiwi', 'kiwi');
$new_array = array();
foreach ($array as $key => $value) {
        $new_array[$value] += 1;
        $new_array[$value] = 1;
foreach ($new_array as $fruit => $n) {
    echo $fruit;
    if($n > 1)
        echo "($n)";
    echo "<br />";

Regexp Java for password validation

For anyone interested in minimum requirements for each type of character, I would suggest making the following extension over Tomalak's accepted answer:


Notice that this is a formatting string and not the final regex pattern. Just substitute %d with the minimum required occurrences for: digits, lowercase, uppercase, non-digit/character, and entire password (respectively). Maximum occurrences are unlikely (unless you want a max of 0, effectively rejecting any such characters) but those could be easily added as well. Notice the extra grouping around each type so that the min/max constraints allow for non-consecutive matches. This worked wonders for a system where we could centrally configure how many of each type of character we required and then have the website as well as two different mobile platforms fetch that information in order to construct the regex pattern based on the above formatting string.

grep without showing path/file:line

From the man page:

-h, --no-filename
    Suppress the prefixing of file names on output. This is the default when there
    is only one file (or only standard input) to search.

Why is json_encode adding backslashes?

Just use the "JSON_UNESCAPED_SLASHES" Option (added after version 5.4).


Relay access denied on sending mail, Other domain outside of network

I'm using THUNDERBIRD as MUA and I have same issues. I solved adding the IP address of my home PC on mynetworks parameter on

mynetworks = [::ffff:]/104 [::1]/128 MyIpAddress

P.S. I don't have a static ip for my home PC so when my ISP change it I ave to adjust every time.

Checking if a SQL Server login already exists

This is for Azure SQL:

IF (EXISTS(SELECT TOP 1 1 FROM sys.sql_logins WHERE [name] = '<login>'))
    DROP LOGIN [<login>];

Source: How to check whether database user already exists in Azure SQL Database

Angular2 handling http response

Update alpha 47

As of alpha 47 the below answer (for alpha46 and below) is not longer required. Now the Http module handles automatically the errores returned. So now is as easy as follows

  .get('Some Url')
  .map(res => res.json())
    (data) => = data,
    (err) => this.error = err); // Reach here if fails

Alpha 46 and below

You can handle the response in the map(...), before the subscribe.

  .get('Some Url')
  .map(res => {
    // If request fails, throw an Error that will be caught
    if(res.status < 200 || res.status >= 300) {
      throw new Error('This request has failed ' + res.status);
    // If everything went fine, return the response
    else {
      return res.json();
    (data) => = data, // Reach here if res.status >= 200 && <= 299
    (err) => this.error = err); // Reach here if fails

Here's a plnkr with a simple example.

Note that in the next release this won't be necessary because all status codes below 200 and above 299 will throw an error automatically, so you won't have to check them by yourself. Check this commit for more info.

What's the difference between UTF-8 and UTF-8 without BOM?

Quoted at the bottom of the Wikipedia page on BOM:

"Use of a BOM is neither required nor recommended for UTF-8, but may be encountered in contexts where UTF-8 data is converted from other encoding forms that use a BOM or where the BOM is used as a UTF-8 signature"

Maven is not working in Java 8 when Javadoc tags are incomplete

I don't think just turning off DocLint is a good solution, at least not long term. It is good that Javadoc has become a bit more strict so the right way to fix the build problem is to fix the underlying problem. Yes, you'll ultimately need to fix those source code files.

Here are the things to look out for that you could previously get away with:

  • Malformed HTML (for example a missing end-tag, un-escaped brackets, etc)
  • Invalid {@link }s. (same goes for similar tags such as @see)
  • Invalid @author values. This used to be accepted : @author John <[email protected]> but not so anymore because of the un-escaped brackets.
  • HTML tables in Javadoc now require a summary or caption. See this question for explanation.

You'll simply have to fix your source code files and keep building your Javadoc until it can build without a failure. Cumbersome yes, but personally I like when I have brought my projects up to DocLint level because it means I can be more confident that the Javadoc I produce is actually what I intend.

There's of course the problem if you are generating Javadoc on some source code you've not produced yourself, for example because it comes from some code generator, e.g. wsimport. Strange that Oracle didn't prepare their own tools for JDK8 compliance before actually releasing JDK8. It seems it won't be fixed until Java 9. Only in this particular case I suggest to turn off DocLint as documented elsewhere on this page.

How do I see all foreign keys to a table or column?

For a Table:


For a Column:


Basically, we changed REFERENCED_TABLE_NAME with REFERENCED_COLUMN_NAME in the where clause.

Can't drop table: A foreign key constraint fails

But fortunately, with the MySQL FOREIGN_KEY_CHECKS variable, you don't have to worry about the order of your DROP TABLE statements at all, and you can write them in any order you like -- even the exact opposite -- like this:

drop table if exists customers;
drop table if exists orders;
drop table if exists order_details;

For more clarification, check out the link below:

How to send characters in PuTTY serial communication only when pressing enter?

The settings you need are "Local echo" and "Line editing" under the "Terminal" category on the left.

To get the characters to display on the screen as you enter them, set "Local echo" to "Force on".

To get the terminal to not send the command until you press Enter, set "Local line editing" to "Force on".

PuTTY Line discipline options


From the PuTTY User Manual (Found by clicking on the "Help" button in PuTTY):

4.3.8 ‘Local echo’

With local echo disabled, characters you type into the PuTTY window are not echoed in the window by PuTTY. They are simply sent to the server. (The server might choose to echo them back to you; this can't be controlled from the PuTTY control panel.)

Some types of session need local echo, and many do not. In its default mode, PuTTY will automatically attempt to deduce whether or not local echo is appropriate for the session you are working in. If you find it has made the wrong decision, you can use this configuration option to override its choice: you can force local echo to be turned on, or force it to be turned off, instead of relying on the automatic detection.

4.3.9 ‘Local line editing’ Normally, every character you type into the PuTTY window is sent immediately to the server the moment you type it.

If you enable local line editing, this changes. PuTTY will let you edit a whole line at a time locally, and the line will only be sent to the server when you press Return. If you make a mistake, you can use the Backspace key to correct it before you press Return, and the server will never see the mistake.

Since it is hard to edit a line locally without being able to see it, local line editing is mostly used in conjunction with local echo (section 4.3.8). This makes it ideal for use in raw mode or when connecting to MUDs or talkers. (Although some more advanced MUDs do occasionally turn local line editing on and turn local echo off, in order to accept a password from the user.)

Some types of session need local line editing, and many do not. In its default mode, PuTTY will automatically attempt to deduce whether or not local line editing is appropriate for the session you are working in. If you find it has made the wrong decision, you can use this configuration option to override its choice: you can force local line editing to be turned on, or force it to be turned off, instead of relying on the automatic detection.

Putty sometimes makes wrong choices when "Auto" is enabled for these options because it tries to detect the connection configuration. Applied to serial line, this is a bit trickier to do.

Finding last index of a string in Oracle

Use -1 as the start position:

INSTR('JD-EQ-0001', '-', -1)

How do I determine the dependencies of a .NET application?

To browse .NET code dependencies, you can use the capabilities of the tool NDepend. The tool proposes:

For example such query can look like:

from m in Methods 
let depth = m.DepthOfIsUsing("NHibernate.NHibernateUtil.Entity(Type)") 
where depth  >= 0 && m.IsUsing("System.IDisposable")
orderby depth
select new { m, depth }

And its result looks like: (notice the code metric depth, 1 is for direct callers, 2 for callers of direct callers...) (notice also the Export to Graph button to export the query result to a Call Graph)

NDepend dependencies browsing through C# LINQ query

The dependency graph looks like:

NDepend Dependency Graph

The dependency matrix looks like:

NDepend Dependency Matrix

The dependency matrix is de-facto less intuitive than the graph, but it is more suited to browse complex sections of code like:

NDepend Matrix vs Graph

Disclaimer: I work for NDepend

Pagination response payload from a RESTful API

As someone who has written several libraries for consuming REST services, let me give you the client perspective on why I think wrapping the result in metadata is the way to go:

  • Without the total count, how can the client know that it has not yet received everything there is and should continue paging through the result set? In a UI that didn't perform look ahead to the next page, in the worst case this might be represented as a Next/More link that didn't actually fetch any more data.
  • Including metadata in the response allows the client to track less state. Now I don't have to match up my REST request with the response, as the response contains the metadata necessary to reconstruct the request state (in this case the cursor into the dataset).
  • If the state is part of the response, I can perform multiple requests into the same dataset simultaneously, and I can handle the requests in any order they happen to arrive in which is not necessarily the order I made the requests in.

And a suggestion: Like the Twitter API, you should replace the page_number with a straight index/cursor. The reason is, the API allows the client to set the page size per-request. Is the returned page_number the number of pages the client has requested so far, or the number of the page given the last used page_size (almost certainly the later, but why not avoid such ambiguity altogether)?

Using unset vs. setting a variable to empty

So, by unset'ting the array index 2, you essentially remove that element in the array and decrement the array size (?).

I made my own test..

foo=(5 6 8)
echo ${#foo[*]}
unset foo
echo ${#foo[*]}

Which results in..


So just to clarify that unset'ting the entire array will in fact remove it entirely.

Table with table-layout: fixed; and how to make one column wider

Are you creating a very large table (hundreds of rows and columns)? If so, table-layout: fixed; is a good idea, as the browser only needs to read the first row in order to compute and render the entire table, so it loads faster.

But if not, I would suggest dumping table-layout: fixed; and changing your css as follows:

table th, table td{
border: 1px solid #000;
width:20px;  //or something similar   

table td.wideRow, table th.wideRow{
width: 300px;

PHP parse/syntax errors; and how to solve them

Unexpected T_IS_EQUAL
Unexpected T_IS_NOT_EQUAL
Unexpected <
Unexpected >

Comparison operators such as ==, >=, ===, !=, <>, !== and <= or < and > mostly should be used just in expressions, such as if expressions. If the parser complains about them, then it often means incorrect paring or mismatched ( ) parens around them.

  1. Parens grouping

    In particular for if statements with multiple comparisons you must take care to correctly count opening and closing parenthesis:

    if (($foo < 7) && $bar) > 5 || $baz < 9) { ... }

    Here the if condition here was already terminated by the )

    Once your comparisons become sufficiently complex it often helps to split it up into multiple and nested if constructs rather.

  2. isset() mashed with comparing

    A common newcomer is pitfal is trying to combine isset() or empty() with comparisons:

    if (empty($_POST["var"] == 1)) {

    Or even:

    if (isset($variable !== "value")) {

    This doesn't make sense to PHP, because isset and empty are language constructs that only accept variable names. It doesn't make sense to compare the result either, because the output is only/already a boolean.

  3. Confusing >= greater-or-equal with => array operator

    Both operators look somewhat similar, so they sometimes get mixed up:

    if ($var => 5) { ... }

    You only need to remember that this comparison operator is called "greater than or equal" to get it right.

    See also: If statement structure in PHP

  4. Nothing to compare against

    You also can't combine two comparisons if they pertain the same variable name:

    if ($xyz > 5 and < 100)

    PHP can't deduce that you meant to compare the initial variable again. Expressions are usually paired according to operator precedence, so by the time the < is seen, there'd be only a boolean result left from the original variable.

    See also: unexpected T_IS_SMALLER_OR_EQUAL

  5. Comparison chains

    You can't compare against a variable with a row of operators:

     $reult = (5 < $x < 10);

    This has to be broken up into two comparisons, each against $x.

    This is actually more a case of blacklisted expressions (due to equivalent operator associativity). It's syntactically valid in a few C-style languages, but PHP wouldn't interpret it as expected comparison chain either.

  6. Unexpected >
    Unexpected <

    The greater than > or less than < operators don't have a custom T_XXX tokenizer name. And while they can be misplaced like all they others, you more often see the parser complain about them for misquoted strings and mashed HTML:

    print "<a href='z">Hello</a>";

    This amounts to a string "<a href='z" being compared > to a literal constant Hello and then another < comparison. Or that's at least how PHP sees it. The actual cause and syntax mistake was the premature string " termination.

    It's also not possible to nest PHP start tags:

    <?php echo <?php my_func(); ?>

See also:

Timestamp to human readable format

Hours, minutes and seconds depend on the time zone of your operating system. In GMT (UST) it's 22:00:00 but in different timezones it can be anything. So add the timezone offset to the time to create the GMT date:

var d = new Date();
date = new Date(timestamp*1000 + d.getTimezoneOffset() * 60000)

How to use Session attributes in Spring-mvc

Isn't it easiest and shortest that way? I knew it and just tested it - working perfect here:

public String hello(HttpSession session) {
    return "hello";

p.s. I came here searching for an answer of "How to use Session attributes in Spring-mvc", but read so many without seeing the most obvious that I had written in my code. I didn't see it, so I thought its wrong, but no it was not. So lets share that knowledge with the easiest solution for the main question.

iOS Remote Debugging

I am using remotedebug-ios-webkit-adapter, works well for me with IOS and debugger open in Chrome on Windows 10.

Will be glad if it helps some one Link

Programmatically get the version number of a DLL

Kris, your version works great when needing to load the assembly from the actual DLL file (and if the DLL is there!), however, one will get a much unwanted error if the DLL is EMBEDDED (i.e., not a file but an embedded DLL).

The other thing is, if one uses a versioning scheme with something like "1.2012.0508.0101", when one gets the version string you'll actually get "1.2012.518.101"; note the missing zeros.

So, here's a few extra functions to get the version of a DLL (embedded or from the DLL file):

    public static System.Reflection.Assembly GetAssembly(string pAssemblyName)
        System.Reflection.Assembly tMyAssembly = null;

        if (string.IsNullOrEmpty(pAssemblyName)) { return tMyAssembly; }
        tMyAssembly = GetAssemblyEmbedded(pAssemblyName);
        if (tMyAssembly == null) { GetAssemblyDLL(pAssemblyName); }

        return tMyAssembly;
    }//System.Reflection.Assembly GetAssemblyEmbedded(string pAssemblyDisplayName)

    public static System.Reflection.Assembly GetAssemblyEmbedded(string pAssemblyDisplayName)
        System.Reflection.Assembly tMyAssembly = null;

        if(string.IsNullOrEmpty(pAssemblyDisplayName)) { return tMyAssembly; }
        try //try #a
            tMyAssembly = System.Reflection.Assembly.Load(pAssemblyDisplayName);
        }// try #a
        catch (Exception ex)
            string m = ex.Message;
        }// try #a
        return tMyAssembly;
    }//System.Reflection.Assembly GetAssemblyEmbedded(string pAssemblyDisplayName)

    public static System.Reflection.Assembly GetAssemblyDLL(string pAssemblyNameDLL)
        System.Reflection.Assembly tMyAssembly = null;

        if (string.IsNullOrEmpty(pAssemblyNameDLL)) { return tMyAssembly; }
        try //try #a
            if (!pAssemblyNameDLL.ToLower().EndsWith(".dll")) { pAssemblyNameDLL += ".dll"; }
            tMyAssembly = System.Reflection.Assembly.LoadFrom(pAssemblyNameDLL);
        }// try #a
        catch (Exception ex)
            string m = ex.Message;
        }// try #a
        return tMyAssembly;
    }//System.Reflection.Assembly GetAssemblyFile(string pAssemblyNameDLL)

    public static string GetVersionStringFromAssembly(string pAssemblyDisplayName)
        string tVersion = "Unknown";
        System.Reflection.Assembly tMyAssembly = null;

        tMyAssembly = GetAssembly(pAssemblyDisplayName);
        if (tMyAssembly == null) { return tVersion; }
        tVersion = GetVersionString(tMyAssembly.GetName().Version.ToString());
        return tVersion;
    }//string GetVersionStringFromAssemblyEmbedded(string pAssemblyDisplayName)

    public static string GetVersionString(Version pVersion)
        string tVersion = "Unknown";
        if (pVersion == null) { return tVersion; }
        tVersion = GetVersionString(pVersion.ToString());
        return tVersion;
    }//string GetVersionString(Version pVersion)

    public static string GetVersionString(string pVersionString)
        string tVersion = "Unknown";
        string[] aVersion;

        if (string.IsNullOrEmpty(pVersionString)) { return tVersion; }
        aVersion = pVersionString.Split('.');
        if (aVersion.Length > 0) { tVersion = aVersion[0]; }
        if (aVersion.Length > 1) { tVersion += "." + aVersion[1]; }
        if (aVersion.Length > 2) { tVersion += "." + aVersion[2].PadLeft(4, '0'); }
        if (aVersion.Length > 3) { tVersion += "." + aVersion[3].PadLeft(4, '0'); }

        return tVersion;
    }//string GetVersionString(Version pVersion)

    public static string GetVersionStringFromAssemblyEmbedded(string pAssemblyDisplayName)
        string tVersion = "Unknown";
        System.Reflection.Assembly tMyAssembly = null;

        tMyAssembly = GetAssemblyEmbedded(pAssemblyDisplayName);
        if (tMyAssembly == null) { return tVersion; }
        tVersion = GetVersionString(tMyAssembly.GetName().Version.ToString());
        return tVersion;
    }//string GetVersionStringFromAssemblyEmbedded(string pAssemblyDisplayName)

    public static string GetVersionStringFromAssemblyDLL(string pAssemblyDisplayName)
        string tVersion = "Unknown";
        System.Reflection.Assembly tMyAssembly = null;

        tMyAssembly = GetAssemblyDLL(pAssemblyDisplayName);
        if (tMyAssembly == null) { return tVersion; }
        tVersion = GetVersionString(tMyAssembly.GetName().Version.ToString());
        return tVersion;
    }//string GetVersionStringFromAssemblyEmbedded(string pAssemblyDisplayName)

OOP vs Functional Programming vs Procedural

One of my friends is writing a graphics app using NVIDIA CUDA. Application fits in very nicely with OOP paradigm and the problem can be decomposed into modules neatly. However, to use CUDA you need to use C, which doesn't support inheritance. Therefore, you need to be clever.

a) You devise a clever system which will emulate inheritance to a certain extent. It can be done!

i) You can use a hook system, which expects every child C of parent P to have a certain override for function F. You can make children register their overrides, which will be stored and called when required.

ii) You can use struct memory alignment feature to cast children into parents.

This can be neat but it's not easy to come up with future-proof, reliable solution. You will spend lots of time designing the system and there is no guarantee that you won't run into problems half-way through the project. Implementing multiple inheritance is even harder, if not almost impossible.

b) You can use consistent naming policy and use divide and conquer approach to create a program. It won't have any inheritance but because your functions are small, easy-to-understand and consistently formatted you don't need it. The amount of code you need to write goes up, it's very hard to stay focused and not succumb to easy solutions (hacks). However, this ninja way of coding is the C way of coding. Staying in balance between low-level freedom and writing good code. Good way to achieve this is to write prototypes using a functional language. For example, Haskell is extremely good for prototyping algorithms.

I tend towards approach b. I wrote a possible solution using approach a, and I will be honest, it felt very unnatural using that code.

Does the join order matter in SQL?

For INNER joins, no, the order doesn't matter. The queries will return same results, as long as you change your selects from SELECT * to SELECT a.*, b.*, c.*.

For (LEFT, RIGHT or FULL) OUTER joins, yes, the order matters - and (updated) things are much more complicated.

First, outer joins are not commutative, so a LEFT JOIN b is not the same as b LEFT JOIN a

Outer joins are not associative either, so in your examples which involve both (commutativity and associativity) properties:

    ON b.ab_id = a.ab_id
    ON c.ac_id = a.ac_id

is equivalent to:

    ON c.ac_id = a.ac_id
    ON b.ab_id = a.ab_id


    ON  b.ab_id = a.ab_id
    ON  c.ac_id = a.ac_id
    AND c.bc_id = b.bc_id

is not equivalent to:

    ON  c.ac_id = a.ac_id
    ON  b.ab_id = a.ab_id
    AND b.bc_id = c.bc_id

Another (hopefully simpler) associativity example. Think of this as (a LEFT JOIN b) LEFT JOIN c:

    ON b.ab_id = a.ab_id          -- AB condition
    ON c.bc_id = b.bc_id          -- BC condition

This is equivalent to a LEFT JOIN (b LEFT JOIN c):

    b LEFT JOIN c
        ON c.bc_id = b.bc_id          -- BC condition
    ON b.ab_id = a.ab_id          -- AB condition

only because we have "nice" ON conditions. Both ON b.ab_id = a.ab_id and c.bc_id = b.bc_id are equality checks and do not involve NULL comparisons.

You can even have conditions with other operators or more complex ones like: ON a.x <= b.x or ON a.x = 7 or ON a.x LIKE b.x or ON (a.x, a.y) = (b.x, b.y) and the two queries would still be equivalent.

If however, any of these involved IS NULL or a function that is related to nulls like COALESCE(), for example if the condition was b.ab_id IS NULL, then the two queries would not be equivalent.

Calculating a directory's size using Python?

Some of the approaches suggested so far implement a recursion, others employ a shell or will not produce neatly formatted results. When your code is one-off for Linux platforms, you can get formatting as usual, recursion included, as a one-liner. Except for the print in the last line, it will work for current versions of python2 and python3:
import subprocess

def du(path):
    """disk usage in human readable format (e.g. '2,1GB')"""
    return subprocess.check_output(['du','-sh', path]).split()[0].decode('utf-8')

if __name__ == "__main__":

is simple, efficient and will work for files and multilevel directories:

$ chmod 750
$ ./

How to pass in password to pg_dump?

$ PGPASSWORD="mypass" pg_dump -i -h localhost -p 5432 -U username -F c -b -v -f dumpfilename.dump databasename

Can I stop 100% Width Text Boxes from extending beyond their containers?

If you can't use box-sizing:border-box you could try removing the width:100% and putting a very large size attribute in the <input> element, drawback is however you have to modify the html, and can't do it with CSS only:

<input size="1000"></input>

Toggle input disabled attribute using jQuery

Quite a while later, and thanks to @arne, I created this similar small function to handle where the input should be disabled AND hidden, or enabled AND shown:

function toggleInputState(el, on) {
  // 'on' = true(visible) or false(hidden)
  // If a field is to be shown, enable it; if hidden, disable it.
  // Disabling will prevent the field's value from being submitted
  $(el).prop('disabled', !on).toggle(on);

Then a jQuery object (such as $('input[name="something"]') ) is simply switched using:

toggleInputState(myElement, myBoolean)

How do I install PHP cURL on Linux Debian?

I wrote an article on topis how to [manually install curl on debian linu][1]x.

[1]: This is its shortcut:

  1. cd /usr/local/src
  2. wget
  3. tar -xvzf curl-7.36.0.tar.gz
  4. rm *.gz
  5. cd curl-7.6.0
  6. ./configure
  7. make
  8. make install

And restart Apache. If you will have an error during point 6, try to run apt-get install build-essential.

Does JavaScript guarantee object property order?

The iteration order for objects follows a certain set of rules since ES2015, but it does not (always) follow the insertion order. Simply put, the iteration order is a combination of the insertion order for strings keys, and ascending order for number-like keys:

// key order: 1, foo, bar
const obj = { "foo": "foo", "1": "1", "bar": "bar" }

Using an array or a Map object can be a better way to achieve this. Map shares some similarities with Object and guarantees the keys to be iterated in order of insertion, without exception:

The keys in Map are ordered while keys added to object are not. Thus, when iterating over it, a Map object returns keys in order of insertion. (Note that in the ECMAScript 2015 spec objects do preserve creation order for string and Symbol keys, so traversal of an object with ie only string keys would yield keys in order of insertion)

As a note, properties order in objects weren’t guaranteed at all before ES2015. Definition of an Object from ECMAScript Third Edition (pdf):

4.3.3 Object

An object is a member of the type Object. It is an unordered collection of properties each of which contains a primitive value, object, or function. A function stored in a property of an object is called a method.

Could not load file or assembly 'System.Web.WebPages.Razor, Version=

I downgraded via NuGet to MVC 4 and then upgraded again to 5.2.7 and it fixed this issue

Sass and combined child selector

Without the combined child selector you would probably do something similar to this:

foo {
  bar {
    baz {
      color: red;

If you want to reproduce the same syntax with >, you could to this:

foo {
  > bar {
    > baz {
      color: red;

This compiles to this:

foo > bar > baz {
  color: red;

Or in sass:

  > bar
    > baz
      color: red

Error in : figure margins too large, Scatter plot

Invoking to make RStudio open up a new graphics device with default settings worked for me. HTH.

Calculate the date yesterday in JavaScript

Give this a try, works for me:

var today = new Date();
var yesterday = new Date(today.setDate(today.getDate() - 1)); `

This got me a date object back for yesterday

Static image src in Vue.js template

declare new variable that the value contain the path of image

const imgLink = require('../../assets/your-image.png')

then call the variable

export default {
    name: 'onepage',
            img: imgLink,

bind that on html, this the example:

<a href="#"><img v-bind:src="img" alt="" class="logo"></a>

hope it will help

How to display a Yes/No dialog box on Android?

you can implement a generic solution for decisions and use in another case not just for yes/no and custom the alert with animations or layout:

Something like this; first create your class for transfer datas:

public class AlertDecision {

    private String question = "";
    private String strNegative = "";
    private String strPositive = "";

    public AlertDecision question(@NonNull String question) {
        this.question = question;
        return this;

    public AlertDecision ansPositive(@NonNull String strPositive) {
        this.strPositive = strPositive;
        return this;

    public AlertDecision ansNegative(@NonNull String strNegative) {
        this.strNegative = strNegative;
        return this;

    public String getQuestion() {
        return question;

    public String getAnswerNegative() {
        return strNegative;

    public String getAnswerPositive() {
        return strPositive;

after a interface for return the result

public interface OnAlertDecisionClickListener {

     * Interface definition for a callback to be invoked when a view is clicked.
     * @param dialog the dialog that was clicked
     * @param object The object in the position of the view
    void onPositiveDecisionClick(DialogInterface dialog, Object object);
    void onNegativeDecisionClick(DialogInterface dialog, Object object);

Now you can create an utils for access easily (in this class you can implement different animation or custom layout for the alert):

public class AlertViewUtils {

    public static void showAlertDecision(Context context,
                                         @NonNull AlertDecision decision,
                                         final OnAlertDecisionClickListener listener,
                                         final Object object) {

        AlertDialog.Builder builder = new AlertDialog.Builder(context);
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        listener.onPositiveDecisionClick(dialog, object);

                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        listener.onNegativeDecisionClick(dialog, object);
                }); dialog = builder.create();;

and the last call in activity or fragment; you can use this in you case or for other task:

public class MainActivity extends AppCompatActivity {

    protected void onCreate(Bundle savedInstanceState) {

    public void initResources() {
        Button doSomething = (Button) findViewById(;

    private View.OnClickListener getDecisionListener() {
        return new View.OnClickListener() {
            public void onClick(View v) {
                AlertDecision decision = new AlertDecision()
                        .question("question ...")
                        .ansNegative("negative action...")
                        .ansPositive("positive action... ");
                        decision, getOnDecisionListener(), v);

    private OnAlertDecisionClickListener getOnDecisionListener() {
        return new OnAlertDecisionClickListener() {
            public void onPositiveDecisionClick(DialogInterface dialog, Object object) {

                //do something like create, show views, etc...

            public void onNegativeDecisionClick(DialogInterface dialog, Object object) {
                //do something like delete, close session, etc ...

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

Just use;


col align right

For The Bootstrap 4+

This Code Worked Well for me

<div class="row">
        <div class="col">
            <div class="ml-auto">
                this content will be in the Right
        <div class="col mr-auto">
            <div class="mr-auto">
                this content will be in the leftt

How to upload multiple files using PHP, jQuery and AJAX

Using this source code you can upload multiple file like google one by one through ajax. Also you can see the uploading progress


 <input type="file" id="multiupload" name="uploadFiledd[]" multiple >
 <button type="button" id="upcvr" class="btn btn-primary">Start Upload</button>
 <div id="uploadsts"></div>



    function uploadajax(ttl,cl){

    var fileList = $('#multiupload').prop("files");

    var form_data =  "";

    form_data = new FormData();
    form_data.append("upload_image", fileList[cl]);

    var request = $.ajax({
              url: "upload.php",
              cache: false,
              contentType: false,
              processData: false,
              async: true,
              data: form_data,
              type: 'POST', 
              xhr: function() {  
                  var xhr = $.ajaxSettings.xhr();
                  xhr.upload.addEventListener('progress', function(event){
                      var percent = 0;
                      if (event.lengthComputable) {
                          percent = Math.ceil(event.loaded / * 100);
                   }, false);
                 return xhr;
              success: function (res, status) {
                  if (status == 'success') {
                      percent = 0;
                      $('#prog' + cl).text('');
                      $('#prog' + cl).text('--Success: ');
                      if (cl < ttl) {
                          uploadajax(ttl, cl + 1);
                      } else {
              fail: function (res) {

        var fileList = $('#multiupload').prop("files");
        var i;
        for ( i = 0; i < fileList.length; i++) {
            $('#uploadsts').append('<p class="upload-page">'+fileList[i].name+'<span class="loading-prep" id="prog'+i+'"></span></p>');
            if(i == fileList.length-1){



Do I need <class> elements in persistence.xml?

Hibernate doesn't support <exclude-unlisted-classes>false</exclude-unlisted-classes> under SE, (another poster mentioned this works with TopLink and EclipseLink).

There are tools that will auto-generate the list of classes to persistence.xml e.g. the Import Database Schema wizard in IntelliJ. Once you've got your project's initial classes in persistence.xml it should be simple to add/remove single classes by hand as your project progresses.

Show row number in row header of a DataGridView

It seems that it doesn't turn it into a string. Try

row.HeaderCell.Value = String.Format("{0}", row.Index + 1);

Building executable jar with maven?

Right click the project and give maven build,maven clean,maven generate resource and maven install.The jar file will automatically generate.

Jackson with JSON: Unrecognized field, not marked as ignorable

Your input


indicates that it is an Object, with a field named "wrapper", which is a Collection of Students. So my recommendation would be,

Wrapper = mapper.readValue(jsonStr , Wrapper.class);

where Wrapper is defined as

class Wrapper {
    List<Student> wrapper;

Check if something is (not) in a list in Python

The bug is probably somewhere else in your code, because it should work fine:

>>> 3 not in [2, 3, 4]
>>> 3 not in [4, 5, 6]

Or with tuples:

>>> (2, 3) not in [(2, 3), (5, 6), (9, 1)]
>>> (2, 3) not in [(2, 7), (7, 3), "hi"]

Find the index of a dict within a list, by matching the dict's value

Seems most logical to use a filter/index combo:

names=[{}, {'name': 'Tom'},{'name': 'Tony'}]
names.index(filter(lambda n: n.get('name') == 'Tom', names)[0])

And if you think there could be multiple matches:

[names.index(n) for item in filter(lambda n: n.get('name') == 'Tom', names)]

Converting an int into a 4 byte char array (C)

In your question, you stated that you want to convert a user input of 175 to 00000000 00000000 00000000 10101111, which is big endian byte ordering, also known as network byte order.

A mostly portable way to convert your unsigned integer to a big endian unsigned char array, as you suggested from that "175" example you gave, would be to use C's htonl() function (defined in the header <arpa/inet.h> on Linux systems) to convert your unsigned int to big endian byte order, then use memcpy() (defined in the header <string.h> for C, <cstring> for C++) to copy the bytes into your char (or unsigned char) array.

The htonl() function takes in an unsigned 32-bit integer as an argument (in contrast to htons(), which takes in an unsigned 16-bit integer) and converts it to network byte order from the host byte order (hence the acronym, Host TO Network Long, versus Host TO Network Short for htons), returning the result as an unsigned 32-bit integer. The purpose of this family of functions is to ensure that all network communications occur in big endian byte order, so that all machines can communicate with each other over a socket without byte order issues. (As an aside, for big-endian machines, the htonl(), htons(), ntohl() and ntohs() functions are generally compiled to just be a 'no op', because the bytes do not need to be flipped around before they are sent over or received from a socket since they're already in the proper byte order)

Here's the code:

#include <stdio.h>
#include <arpa/inet.h>
#include <string.h>

int main() {
    unsigned int number = 175;

    unsigned int number2 = htonl(number);
    char numberStr[4];
    memcpy(numberStr, &number2, 4);

    printf("%x %x %x %x\n", numberStr[0], numberStr[1], numberStr[2], numberStr[3]);

    return 0;

Note that, as caf said, you have to print the characters as unsigned characters using printf's %x format specifier.

The above code prints 0 0 0 af on my machine (an x86_64 machine, which uses little endian byte ordering), which is hex for 175.

Difference in months between two dates

Simple and fast solution to count total months between 2 dates. If you want to get only different months, not counting the one that is in From date - just remove +1 from code.

public static int GetTotalMonths(DateTime From, DateTime Till)
            int MonthDiff = 0;

            for (int i = 0; i < 12; i++)
                if (From.AddMonths(i).Month == Till.Month)
                    MonthDiff = i + 1;

            return MonthDiff;

Using pg_dump to only get insert statements from one table within database

If you want to DUMP your inserts into an .sql file:

  1. cd to the location which you want to .sql file to be located
  2. pg_dump --column-inserts --data-only --table=<table> <database> > my_dump.sql

Note the > my_dump.sql command. This will put everything into a sql file named my_dump

Catch Ctrl-C in C

@Peter Varo updated Dirk's answer, but Dirk rejected the change. Here's the new answer by Peter:

Although the above snippet is a correct example, one should use the more modern types and guarantees provided by the later standards if possible. Therefore, here is a safer and modern alternative for those who are seeking for the and conforming implementation:

#include <signal.h>
#include <stdlib.h>
#include <stdio.h>

static volatile sig_atomic_t keep_running = 1;

static void sig_handler(int _)
    keep_running = 0;

int main(void)
    signal(SIGINT, sig_handler);

    while (keep_running)
        puts("Still running...");

    puts("Stopped by signal `SIGINT'");
    return EXIT_SUCCESS;

C11 Standard: 7.14§2 The header <signal.h> declare a type ... sig_atomic_t which is the (possibly volatile-qualified) integer type of an object that can be accessed as an atomic entity, even in the presence of asynchronous interrupts.


C11 Standard:§5 If the signal occurs other than as the result of calling the abort or raise function, the behavior is undefined if the signal handler refers to any object with static or thread storage duration that is not a lock-free atomic object other than by assigning a value to an object declared as volatile sig_atomic_t...

Label points in geom_point

Instead of using the ifelse as in the above example, one can also prefilter the data prior to labeling based on some threshold values, this saves a lot of work for the plotting device:

xlimit <- 36
ylimit <- 24
    geom_label(data=myData[myData$myX > xlimit & myData$myY> ylimit,], aes(myX,myY,myLabel))

How to window.scrollTo() with a smooth effect

2018 Update

Now you can use just window.scrollTo({ top: 0, behavior: 'smooth' }) to get the page scrolled with a smooth effect.

const btn = document.getElementById('elem');_x000D_
btn.addEventListener('click', () => window.scrollTo({_x000D_
  top: 400,_x000D_
  behavior: 'smooth',_x000D_
#x {_x000D_
  height: 1000px;_x000D_
  background: lightblue;_x000D_
<div id='x'>_x000D_
  <button id='elem'>Click to scroll</button>_x000D_

Older solutions

You can do something like this:

var btn = document.getElementById('x');_x000D_
btn.addEventListener("click", function() {_x000D_
  var i = 10;_x000D_
  var int = setInterval(function() {_x000D_
    window.scrollTo(0, i);_x000D_
    i += 10;_x000D_
    if (i >= 200) clearInterval(int);_x000D_
  }, 20);_x000D_
body {_x000D_
  background: #3a2613;_x000D_
  height: 600px;_x000D_
<button id='x'>click</button>

ES6 recursive approach:

const btn = document.getElementById('elem');_x000D_
const smoothScroll = (h) => {_x000D_
  let i = h || 0;_x000D_
  if (i < 200) {_x000D_
    setTimeout(() => {_x000D_
      window.scrollTo(0, i);_x000D_
      smoothScroll(i + 10);_x000D_
    }, 10);_x000D_
btn.addEventListener('click', () => smoothScroll());
body {_x000D_
  background: #9a6432;_x000D_
  height: 600px;_x000D_
<button id='elem'>click</button>

Unable to Resolve Module in React Native App

I had the exact same problem — fix was babel-preset-react-native-stage-0, instead of babel-preset-react-native.

What is an Intent in Android?

According to their documentation:

An Intent is an object that provides runtime binding between separate components (such as two activities). The Intent represents an app’s "intent to do something." You can use intents for a wide variety of tasks, but most often they’re used to start another activity.

Here is the link with example:

As the document describes, in order to start an activity (you also need to understand what activity is) use the intent like below

/** Called when the user clicks the Send button */
public void sendMessage(View view) {
    Intent intent = new Intent(this, DisplayMessageActivity.class);
    EditText editText = (EditText) findViewById(;
    String message = editText.getText().toString();
    intent.putExtra(EXTRA_MESSAGE, message);

How do I change the database name using MySQL?

"As long as two databases are on the same file system, you can use RENAME TABLE to move a table from one database to another"

-- ensure the char set and collate match the existing database.
SHOW VARIABLES LIKE 'character_set_database';
SHOW VARIABLES LIKE 'collation_database';

CREATE DATABASE `database2` DEFAULT CHARACTER SET = `utf8` DEFAULT COLLATE = `utf8_general_ci`;
RENAME TABLE `database1`.`table1` TO `database2`.`table1`;
RENAME TABLE `database1`.`table2` TO `database2`.`table2`;
RENAME TABLE `database1`.`table3` TO `database2`.`table3`;

C# List<> Sort by x then y

The trick is to implement a stable sort. I've created a Widget class that can contain your test data:

public class Widget : IComparable
    int x;
    int y;
    public int X
        get { return x; }
        set { x = value; }

    public int Y
        get { return y; }
        set { y = value; }

    public Widget(int argx, int argy)
        x = argx;
        y = argy;

    public int CompareTo(object obj)
        int result = 1;
        if (obj != null && obj is Widget)
            Widget w = obj as Widget;
            result = this.X.CompareTo(w.X);
        return result;

    static public int Compare(Widget x, Widget y)
        int result = 1;
        if (x != null && y != null)                
            result = x.CompareTo(y);
        return result;

I implemented IComparable, so it can be unstably sorted by List.Sort().

However, I also implemented the static method Compare, which can be passed as a delegate to a search method.

I borrowed this insertion sort method from C# 411:

 public static void InsertionSort<T>(IList<T> list, Comparison<T> comparison)
            int count = list.Count;
            for (int j = 1; j < count; j++)
                T key = list[j];

                int i = j - 1;
                for (; i >= 0 && comparison(list[i], key) > 0; i--)
                    list[i + 1] = list[i];
                list[i + 1] = key;

You would put this in the sort helpers class that you mentioned in your question.

Now, to use it:

    static void Main(string[] args)
        List<Widget> widgets = new List<Widget>();

        widgets.Add(new Widget(0, 1));
        widgets.Add(new Widget(1, 1));
        widgets.Add(new Widget(0, 2));
        widgets.Add(new Widget(1, 2));

        InsertionSort<Widget>(widgets, Widget.Compare);

        foreach (Widget w in widgets)
            Console.WriteLine(w.X + ":" + w.Y);

And it outputs:

Press any key to continue . . .

This could probably be cleaned up with some anonymous delegates, but I'll leave that up to you.

EDIT: And NoBugz demonstrates the power of anonymous, consider mine more oldschool :P