Programs & Examples On #Right justified

Right justify is text or page formatting that aligns text along the right side of a page. This layout has a ragged right edge and a straight left edge.

Convert Int to String in Swift

let a =123456888
var str = String(a)


var str = a as! String

How do you make div elements display inline?

Try writing it like this:

div { border: 1px solid #CCC; }
    <div style="display: inline">a</div>_x000D_
    <div style="display: inline">b</div>_x000D_
    <div style="display: inline">c</div>

How to enable PHP short tags?

As simple, as that, follow the following steps:

  1. Go to php.ini file
  2. Find short_open_tag and set it to on

    short_open_tag = On
  3. Restart the server

Can't concat bytes to str

subprocess.check_output() returns a bytestring.

In Python 3, there's no implicit conversion between unicode (str) objects and bytes objects. If you know the encoding of the output, you can .decode() it to get a string, or you can turn the \n you want to add to bytes with "\n".encode('ascii')

Trying to get property of non-object in

$sidemenu is not an object, so you can't call methods on it. It is probably not being sent to your view, or $sidemenus is empty.

How to create a zip file in Java

public static void main(String args[])
    omtZip("res/", "");
public static void omtZip(String path,String outputFile)
    final int BUFFER = 2048;
    boolean isEntry = false;
    ArrayList<String> directoryList = new ArrayList<String>();
    File f = new File(path);
    try {
            FileOutputStream fos = new FileOutputStream(outputFile);
            ZipOutputStream zos = new ZipOutputStream(new BufferedOutputStream(fos));
            byte data[] = new byte[BUFFER];

               //This is Directory
                    String directoryName = "";
                    if(directoryList.size() > 0)
                        directoryName = directoryList.get(0);
                        System.out.println("Directory Name At 0 :"+directoryName);
                    String fullPath = path+directoryName;
                    File fileList = null;
                    if(directoryList.size() == 0)
                        //Main path (Root Directory)
                        fileList = f;
                        //Child Directory
                        fileList = new File(fullPath);
                    String[] filesName = fileList.list();

                    int totalFiles = filesName.length;
                    for(int i = 0 ; i < totalFiles ; i++)
                        String name = filesName[i];
                        File filesOrDir = new File(fullPath+name);
                            System.out.println("New Directory Entry :"+directoryName+name+"/");
                            ZipEntry entry = new ZipEntry(directoryName+name+"/");
                            isEntry = true;
                            System.out.println("New File Entry :"+directoryName+name);
                            ZipEntry entry = new ZipEntry(directoryName+name);
                            isEntry = true;
                            FileInputStream fileInputStream = new FileInputStream(filesOrDir);
                            BufferedInputStream bufferedInputStream = new BufferedInputStream(fileInputStream, BUFFER);
                            int size = -1;
                            while(  (size =, 0, BUFFER)) != -1  )
                                zos.write(data, 0, size);
                    if(directoryList.size() > 0 && directoryName.trim().length() > 0)
                        System.out.println("Directory removed :"+directoryName);

                }while(directoryList.size() > 0);
                //This is File
                //Zip this file
                System.out.println("Zip this file :"+f.getPath());
                FileInputStream fis = new FileInputStream(f);
                BufferedInputStream bis = new BufferedInputStream(fis,BUFFER);
                ZipEntry entry = new ZipEntry(f.getName());
                isEntry = true;
                int size = -1 ;
                while(( size =,0,BUFFER)) != -1)
                    zos.write(data, 0, size);

                zos = null;
                System.out.println("No Entry Found in Zip");
        }catch(Exception e)
        System.out.println("File or Directory not found");


How can I merge two commits into one if I already started rebase?

$ git rebase --abort

Run this code at any time if you want to undo the git rebase

$ git rebase -i HEAD~2

To reapply last two commits. The above command will open a code editor

  • [ The latest commit will be at the bottom ]. Change the last commit to squash(s). Since squash will meld with previous commit.
  • Then press esc key and type :wq to save and close

After :wq you will be in active rebase mode

Note: You'll get another editor if no warning/error messages, If there is an error or warning another editor will not show, you may abort by runnning $ git rebase --abort if you see an error or warning else just continue by running $ git rebase --continue

You will see your 2 commit message. Choose one or write your own commit message, save and quit [:wq]

Note 2: You may need to force push your changes to the remote repo if you run rebase command

$ git push -f

$ git push -f origin master

How to trim a string after a specific character in java

There are many good answers, but I would use StringUtils from commons-lang. I find StringUtils.substringBefore() more readable than the alternatives:

String result = StringUtils.substringBefore("34.1 -118.33\n<!--ABCDEFG-->", "\n");

Change link color of the current page with CSS

include this! on your page where you want to change the colors save as .php

<?php include("includes/navbar.php"); ?>

then add a new file in an includes folder.


<div <?php //Using REQUEST_URI

$currentpage = $_SERVER['REQUEST_URI'];

if(preg_match("/index/i", $currentpage)||($currentpage=="/"))
    echo " class=\"navbarorange/*the css class for your nav div*/\" ";
elseif(preg_match("/about/*or second page name*//i", $currentpage))
    echo " class=\"navbarpink\" ";
elseif(preg_match("/contact/* or edit 3rd page name*//i", $currentpage))
    echo " class=\"navbargreen\" ";?> >

Div width 100% minus fixed amount of pixels

New way I've just stumbled upon: css calc():

.calculated-width {
    width: -webkit-calc(100% - 100px);
    width:    -moz-calc(100% - 100px);
    width:         calc(100% - 100px);

Source: css width 100% minus 100px

SQL Query - Using Order By in UNION

The second table cannot include the table name in the ORDER BY clause.


SELECT table1.field1 FROM table1 ORDER BY table1.field1
SELECT table2.field1 FROM table2 ORDER BY field1

Does not throw an exception

What is the purpose of the word 'self'?

Python is not a language built for Object Oriented Programming unlike Java or C++.

When calling a static method in Python, one simply writes a method with regular arguments inside it.

class Animal():
    def staticMethod():
        print "This is a static method"

However, an object method, which requires you to make a variable, which is an Animal, in this case, needs the self argument

class Animal():
    def objectMethod(self):
        print "This is an object method which needs an instance of a class"

The self method is also used to refer to a variable field within the class.

class Animal():
    #animalName made in constructor
    def Animal(self):
        self.animalName = "";

    def getAnimalName(self):
        return self.animalName

In this case, self is referring to the animalName variable of the entire class. REMEMBER: If you have a variable within a method, self will not work. That variable is simply existent only while that method is running. For defining fields (the variables of the entire class), you have to define them OUTSIDE the class methods.

If you don't understand a single word of what I am saying, then Google "Object Oriented Programming." Once you understand this, you won't even need to ask that question :).

How to efficiently concatenate strings in go

Note added in 2018

From Go 1.10 there is a strings.Builder type, please take a look at this answer for more detail.

Pre-201x answer

The benchmark code of @cd1 and other answers are wrong. b.N is not supposed to be set in benchmark function. It's set by the go test tool dynamically to determine if the execution time of the test is stable.

A benchmark function should run the same test b.N times and the test inside the loop should be the same for each iteration. So I fix it by adding an inner loop. I also add benchmarks for some other solutions:

package main

import (

const (
    sss = "xfoasneobfasieongasbg"
    cnt = 10000

var (
    bbb      = []byte(sss)
    expected = strings.Repeat(sss, cnt)

func BenchmarkCopyPreAllocate(b *testing.B) {
    var result string
    for n := 0; n < b.N; n++ {
        bs := make([]byte, cnt*len(sss))
        bl := 0
        for i := 0; i < cnt; i++ {
            bl += copy(bs[bl:], sss)
        result = string(bs)
    if result != expected {
        b.Errorf("unexpected result; got=%s, want=%s", string(result), expected)

func BenchmarkAppendPreAllocate(b *testing.B) {
    var result string
    for n := 0; n < b.N; n++ {
        data := make([]byte, 0, cnt*len(sss))
        for i := 0; i < cnt; i++ {
            data = append(data, sss...)
        result = string(data)
    if result != expected {
        b.Errorf("unexpected result; got=%s, want=%s", string(result), expected)

func BenchmarkBufferPreAllocate(b *testing.B) {
    var result string
    for n := 0; n < b.N; n++ {
        buf := bytes.NewBuffer(make([]byte, 0, cnt*len(sss)))
        for i := 0; i < cnt; i++ {
        result = buf.String()
    if result != expected {
        b.Errorf("unexpected result; got=%s, want=%s", string(result), expected)

func BenchmarkCopy(b *testing.B) {
    var result string
    for n := 0; n < b.N; n++ {
        data := make([]byte, 0, 64) // same size as bootstrap array of bytes.Buffer
        for i := 0; i < cnt; i++ {
            off := len(data)
            if off+len(sss) > cap(data) {
                temp := make([]byte, 2*cap(data)+len(sss))
                copy(temp, data)
                data = temp
            data = data[0 : off+len(sss)]
            copy(data[off:], sss)
        result = string(data)
    if result != expected {
        b.Errorf("unexpected result; got=%s, want=%s", string(result), expected)

func BenchmarkAppend(b *testing.B) {
    var result string
    for n := 0; n < b.N; n++ {
        data := make([]byte, 0, 64)
        for i := 0; i < cnt; i++ {
            data = append(data, sss...)
        result = string(data)
    if result != expected {
        b.Errorf("unexpected result; got=%s, want=%s", string(result), expected)

func BenchmarkBufferWrite(b *testing.B) {
    var result string
    for n := 0; n < b.N; n++ {
        var buf bytes.Buffer
        for i := 0; i < cnt; i++ {
        result = buf.String()
    if result != expected {
        b.Errorf("unexpected result; got=%s, want=%s", string(result), expected)

func BenchmarkBufferWriteString(b *testing.B) {
    var result string
    for n := 0; n < b.N; n++ {
        var buf bytes.Buffer
        for i := 0; i < cnt; i++ {
        result = buf.String()
    if result != expected {
        b.Errorf("unexpected result; got=%s, want=%s", string(result), expected)

func BenchmarkConcat(b *testing.B) {
    var result string
    for n := 0; n < b.N; n++ {
        var str string
        for i := 0; i < cnt; i++ {
            str += sss
        result = str
    if result != expected {
        b.Errorf("unexpected result; got=%s, want=%s", string(result), expected)

Environment is OS X 10.11.6, 2.2 GHz Intel Core i7

Test results:

BenchmarkCopyPreAllocate-8         20000             84208 ns/op          425984 B/op          2 allocs/op
BenchmarkAppendPreAllocate-8       10000            102859 ns/op          425984 B/op          2 allocs/op
BenchmarkBufferPreAllocate-8       10000            166407 ns/op          426096 B/op          3 allocs/op
BenchmarkCopy-8                    10000            160923 ns/op          933152 B/op         13 allocs/op
BenchmarkAppend-8                  10000            175508 ns/op         1332096 B/op         24 allocs/op
BenchmarkBufferWrite-8             10000            239886 ns/op          933266 B/op         14 allocs/op
BenchmarkBufferWriteString-8       10000            236432 ns/op          933266 B/op         14 allocs/op
BenchmarkConcat-8                     10         105603419 ns/op        1086685168 B/op    10000 allocs/op


  1. CopyPreAllocate is the fastest way; AppendPreAllocate is pretty close to No.1, but it's easier to write the code.
  2. Concat has really bad performance both for speed and memory usage. Don't use it.
  3. Buffer#Write and Buffer#WriteString are basically the same in speed, contrary to what @Dani-Br said in the comment. Considering string is indeed []byte in Go, it makes sense.
  4. bytes.Buffer basically use the same solution as Copy with extra book keeping and other stuff.
  5. Copy and Append use a bootstrap size of 64, the same as bytes.Buffer
  6. Append use more memory and allocs, I think it's related to the grow algorithm it use. It's not growing memory as fast as bytes.Buffer


  1. For simple task such as what OP wants, I would use Append or AppendPreAllocate. It's fast enough and easy to use.
  2. If need to read and write the buffer at the same time, use bytes.Buffer of course. That's what it's designed for.

How to remove white space characters from a string in SQL Server

Looks like the invisible character -


Try this

select REPLACE(ProductAlternateKey, ' ', '@')
--type ALT+255 instead of space for the second expression in REPLACE 
from DimProducts
where ProductAlternateKey  like '46783815%'


Edit: Based on ASCII() results, try ALT+10 - use numeric keypad

How to launch PowerShell (not a script) from the command line

Set the default console colors and fonts:
From Windows PowerShell Cookbook (O'Reilly)
by Lee Holmes (

Set-StrictMode -Version Latest

Set-Location HKCU:\Console
New-Item '.\%SystemRoot%_system32_WindowsPowerShell_v1.0_powershell.exe'
Set-Location '.\%SystemRoot%_system32_WindowsPowerShell_v1.0_powershell.exe'

New-ItemProperty . ColorTable00 -type DWORD -value 0x00562401
New-ItemProperty . ColorTable07 -type DWORD -value 0x00f0edee
New-ItemProperty . FaceName -type STRING -value "Lucida Console"
New-ItemProperty . FontFamily -type DWORD -value 0x00000036
New-ItemProperty . FontSize -type DWORD -value 0x000c0000
New-ItemProperty . FontWeight -type DWORD -value 0x00000190
New-ItemProperty . HistoryNoDup -type DWORD -value 0x00000000
New-ItemProperty . QuickEdit -type DWORD -value 0x00000001
New-ItemProperty . ScreenBufferSize -type DWORD -value 0x0bb80078
New-ItemProperty . WindowSize -type DWORD -value 0x00320078

WPF MVVM ComboBox SelectedItem or SelectedValue not working

I solved the problem by adding dispatcher in UserControl_Loaded event

 Dispatcher.BeginInvoke(DispatcherPriority.Loaded, new Action(() =>
     combobox.SelectedIndex = 0;

How to use timeit module

The built-in timeit module works best from the IPython command line.

To time functions from within a module:

from timeit import default_timer as timer
import sys

def timefunc(func, *args, **kwargs):
    """Time a function. 


    Usage example:
        timeit(myfunc, 1, b=2)
        iterations = kwargs.pop('iterations')
    except KeyError:
        iterations = 3
    elapsed = sys.maxsize
    for _ in range(iterations):
        start = timer()
        result = func(*args, **kwargs)
        elapsed = min(timer() - start, elapsed)
    print(('Best of {} {}(): {:.9f}'.format(iterations, func.__name__, elapsed)))
    return result

What does "Object reference not set to an instance of an object" mean?

Not to be blunt but it means exactly what it says. One of your object references is NULL. You'll see this when you try and access the property or method of a NULL'd object.

How to clear mysql screen console in windows?

The bug on Windows which most people are talking is probably fixed. Ctrl + L is works for clearing the screen on Windows 10 [Mysql 8]

Passing a method parameter using Task.Factory.StartNew

Construct the first parameter as an instance of Action, e.g.

var inputID = 123;
var col = new BlockingDataCollection();
var task = Task.Factory.StartNew(
    () => CheckFiles(inputID, col),

How to save/restore serializable object to/from file?

You can use JsonConvert from Newtonsoft library. To serialize an object and write to a file in json format:

File.WriteAllText(filePath, JsonConvert.SerializeObject(obj));

And to deserialize it back into object:

var obj = JsonConvert.DeserializeObject<ObjType>(File.ReadAllText(filePath));

Get the cell value of a GridView row

string id;
foreach (GridViewRow rows in grd.Rows)
   TextBox lblStrucID = (TextBox)rows.FindControl("grdtext");

Force unmount of NFS-mounted directory

You might try a lazy unmount:

umount -l

How can a file be copied?

from subprocess import call
call("cp -p <file> <file>", shell=True)

Delete all rows with timestamp older than x days

DELETE FROM on_search 

groovy.lang.MissingPropertyException: No such property: jenkins for class: groovy.lang.Binding

in my case I have used - (Hyphen) in my script name in case of Jenkinsfile Library. Got resolved after replacing Hyphen(-) with Underscore(_)

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

Break out the LIKE clauses into 2 separate statements, i.e.:

(fieldname1 LIKE '%this%' or fieldname1 LIKE '%that%' ) and something=else

How to set column header text for specific column in Datagridview C#

Dg_View.Columns.Add("userid","User Id");
Dg_View.Columns[0].Width = 100;

Dg_View.Columns.Add("username", "User name");
Dg_View.Columns[0].Width = 100;

@RequestParam vs @PathVariable

If the URL http://localhost:8080/MyApp/user/1234/invoices?date=12-05-2013 gets the invoices for user 1234 on December 5th, 2013, the controller method would look like:

@RequestMapping(value="/user/{userId}/invoices", method = RequestMethod.GET)
public List<Invoice> listUsersInvoices(
            @PathVariable("userId") int user,
            @RequestParam(value = "date", required = false) Date dateOrNull) {

Also, request parameters can be optional, and as of Spring 4.3.3 path variables can be optional as well. Beware though, this might change the URL path hierarchy and introduce request mapping conflicts. For example, would /user/invoices provide the invoices for user null or details about a user with ID "invoices"?

Hide keyboard in react-native

import {Keyboard} from 'react-native';

use Keyboard.dismiss() to hide your keyboard in any onClick or onPress event.

How to turn a string formula into a "real" formula

Just for fun, I found an interesting article here, to use a somehow hidden evaluate function that does exist in Excel. The trick is to assign it to a name, and use the name in your cells, because EVALUATE() would give you an error msg if used directly in a cell. I tried and it works! You can use it with a relative name, if you want to copy accross rows if a sheet.

Fastest JavaScript summation

You should be able to use reduce.

var sum = array.reduce(function(pv, cv) { return pv + cv; }, 0);


And with arrow functions introduced in ES6, it's even simpler:

sum = array.reduce((pv, cv) => pv + cv, 0);

`export const` vs. `export default` in ES6

export default affects the syntax when importing the exported "thing", when allowing to import, whatever has been exported, by choosing the name in the import itself, no matter what was the name when it was exported, simply because it's marked as the "default".

A useful use case, which I like (and use), is allowing to export an anonymous function without explicitly having to name it, and only when that function is imported, it must be given a name:


Export 2 functions, one is default:

export function divide( x ){
    return x / 2;

// only one 'default' function may be exported and the rest (above) must be named
export default function( x ){  // <---- declared as a default function
    return x * x;

Import the above functions. Making up a name for the default one:

// The default function should be the first to import (and named whatever)
import square, {divide} from './module_1.js'; // I named the default "square" 

console.log( square(2), divide(2) ); // 4, 1

When the {} syntax is used to import a function (or variable) it means that whatever is imported was already named when exported, so one must import it by the exact same name, or else the import wouldn't work.

Erroneous Examples:

  1. The default function must be first to import

    import {divide}, square from './module_1.js
  2. divide_1 was not exported in module_1.js, thus nothing will be imported

    import {divide_1} from './module_1.js
  3. square was not exported in module_1.js, because {} tells the engine to explicitly search for named exports only.

    import {square} from './module_1.js

Run a single migration file

If you want to run a specific migration, do

$ rake db:migrate:up VERSION=20080906120000

If you want to run migrations multiple times, do

# use the STEP parameter if you need to go more than one version back
$ rake db:migrate:redo STEP=3

If you want to run a single migration multiple times, do

# this is super useful
$ rake db:migrate:redo VERSION=20080906120000

(you can find the version number in the filename of your migration)

Edit: You can also simply rename your migration file, Eg:

20151013131830_my_migration.rb -> 20151013131831_my_migration.rb

Then migrate normally, this will treat the migration as a new one (usefull if you want to migrate on a remote environment (such as staging) on which you have less control.

Edit 2: You can also just nuke the migration entry in the database. Eg:

rails_c> q = "delete from schema_migrations where version = '20151013131830'"
rails_c> ActiveRecord::Base.connection.execute(q)

rake db:migrate will then rerun the up method of the nuked migrations.

List of All Locales and Their Short Codes?

Language List

List of all languages with names and ISO 639-1 codes in all languages and all data formats.

Formats Available

  • Text
  • JSON
  • YAML
  • XML
  • HTML
  • CSV
  • SQL (MySQL, PostgreSQL, SQLite)
  • PHP

Jquery get input array field

Put the input name between single quotes so that the brackets [] are treated as a string

var multi_members="";
$("input[name='bayi[]']:checked:enabled").each(function() {

How do you decompile a swf file

I've used Sothink SWF decompiler a couple of times, the only problem is that as project gets more complex, the output of decompiler gets harder to compile back again. But it ensures that you can get your .as files most of the time, compilable fla is a question.

Sothink SWF Decompiler

nil detection in Go

The language spec mentions comparison operators' behaviors:

comparison operators

In any comparison, the first operand must be assignable to the type of the second operand, or vice versa.


A value x is assignable to a variable of type T ("x is assignable to T") in any of these cases:

  • x's type is identical to T.
  • x's type V and T have identical underlying types and at least one of V or T is not a named type.
  • T is an interface type and x implements T.
  • x is a bidirectional channel value, T is a channel type, x's type V and T have identical element types, and at least one of V or T is not a named type.
  • x is the predeclared identifier nil and T is a pointer, function, slice, map, channel, or interface type.
  • x is an untyped constant representable by a value of type T.

How we can bold only the name in table td tag not the value

I would use to table header tag below for a text in a table to make it standout from the rest of the table content.


    <td>98cm x 71cm</td>

Should we pass a shared_ptr by reference or by value?

Here's Herb Sutter's take

Guideline: Don’t pass a smart pointer as a function parameter unless you want to use or manipulate the smart pointer itself, such as to share or transfer ownership.

Guideline: Express that a function will store and share ownership of a heap object using a by-value shared_ptr parameter.

Guideline: Use a non-const shared_ptr& parameter only to modify the shared_ptr. Use a const shared_ptr& as a parameter only if you’re not sure whether or not you’ll take a copy and share ownership; otherwise use widget* instead (or if not nullable, a widget&).

How do I use Bash on Windows from the Visual Studio Code integrated terminal?

I tried the above answers as of vscode 1.42.1 and they worked inasmuch as to get me a git bash terminal. So, bottom line this setting works just for opening a bash shell from terminal:

"": "C:\\Program Files\\Git\\bin\\bash.exe"

However it has the unwanted side effect of also being the shell used to build things and that breaks the MS C++ chain because the \ character used for path separator is understood by bash as an escape character. The complete fix for me then required me to add this extra variable, setting it to powershell:

"": "C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe"

Now, I can have my bash terminal and Ctrl-Shift-B or F5 work without problems.

Oh, and as other posters mentioned, the source for this information is VSCode's documentation.

How to handle "Uncaught (in promise) DOMException: play() failed because the user didn't interact with the document first." on Desktop with Chrome 66?

Chrome needs a user interaction for the video to be autoplayed or played via js ( But the interaction can be of any kind, in any moment. If you just click random on the page, the video will autoplay. I resolved then, adding a button (only on chrome browsers) that says "enable video autoplay". The button does nothing, but just clicking it, is the required user interaction for any further video.

SQL split values to multiple rows

        declare r_len integer;
        declare r_id integer;
        declare r_val varchar(20);
        declare i integer;
        DECLARE found_row int(10);
        DECLARE row CURSOR FOR select length(replace(val,"|","")),id,val from split;
        create table x(id int,name varchar(20));
      open row;
            select FOUND_ROWS() into found_row ;
            read_loop: LOOP
                IF found_row = 0 THEN
                         LEAVE read_loop;
                END IF;
            set i = 1;  
            FETCH row INTO r_len,r_id,r_val;
            label1: LOOP        
                IF i <= r_len THEN
                  insert into x values( r_id,SUBSTRING(replace(r_val,"|",""),i,1));
                  SET i = i + 1;
                  ITERATE label1;
                END IF;
                LEAVE label1;
            END LOOP label1;
            set found_row = found_row - 1;
            END LOOP;
        close row;
        select * from x;
        drop table x;

mysql select from n last rows

because it is autoincrement, here's my take:

Select * from tbl 
where certainconditionshere 
and autoincfield >= (select max(autoincfield) from tbl) - $n

How to insert an object in an ArrayList at a specific position

Note that when you insert into a List at a position, you are really inserting at a dynamic position within the List's current elements. See here:

package com.tutorialspoint;

import java.util.ArrayList;

public class ArrayListDemo {
   public static void main(String[] args) {

      // create an empty array list with an initial capacity
      ArrayList<Integer> arrlist = new ArrayList<Integer>(5);

      // use add() method to add elements in the list
      arrlist.add(15, 15);
      arrlist.add(22, 22);
      arrlist.add(30, 30);
      arrlist.add(40, 40);

      // adding element 25 at third position
      arrlist.add(2, 25);

      // let us print all the elements available in list
      for (Integer number : arrlist) {
         System.out.println("Number = " + number);

$javac com/tutorialspoint/

$java -Xmx128M -Xms16M com/tutorialspoint/ArrayListDemo

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 15, Size: 0
    at java.util.ArrayList.rangeCheckForAdd(
    at java.util.ArrayList.add(
    at com.tutorialspoint.ArrayListDemo.main(

Java: Replace all ' in a string with \'

You can use apache's commons-text library (instead of commons-lang):

Example code:



compile 'org.apache.commons:commons-text:1.8'



Types in MySQL: BigInt(20) vs Int(20)

The number in parentheses in a type declaration is display width, which is unrelated to the range of values that can be stored in a data type. Just because you can declare Int(20) does not mean you can store values up to 10^20 in it:

[...] This optional display width may be used by applications to display integer values having a width less than the width specified for the column by left-padding them with spaces. ...

The display width does not constrain the range of values that can be stored in the column, nor the number of digits that are displayed for values having a width exceeding that specified for the column. For example, a column specified as SMALLINT(3) has the usual SMALLINT range of -32768 to 32767, and values outside the range allowed by three characters are displayed using more than three characters.

For a list of the maximum and minimum values that can be stored in each MySQL datatype, see here.

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

This solved the problem for me!

Without the need for an external div. Just apply it to your given text box.

box-sizing: border-box; 

With this property "The width and height properties (and min/max properties) includes content, padding and border, but not the margin"

See description of property at w3schools.

Hope this helps someone!

iPhone - Get Position of UIView within entire UIWindow

For me this code worked best:

private func getCoordinate(_ view: UIView) -> CGPoint {
    var x = view.frame.origin.x
    var y = view.frame.origin.y
    var oldView = view

    while let superView = oldView.superview {
        x += superView.frame.origin.x
        y += superView.frame.origin.y
        if is UIViewController {
            break //superView is the rootView of a UIViewController
        oldView = superView

    return CGPoint(x: x, y: y)

Creating a PHP header/footer

You can do it by using include_once() function in php. Construct a header part in the name of header.php and construct the footer part by footer.php. Finally include all the content in one file.

For example:


<link href="sample.css">



So the final files look like


body content(The body content changes based on the file dynamically)


Rails select helper - Default selected value, how?

The problem with all of these answers is they set the field to the default value even if you're trying to edit your record.

You need to set the default to your existing value and then only set it to the actual default if you don't have a value. Like so: :field, options_for_select(value_array, f.object.field || default_value)

For anyone not familiar with f.object.field you always use f.object then add your field name to the end of that.

Do fragments really need an empty constructor?

Yes they do.

You shouldn't really be overriding the constructor anyway. You should have a newInstance() static method defined and pass any parameters via arguments (bundle)

For example:

public static final MyFragment newInstance(int title, String message) {
    MyFragment f = new MyFragment();
    Bundle bdl = new Bundle(2);
    bdl.putInt(EXTRA_TITLE, title);
    bdl.putString(EXTRA_MESSAGE, message);
    return f;

And of course grabbing the args this way:

public void onCreate(Bundle savedInstanceState) {
    title = getArguments().getInt(EXTRA_TITLE);
    message = getArguments().getString(EXTRA_MESSAGE);


Then you would instantiate from your fragment manager like so:

public void onCreate(Bundle savedInstanceState) {
    if (savedInstanceState == null){
            .replace(, MyFragment.newInstance(
                "Oh no, an error occurred!")

This way if detached and re-attached the object state can be stored through the arguments. Much like bundles attached to Intents.

Reason - Extra reading

I thought I would explain why for people wondering why.

If you check:

You will see the instantiate(..) method in the Fragment class calls the newInstance method:

public static Fragment instantiate(Context context, String fname, @Nullable Bundle args) {
    try {
        Class<?> clazz = sClassMap.get(fname);
        if (clazz == null) {
            // Class not found in the cache, see if it's real, and try to add it
            clazz = context.getClassLoader().loadClass(fname);
            if (!Fragment.class.isAssignableFrom(clazz)) {
                throw new InstantiationException("Trying to instantiate a class " + fname
                        + " that is not a Fragment", new ClassCastException());
            sClassMap.put(fname, clazz);
        Fragment f = (Fragment) clazz.getConstructor().newInstance();
        if (args != null) {
        return f;
    } catch (ClassNotFoundException e) {
        throw new InstantiationException("Unable to instantiate fragment " + fname
                + ": make sure class name exists, is public, and has an"
                + " empty constructor that is public", e);
    } catch (java.lang.InstantiationException e) {
        throw new InstantiationException("Unable to instantiate fragment " + fname
                + ": make sure class name exists, is public, and has an"
                + " empty constructor that is public", e);
    } catch (IllegalAccessException e) {
        throw new InstantiationException("Unable to instantiate fragment " + fname
                + ": make sure class name exists, is public, and has an"
                + " empty constructor that is public", e);
    } catch (NoSuchMethodException e) {
        throw new InstantiationException("Unable to instantiate fragment " + fname
                + ": could not find Fragment constructor", e);
    } catch (InvocationTargetException e) {
        throw new InstantiationException("Unable to instantiate fragment " + fname
                + ": calling Fragment constructor caused an exception", e);
} Explains why, upon instantiation it checks that the accessor is public and that that class loader allows access to it.

It's a pretty nasty method all in all, but it allows the FragmentManger to kill and recreate Fragments with states. (The Android subsystem does similar things with Activities).

Example Class

I get asked a lot about calling newInstance. Do not confuse this with the class method. This whole class example should show the usage.

 * Created by chris on 21/11/2013
public class StationInfoAccessibilityFragment extends BaseFragment implements JourneyProviderListener {

    public static final StationInfoAccessibilityFragment newInstance(String crsCode) {
        StationInfoAccessibilityFragment fragment = new StationInfoAccessibilityFragment();

        final Bundle args = new Bundle(1);
        args.putString(EXTRA_CRS_CODE, crsCode);

        return fragment;

    // Views
    LinearLayout mLinearLayout;

     * Layout Inflater
    private LayoutInflater mInflater;
     * Station Crs Code
    private String mCrsCode;

    public void onCreate(Bundle savedInstanceState) {
        mCrsCode = getArguments().getString(EXTRA_CRS_CODE);

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        mInflater = inflater;
        return inflater.inflate(R.layout.fragment_station_accessibility, container, false);

    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mLinearLayout = (LinearLayout)view.findViewBy(;
        //Do stuff

    public void onResume() {

    // Other methods etc...

C free(): invalid pointer

You're attempting to free something that isn't a pointer to a "freeable" memory address. Just because something is an address doesn't mean that you need to or should free it.

There are two main types of memory you seem to be confusing - stack memory and heap memory.

  • Stack memory lives in the live span of the function. It's temporary space for things that shouldn't grow too big. When you call the function main, it sets aside some memory for your variables you've declared (p,token, and so on).

  • Heap memory lives from when you malloc it to when you free it. You can use much more heap memory than you can stack memory. You also need to keep track of it - it's not easy like stack memory!

You have a few errors:

  • You're trying to free memory that's not heap memory. Don't do that.

  • You're trying to free the inside of a block of memory. When you have in fact allocated a block of memory, you can only free it from the pointer returned by malloc. That is to say, only from the beginning of the block. You can't free a portion of the block from the inside.

For your bit of code here, you probably want to find a way to copy relevant portion of memory to somewhere else...say another block of memory you've set aside. Or you can modify the original string if you want (hint: char value 0 is the null terminator and tells functions like printf to stop reading the string).

EDIT: The malloc function does allocate heap memory*.

"9.9.1 The malloc and free Functions

The C standard library provides an explicit allocator known as the malloc package. Programs allocate blocks from the heap by calling the malloc function."

~Computer Systems : A Programmer's Perspective, 2nd Edition, Bryant & O'Hallaron, 2011

EDIT 2: * The C standard does not, in fact, specify anything about the heap or the stack. However, for anyone learning on a relevant desktop/laptop machine, the distinction is probably unnecessary and confusing if anything, especially if you're learning about how your program is stored and executed. When you find yourself working on something like an AVR microcontroller as H2CO3 has, it is definitely worthwhile to note all the differences, which from my own experience with embedded systems, extend well past memory allocation.

Definition of "downstream" and "upstream"

That's a bit of informal terminology.

As far as Git is concerned, every other repository is just a remote.

Generally speaking, upstream is where you cloned from (the origin). Downstream is any project that integrates your work with other works.

The terms are not restricted to Git repositories.

For instance, Ubuntu is a Debian derivative, so Debian is upstream for Ubuntu.

Adding image to JFrame

There is no specialized image component provided in Swing (which is sad in my opinion). So, there are a few options:

  1. As @Reimeus said: Use a JLabel with an icon.
  2. Create in the window builder a JPanel, that will represent the location of the image. Then add your own custom image component to the JPanel using a few lines of code you will never have to change. They should look like this:

    JImageComponent ic = new JImageComponent(myImageGoesHere);

    where JImageComponent is a self created class that extends JComponent that overrides the paintComponent() method to draw the image.

html/css buttons that scroll down to different div sections on a webpage

try this:

<input type="button" onClick="document.getElementById('middle').scrollIntoView();" />

Find the directory part (minus the filename) of a full path in access 97

This seems to work. The above doesn't in Excel 2010.

Function StripFilename(sPathFile As String) As String
'given a full path and file, strip the filename off the end and return the path
Dim filesystem As Object

Set filesystem = CreateObject("Scripting.FilesystemObject")

StripFilename = filesystem.GetParentFolderName(sPathFile) & "\"

Exit Function

End Function

What is trunk, branch and tag in Subversion?

A trunk is considered your main code base, a branch offshoot of the trunk. Like, you create a branch if you want to implement a new feature, but don't want to affect the main trunk.

TortoiseSVN has good documentation, and a great diff tool.

I use Visual studio, and I use VisualSVN and TortoiseSVN.

How do I delete NuGet packages that are not referenced by any project in my solution?

From the Package Manager console window, often whatever command you used to install a package can be used to uninstall that package. Simply replace the INSTALL command with UNINSTALL.

For example, to install PowerTCPTelnet, the command is:

Install-Package PowerTCPTelnet -Version 4.4.9

To uninstall same, the command is:

Uninstall-Package PowerTCPTelnet -Version 4.4.9

How to allow users to check for the latest app version from inside the app?

Navigate to your play page:

Using a standard HTTP GET. Now the following jQuery finds important info for you:

Current Version


What's new

$(".recent-change").each(function() { all += $(this).text() + "\n"; })

Now that you can extract these information manually, simply make a method in your app that executes this for you.

public static String[] getAppVersionInfo(String playUrl) {
    HtmlCleaner cleaner = new HtmlCleaner();
    CleanerProperties props = cleaner.getProperties();
    try {
        URL url = new URL(playUrl);
        URLConnection conn = url.openConnection();
        TagNode node = cleaner.clean(new InputStreamReader(conn.getInputStream()));
        Object[] new_nodes = node.evaluateXPath("//*[@class='recent-change']");
        Object[] version_nodes = node.evaluateXPath("//*[@itemprop='softwareVersion']");

        String version = "", whatsNew = "";
        for (Object new_node : new_nodes) {
            TagNode info_node = (TagNode) new_node;
            whatsNew += info_node.getAllChildren().get(0).toString().trim()
                    + "\n";
        if (version_nodes.length > 0) {
            TagNode ver = (TagNode) version_nodes[0];
            version = ver.getAllChildren().get(0).toString().trim();
        return new String[]{version, whatsNew};
    } catch (IOException | XPatherException e) {
        return null;

Uses HtmlCleaner

Make multiple-select to adjust its height to fit options without scroll bar

You can only do this in Javascript/JQuery, you can do it with the following JQuery (assuming you've gave your select an id of multiselect):

$(function () {
    $("#multiSelect").css("height", parseInt($("#multiSelect option").length) * 20);


PHP 7: Missing VCRUNTIME140.dll

Visual C++ Redistributable for Visual Studio 2015 (x32 bit version) - RC.

This should correct that. You can google for what the DLL is, but that's not important.

PS: It's officially from Microsoft too:)

Where I found it: Downloads (Visual Studio)

Get list of databases from SQL Server

To exclude system databases:

SELECT [name]
FROM master.dbo.sysdatabases
WHERE dbid > 6

Edited : 2:36 PM 2/5/2013

Updated with accurate database_id, It should be greater than 4, to skip listing system databases which are having database id between 1 and 4.

FROM sys.databases d
WHERE d.database_id > 4

How to trigger Jenkins builds remotely and to pass parameters

To pass/use the variables, first create parameters in the configure section of Jenkins. Parameters that you use can be of type text, String, file, etc.

After creating them, use the variable reference in the fields you want to.

For example: I have configured/created two variables for Email-subject and Email-recipentList, and I have used their reference in the EMail-ext plugin (attached screenshot).

Enter image description here

How to JOIN three tables in Codeigniter

Try this one for data...

function get_album_data() {
    $this->db->select ( 'album.*,cat.*,s_track.*' )
        ->from ( 'albums as album' );
        ->join ( 'categories cat', 'cat.cat_id = album.cat_id')
        ->join ( 'soundtracks s_tracks ', 's_tracks.album_id = album.album_id');
    $query = $this->db->get ();
    return $query->result ();

while for datum try this...

function get_album_datum($album_id) {
    $this->db->select ( 'album.*,cat.*,s_track.*' )
        ->from ( 'albums as album' );
        ->join ( 'categories cat', 'cat.cat_id = album.cat_id')
        ->join ( 'soundtracks s_tracks ', 's_tracks.album_id = album.album_id');
    $this->db->where ( 'album.album_id', $album_id);
    $query = $this->db->get ();
    return $query->row();


Simple C example of doing an HTTP POST and consuming the response

Jerry's answer is great. However, it doesn't handle large responses. A simple change to handle this:

memset(response, 0, sizeof(response));
total = sizeof(response)-1;
received = 0;
do {
    printf("RESPONSE: %s\n", response);
    memset(response, 0, sizeof(response));
    bytes = recv(sockfd, response, 1024, 0);
    if (bytes < 0)
        printf("ERROR reading response from socket");
    if (bytes == 0)
} while (1); 

MySQL error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near

Delimiters, delimiters...

You really need them when there are multiple statements in your procedure. (in other words, do you have a ; in your code and then more statements/commands? Then, you need to use delimiters).

For such a simpler rpocedure as yours though, you could just do:

  SELECT * FROM `hs_hr_employee_leave_quota`;

Scroll part of content in fixed position container

I changed scrollable div to be with absolute position, and everything works for me

div.sidebar {
    overflow: hidden;
    background-color: green;
    padding: 5px;
    position: fixed;
    right: 20px;
    width: 40%;
    top: 30px;
    padding: 20px;
    bottom: 30%;
div#fixed {
    background: #76a7dc;
    color: #fff;
    height: 30px;

div#scrollable {
    overflow-y: scroll;
    background: lightblue;

    position: absolute;

DEMO with two scrollable divs

TypeError: can't use a string pattern on a bytes-like object in re.findall()

You want to convert html (a byte-like object) into a string using .decode, e.g. html ='utf-8').

See Convert bytes to a Python String

In the shell, what does " 2>&1 " mean?

People, always remember paxdiablo's hint about the current location of the redirection target... It is important.

My personal mnemonic for the 2>&1 operator is this:

  • Think of & as meaning 'and' or 'add' (the character is an ampers-and, isn't it?)
  • So it becomes: 'redirect 2 (stderr) to where 1 (stdout) already/currently is and add both streams'.

The same mnemonic works for the other frequently used redirection too, 1>&2:

  • Think of & meaning and or add... (you get the idea about the ampersand, yes?)
  • So it becomes: 'redirect 1 (stdout) to where 2 (stderr) already/currently is and add both streams'.

And always remember: you have to read chains of redirections 'from the end', from right to left (not from left to right).

How can I check if given int exists in array?

I think you are looking for std::any_of, which will return a true/false answer to detect if an element is in a container (array, vector, deque, etc.)

int val = SOME_VALUE; // this is the value you are searching for
bool exists = std::any_of(std::begin(myArray), std::end(myArray), [&](int i)
    return i == val;

If you want to know where the element is, std::find will return an iterator to the first element matching whatever criteria you provide (or a predicate you give it).

int val = SOME_VALUE;
int* pVal = std::find(std::begin(myArray), std::end(myArray), val);
if (pVal == std::end(myArray))
    // not found
    // found

Inserting a Python datetime.datetime object into MySQL

If you're just using a python (not a full datetime.datetime), just cast the date as a string. This is very simple and works for me (mysql, python 2.7, Ubuntu). The column published_date is a MySQL date field, the python variable publish_date is

# make the record for the passed link info
sql_stmt = "INSERT INTO snippet_links (" + \
    "link_headline, link_url, published_date, author, source, coco_id, link_id)" + \
    "VALUES(%s, %s, %s, %s, %s, %s, %s) ;"

sql_data = ( title, link, str(publish_date), \
             author, posted_by, \
             str(coco_id), str(link_id) )

    dbc.execute(sql_stmt, sql_data )
except Exception, e:

SQL Inner Join On Null Values

This article has a good discussion on this issue. You can use

                       SELECT y.QID);

adding child nodes in treeview

void treeView(string [] LineString)
        int line = LineString.Length;
        string AssmMark = "";
        string PartMark = "";
        TreeNode aNode;
        TreeNode pNode;
        for ( int i=0 ; i<line ; i++){
            string sLine = LineString[i];
            if ( sLine.StartsWith("ASSEMBLY:") ){
                sLine  = sLine.Replace("ASSEMBLY:","");
                string[] aData = sLine.Split(new char[] {','});
                AssmMark  = aData[0].Trim();
                //TreeNode aNode;
                //aNode = new TreeNode(AssmMark);
            if( sLine.Trim().StartsWith("PART:") ){
                sLine  = sLine.Replace("PART:","");
                string[] pData = sLine.Split(new char[] {','});
                PartMark = pData[0].Trim();
                pNode = new TreeNode(PartMark);

if A vs if A is not None:

if A: will prove false if A is 0, False, empty string, empty list or None, which can lead to undesired results.

Get div tag scroll position using JavaScript

you use the scrollTop attribute

var position = document.getElementById('id').scrollTop;

OpenCV !_src.empty() in function 'cvtColor' error

In my case it was a permission issue. I had to:

  • chmod a+wrx the image,

then it worked.

justify-content property isn't working

I was having a lot of problems with justify-content, and I figured out the problem was "margin: 0 auto"

The auto part overrides the justify-content so its always displayed according to the margin and not to the justify-content.

Google Chrome display JSON AJAX response as tree and not as a plain text

In order for it to display the JSON message properly it has to have the "application/json" mime type and to be correctly structured.

You can check the structure here

Querying a linked sql server

I use open query to perform this task like so:

select top 1 *
from openquery(

The example above uses open query to select data from a database on a linked server into a database of your choosing.

Note: For completeness of reference, you may perform a simple select like so:

select top 1 * from openquery(

java.lang.UnsupportedClassVersionError: Unsupported major.minor version 51.0 (unable to load class frontend.listener.StartupListener)

What is your output when you do java -version? This will tell you what version the running JVM is.

The Unsupported major.minor version 51.0 error could mean:

  • Your server is running a lower Java version then the one used to compile your Servlet and vice versa

Either way, uninstall all JVM runtimes including JDK and download latest and re-install. That should fix any Unsupported major.minor error as you will have the lastest JRE and JDK (Maybe even newer then the one used to compile the Servlet)

See: (7 Update 25 )

and here: (Java Platform (JDK) 7u25)

for the latest version of the JRE and JDK respectively.


Most likely your code was written in Java7 however maybe it was done using Java7update4 and your system is running Java7update3. Thus they both are effectively the same major version but the minor versions differ. Only the larger minor version is backward compatible with the lower minor version.

Edit 2 : If you have more than one jdk installed on your pc. you should check that Apache Tomcat is using the same one (jre) you are compiling your programs with. If you installed a new jdk after installing apache it normally won't select the new version.

Is it better in C++ to pass by value or pass by constant reference?

Edit: New article by Dave Abrahams on cpp-next:

Want speed? Pass by value.

Pass by value for structs where the copying is cheap has the additional advantage that the compiler may assume that the objects don't alias (are not the same objects). Using pass-by-reference the compiler cannot assume that always. Simple example:

foo * f;

void bar(foo g) {
    g.i = 10;
    f->i = 2;
    g.i += 5;

the compiler can optimize it into

g.i = 15;
f->i = 2;

since it knows that f and g doesn't share the same location. if g was a reference (foo &), the compiler couldn't have assumed that. since g.i could then be aliased by f->i and have to have a value of 7. so the compiler would have to re-fetch the new value of g.i from memory.

For more pratical rules, here is a good set of rules found in Move Constructors article (highly recommended reading).

  • If the function intends to change the argument as a side effect, take it by non-const reference.
  • If the function doesn't modify its argument and the argument is of primitive type, take it by value.
  • Otherwise take it by const reference, except in the following cases
    • If the function would then need to make a copy of the const reference anyway, take it by value.

"Primitive" above means basically small data types that are a few bytes long and aren't polymorphic (iterators, function objects, etc...) or expensive to copy. In that paper, there is one other rule. The idea is that sometimes one wants to make a copy (in case the argument can't be modified), and sometimes one doesn't want (in case one wants to use the argument itself in the function if the argument was a temporary anyway, for example). The paper explains in detail how that can be done. In C++1x that technique can be used natively with language support. Until then, i would go with the above rules.

Examples: To make a string uppercase and return the uppercase version, one should always pass by value: One has to take a copy of it anyway (one couldn't change the const reference directly) - so better make it as transparent as possible to the caller and make that copy early so that the caller can optimize as much as possible - as detailed in that paper:

my::string uppercase(my::string s) { /* change s and return it */ }

However, if you don't need to change the parameter anyway, take it by reference to const:

bool all_uppercase(my::string const& s) { 
    /* check to see whether any character is uppercase */

However, if you the purpose of the parameter is to write something into the argument, then pass it by non-const reference

bool try_parse(T text, my::string &out) {
    /* try to parse, write result into out */

Loading a .json file into c# program

I have done it like:

            using (StreamReader sr = File.OpenText(jsonFilePath))
                var myObject = JsonConvert.DeserializeObject<List<YourObject>>(sr.ReadToEnd());

also, you can do this with async call like: sr.ReadToEndAsync(). using Newtonsoft.Json as reference.

Hope, this helps.

Use of min and max functions in C++

fmin and fmax are only for floating point and double variables.

min and max are template functions that allow comparison of any types, given a binary predicate. They can also be used with other algorithms to provide complex functionality.

How do you save/store objects in SharedPreferences on Android?

I know this thread is bit old. But I'm going to post this anyway hoping it might help someone. We can store fields of any Object to shared preference by serializing the object to String. Here I have used GSON for storing any object to shared preference.

Save Object to Preference :

public static void saveObjectToSharedPreference(Context context, String preferenceFileName, String serializedObjectKey, Object object) {
    SharedPreferences sharedPreferences = context.getSharedPreferences(preferenceFileName, 0);
    SharedPreferences.Editor sharedPreferencesEditor = sharedPreferences.edit();
    final Gson gson = new Gson();
    String serializedObject = gson.toJson(object);
    sharedPreferencesEditor.putString(serializedObjectKey, serializedObject);

Retrieve Object from Preference:

public static <GenericClass> GenericClass getSavedObjectFromPreference(Context context, String preferenceFileName, String preferenceKey, Class<GenericClass> classType) {
    SharedPreferences sharedPreferences = context.getSharedPreferences(preferenceFileName, 0);
    if (sharedPreferences.contains(preferenceKey)) {
        final Gson gson = new Gson();
        return gson.fromJson(sharedPreferences.getString(preferenceKey, ""), classType);
    return null;

Note :

Remember to add compile '' to dependencies in your gradle.

Example :

//assume SampleClass exists
SampleClass mObject = new SampleObject();

//to store an object
saveObjectToSharedPreference(context, "mPreference", "mObjectKey", mObject);

//to retrive object stored in preference
mObject = getSavedObjectFromPreference(context, "mPreference", "mObjectKey", SampleClass.class);


As @Sharp_Edge pointed out in comments, the above solution does not work with List.

A slight modification to the signature of getSavedObjectFromPreference() - from Class<GenericClass> classType to Type classType will make this solution generalized. Modified function signature,

public static <GenericClass> GenericClass getSavedObjectFromPreference(Context context, String preferenceFileName, String preferenceKey, Type classType)

For invoking,

getSavedObjectFromPreference(context, "mPreference", "mObjectKey", (Type) SampleClass.class)

Happy Coding!

Axios having CORS issue

I had got the same CORS error while working on a Vue.js project. You can resolve this either by building a proxy server or another way would be to disable the security settings of your browser (eg, CHROME) for accessing cross origin apis (this is temporary solution & not the best way to solve the issue). Both these solutions had worked for me. The later solution does not require any mock server or a proxy server to be build. Both these solutions can be resolved at the front end.

You can disable the chrome security settings for accessing apis out of the origin by typing the below command on the terminal:

/Applications/Google\\ Chrome --user-data-dir="/tmp/chrome_dev_session" --disable-web-security

After running the above command on your terminal, a new chrome window with security settings disabled will open up. Now, run your program (npm run serve / npm run dev) again and this time you will not get any CORS error and would be able to GET request using axios.

Hope this helps!

Error parsing yaml file: mapping values are not allowed here

Or, if spacing is not the problem, it might want the parent directory name rather than the file name.

Not $ dev_appserver
But $ dev_appserver hello/

For example:

Johns-Mac:hello john$
Traceback (most recent call last):
  File "/usr/local/bin/", line 82, in <module>
    _run_file(__file__, globals())
  File "/Applications/", line 212, in _GenerateEventParameters
    raise yaml_errors.EventListenerYAMLError(e)
google.appengine.api.yaml_errors.EventListenerYAMLError: mapping values are not allowed here
  in "", line 3, column 39


Johns-Mac:hello john$ cd ..
Johns-Mac:fbm john$ hello/
INFO     2014-09-15 11:44:27,828] Starting API server at: http://localhost:61049
INFO     2014-09-15 11:44:27,831] Starting module "default" running at: http://localhost:8080

CSS table layout: why does table-row not accept a margin?

See the CSS 2.1 standard, section 17.5.3. When you use display:table-row, the height of the DIV is solely determined by the height of the table-cell elements in it. Thus, margin, padding, and height on those elements have no effect.

$(this).val() not working to get text from span using jquery

-None of the above consistently worked for me. So here is the solution i worked out that works consistently across all browsers as it uses basic functionality. Hope this may help others. Using jQuery 8.2

1) Get the jquery object for "span". 2) Get the DOM object from above. Using jquery .get(0) 3) Using DOM's object's innerText get the text.

Here is a simple example

var curSpan = $(this).parent().children(' span').get(0);
var spansText = curSpan.innerText;


<div >
<input type='checkbox' /><span >testinput</span> 

Ajax success function

The answer given above can't solve my problem.So I change async into false to get the alert message.

            async: false,
            url: myAjax.ajaxurl,
            data: {action: 'submit_data', info: info},
            success: function(data) {
                alert("Data was succesfully captured");

Using psql how do I list extensions installed in a database?

Additionally if you want to know which extensions are available on your server: SELECT * FROM pg_available_extensions

Java: How to resolve java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException

You need to add jaxb dependancies to maven. The glassfish implementation version 2.3.2 is perfectly compatible with new jakarta EE jaxb api version 2.3.2.

<!-- API -->

<!-- Runtime -->

Entity Framework 6 GUID as primary key: Cannot insert the value NULL into column 'Id', table 'FileStore'; column does not allow nulls

You can not. You will / do break a lot of things. Like relationships. WHich rely on the number being pulled back which EF can not do in the way you set it up. THe price for breaking every pattern there is.

Generate the GUID in the C# layer, so that relationships can continue working.

Turning off some legends in a ggplot

You can use guide=FALSE in scale_..._...() to suppress legend.

For your example you should use scale_colour_continuous() because length is continuous variable (not discrete).

(p3 <- ggplot(mov, aes(year, rating, colour = length, shape = mpaa)) +
   scale_colour_continuous(guide = FALSE) +

Or using function guides() you should set FALSE for that element/aesthetic that you don't want to appear as legend, for example, fill, shape, colour.

p0 <- ggplot(mov, aes(year, rating, colour = length, shape = mpaa)) +


Both provided solutions work in new ggplot2 version 2.0.0 but movies dataset is no longer present in this library. Instead you have to use new package ggplot2movies to check those solutions.

mov <- subset(movies, length != "")

Access to the path is denied

  1. Change the setting from built-in account to custom account and enter the other server's username and password.

  2. Keep the setting as integrated (instead of classic mode).

Populate XDocument from String

You can use XDocument.Parse(string) instead of Load(string).

How can I remove all my changes in my SVN working directory?

svn status | grep '^M' | sed -e 's/^.//' | xargs rm

svn update

Will remove any file which has been modified. I seem to remember having trouble with revert when files and directories may have been added.

Running SSH Agent when starting Git Bash on Windows

In a git bash session, you can add a script to ~/.profile or ~/.bashrc (with ~ being usually set to %USERPROFILE%), in order for said session to launch automatically the ssh-agent. If the file doesn't exist, just create it.

This is what GitHub describes in "Working with SSH key passphrases".

The "Auto-launching ssh-agent on Git for Windows" section of that article has a robust script that checks if the agent is running or not. Below is just a snippet, see the GitHub article for the full solution.

# This is just a snippet. See the article above.
if ! agent_is_running; then
elif ! agent_has_keys; then

Other Resources:

"Getting ssh-agent to work with git run from windows command shell" has a similar script, but I'd refer to the GitHub article above primarily, which is more robust and up to date.

Python unexpected EOF while parsing

After the first if statement instead of typing "if" type "elif" and then it should work.


`    while 1:
    date=input("Example: March 21 | What is the date? ")
if date=="June 21":
    sd="23.5° North Latitude
elif date=="March 21" | date=="September 21":
    sd="0° Latitude"
elif date=="December 21":
    sd="23.5° South Latitude"
elif sd:
    print sd `

How do I auto-submit an upload form when a file is selected?

Using jQuery:

$('#file').change(function() {_x000D_
<script src=""></script>_x000D_
<form id="target" action="destination.html">_x000D_
  <input type="file" id="file" value="Go" />_x000D_

How can I write variables inside the tasks file in ansible

Variable definitions are meant to be used in tasks. But if you want to include them in tasks probably use the register directive. Like this:

- name: Define variable in task.
  shell: echo ""
  register: url

- name: Download apache
  shell: wget {{ item }}
  with_items: url.stdout

You can also look at roles as a way of separating tasks depending on the different roles roles. This way you can have separate variables for each of one of your roles. For example you may have a url variable for apache1 and a separate url variable for the role apache2.

What is the cleanest way to get the progress of JQuery ajax request?

jQuery has an AjaxSetup() function that allows you to register global ajax handlers such as beforeSend and complete for all ajax calls as well as allow you to access the xhr object to do the progress that you are looking for

Force Intellij IDEA to reread all maven dependencies

There is also one useful setting that tells IntelliJ to check for new versions of dependencies even if the version numbers didn't change. We had a local maven repository and a snapshot project that was updated a few times but the version numbers stood the same. The problem was that IntelliJ/Maven didn't update this project because of the fixed version number.

To enable checking for a changed dependency although the version number didn't change go to the "Maven Projects" tab, select "Maven settings" and there activate "Always update snapshots".

jquery click event not firing?

Might be useful to some : check for

pointer-events: none;

In the CSS. It prevents clicks from being caught by JS. I think it's relevant because the CSS might be the last place you'd look into in this kind of situation.

Detect if a jQuery UI dialog box is open

If you read the docs.


This method returns a Boolean (true or false), not a jQuery object.

ASP.NET postback with JavaScript

While Phairoh's solution seems theoretically sound, I have also found another solution to this problem. By passing the UpdatePanels id as a paramater (event target) for the doPostBack function the update panel will post back but not the entire page.


*note: second parameter is for addition event args

hope this helps someone!

EDIT: so it seems this same piece of advice was given above as i was typing :)

What are the date formats available in SimpleDateFormat class?

Date and time formats are well described below

SimpleDateFormat (Java Platform SE 7) - Date and Time Patterns

There could be n Number of formats you can possibly make. ex - dd/MM/yyyy or YYYY-'W'ww-u or you can mix and match the letters to achieve your required pattern. Pattern letters are as follow.

  • G - Era designator (AD)
  • y - Year (1996; 96)
  • Y - Week Year (2009; 09)
  • M - Month in year (July; Jul; 07)
  • w - Week in year (27)
  • W - Week in month (2)
  • D - Day in year (189)
  • d - Day in month (10)
  • F - Day of week in month (2)
  • E - Day name in week (Tuesday; Tue)
  • u - Day number of week (1 = Monday, ..., 7 = Sunday)
  • a - AM/PM marker
  • H - Hour in day (0-23)
  • k - Hour in day (1-24)
  • K - Hour in am/pm (0-11)
  • h - Hour in am/pm (1-12)
  • m - Minute in hour (30)
  • s - Second in minute (55)
  • S - Millisecond (978)
  • z - General time zone (Pacific Standard Time; PST; GMT-08:00)
  • Z - RFC 822 time zone (-0800)
  • X - ISO 8601 time zone (-08; -0800; -08:00)

To parse:


Use: new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");

HttpServletRequest to complete URL

I use this method:

public static String getURL(HttpServletRequest req) {

    String scheme = req.getScheme();             // http
    String serverName = req.getServerName();     //
    int serverPort = req.getServerPort();        // 80
    String contextPath = req.getContextPath();   // /mywebapp
    String servletPath = req.getServletPath();   // /servlet/MyServlet
    String pathInfo = req.getPathInfo();         // /a/b;c=123
    String queryString = req.getQueryString();          // d=789

    // Reconstruct original requesting URL
    StringBuilder url = new StringBuilder();

    if (serverPort != 80 && serverPort != 443) {


    if (pathInfo != null) {
    if (queryString != null) {
    return url.toString();

Error: Execution failed for task ':app:clean'. Unable to delete file

react native devs


sudo cd android && ./gradlew clean

and if you want release apk

sudo cd android && ./gradlew assembleRelease

Hope it will help someone

How to get the index with the key in Python dictionary?

#Creating dictionary
animals = {"Cat" : "Pat", "Dog" : "Pat", "Tiger" : "Wild"}

#Convert dictionary to list (array)
keys = list(animals)

#Printing 1st dictionary key by index

#Done :)

Why did I get the compile error "Use of unassigned local variable"?

See this thread concerning uninitialized bools, but it should answer your question.

Local variables are not initialized unless you call their constructors (new) or assign them a value.

What does the return keyword do in a void method in Java?

The keyword simply pops a frame from the call stack returning the control to the line following the function call.

How to install pip with Python 3?

Assuming you are in a highly restricted computer env (such as myself) without root access or ability to install packages...

I had never setup a fresh/standalone/raw/non-root instance of Python+virtualenv before this post. I had do quite a bit of Googling to make this work.

  1. Decide if you are using python (python2) or python3 and set your PATH correctly. (I am strictly a python3 user.) All commands below can substitute python3 for python if you are python2 user.
  2. wget
  3. tar -xzvf virtualenv-x.y.z.tar.gz
  4. python3 virtualenv-x.y.z/ --python $(which python3) /path/to/new/virtualenv
  5. source /path/to/new/virtualenv/bin/activate
    • Assumes you are using a Bourne-compatible shell, e.g., bash
    • Brilliantly, this virtualenv package includes a standalone version of pip and setuptools that are auto-magically installed into each new virtualenv. This solves the chicken and egg problem.
    • You may want to create an alias (or update your ~/.bashrc, etc.) for this final command to activate the python virtualenv during each login. It can be a pain to remember all these paths and commands.
  6. Check your version of python now: which python3 should give: /path/to/new/virtualenv/bin/python3
  7. Check pip is also available in the virtualenv via which pip... should give: /path/to/new/virtualenv/bin/pip

Then... pip, pip, pip!

Final tip to newbie Pythoneers: You don't think you need virtualenv when you start, but you will be happy to have it later. Helps with "what if" installation / upgrade scenarios for open source / shared packages.


Is there a method to generate a UUID with go language

There is an official implementation by Google:

Generating a version 4 UUID works like this:

package main

import (

func main() {
    id := uuid.New()

Try it here:

python location on mac osx

I have a cook recipe for finding things in linux/macos

First update the locate db then do a

locate WHATiWANTtoSEARCH | less

do a /find to find what you are looking for.

to update your locate db in macos do this:

sudo /usr/libexec/locate.updatedb

it sometimes takes a while. Hope this helps :)

Datatable to html Table

The first answer is correct, but if you have a large amount of data (in my project I had 8.000 rows * 8 columns) is tragically slow.... Having a string that becomes that large in c# is why that solution is forbiden

Instead using a large string I used a string array that I join at the end in order to return the string of the html table. Moreover, I used a linq expression ((from o in row.ItemArray select o.ToString()).ToArray()) in order to join each DataRow of the table, instead of looping again, in order to save as much time as possible.

This is my sample code:

private string MakeHtmlTable(DataTable data)
            string[] table = new string[data.Rows.Count] ;
            long counter = 1;
            foreach (DataRow row in data.Rows)
                table[counter-1] = "<tr><td>" + String.Join("</td><td>", (from o in row.ItemArray select o.ToString()).ToArray()) + "</td></tr>";


            return "</br><table>" + String.Join("", table) + "</table>";

How to use sys.exit() in Python

I think you can use


You may check it here in the python 2.7 doc:

The optional argument arg can be an integer giving the exit status (defaulting to zero), or another type of object. If it is an integer, zero is considered “successful termination” and any nonzero value is considered “abnormal termination” by shells and the like.

Easy way of running the same junit test over and over?

With IntelliJ, you can do this from the test configuration. Once you open this window, you can choose to run the test any number of times you want,.

enter image description here

when you run the test, intellij will execute all tests you have selected for the number of times you specified.

Example running 624 tests 10 times: enter image description here

How do I tell Gradle to use specific JDK version?

As seen in Gradle (Eclipse plugin)

Gradle uses whichever JDK it finds in your path (to check, use java -version). Alternatively, you can set the JAVA_HOME environment variable to point to the install directory of the desired JDK.

If you are using this Eclipse plugin or Enide Studio 2014, alternative JAVA_HOME to use (set in Preferences) will be in version 0.15, see

Can curl make a connection to any TCP ports, not just HTTP/HTTPS?

Of course:


Port 80 and 443 are just default port numbers.

Download pdf file using jquery ajax

jQuery has some issues loading binary data using AJAX requests, as it does not yet implement some HTML5 XHR v2 capabilities, see this enhancement request and this discussion

Given that, you have one of two solutions:

First solution, abandon JQuery and use XMLHTTPRequest

Go with the native HTMLHTTPRequest, here is the code to do what you need

  var req = new XMLHttpRequest();"GET", "/file.pdf", true);
  req.responseType = "blob";

  req.onload = function (event) {
    var blob = req.response;
    var link=document.createElement('a');
    link.href=window.URL.createObjectURL(blob);"Dossier_" + new Date() + ".pdf";;


Second solution, use the jquery-ajax-native plugin

The plugin can be found here and can be used to the XHR V2 capabilities missing in JQuery, here is a sample code how to use it

  dataType: 'native',
  url: "/file.pdf",
  xhrFields: {
    responseType: 'blob'
  success: function(blob){
      var link=document.createElement('a');
      link.href=window.URL.createObjectURL(blob);"Dossier_" + new Date() + ".pdf";;

Copy from one workbook and paste into another

This should do it, let me know if you have trouble with it:

Sub foo()
Dim x As Workbook
Dim y As Workbook

'## Open both workbooks first:
Set x = Workbooks.Open(" path to copying book ")
Set y = Workbooks.Open(" path to destination book ")

'Now, copy what you want from x:
x.Sheets("name of copying sheet").Range("A1").Copy

'Now, paste to y worksheet:

'Close x:

End Sub

Alternatively, you could just:

Sub foo2()
Dim x As Workbook
Dim y As Workbook

'## Open both workbooks first:
Set x = Workbooks.Open(" path to copying book ")
Set y = Workbooks.Open(" path to destination book ")

'Now, transfer values from x to y:
y.Sheets("sheetname").Range("A1").Value = x.Sheets("name of copying sheet").Range("A1") 

'Close x:

End Sub

To extend this to the entire sheet:

With x.Sheets("name of copying sheet").UsedRange
    'Now, paste to y worksheet:
    y.Sheets("sheet name").Range("A1").Resize( _
        .Rows.Count, .Columns.Count) = .Value
End With

And yet another way, store the value as a variable and write the variable to the destination:

Sub foo3()
Dim x As Workbook
Dim y As Workbook
Dim vals as Variant

'## Open both workbooks first:
Set x = Workbooks.Open(" path to copying book ")
Set y = Workbooks.Open(" path to destination book ")

'Store the value in a variable:
vals = x.Sheets("name of sheet").Range("A1").Value

'Use the variable to assign a value to the other file/sheet:
y.Sheets("sheetname").Range("A1").Value = vals 

'Close x:

End Sub

The last method above is usually the fastest for most applications, but do note that for very large datasets (100k rows) it's observed that the Clipboard actually outperforms the array dump:

Copy/PasteSpecial vs Range.Value = Range.Value

That said, there are other considerations than just speed, and it may be the case that the performance hit on a large dataset is worth the tradeoff, to avoid interacting with the Clipboard.

Can I get JSON to load into an OrderedDict?

Simple version for Python 2.7+

my_ordered_dict = json.loads(json_str, object_pairs_hook=collections.OrderedDict)

Or for Python 2.4 to 2.6

import simplejson as json
import ordereddict

my_ordered_dict = json.loads(json_str, object_pairs_hook=ordereddict.OrderedDict)

Python: BeautifulSoup - get an attribute value based on the name attribute

theharshest answered the question but here is another way to do the same thing. Also, In your example you have NAME in caps and in your code you have name in lowercase.

s = '<div class="question" id="get attrs" name="python" x="something">Hello World</div>'
soup = BeautifulSoup(s)

attributes_dictionary = soup.find('div').attrs
print attributes_dictionary
# prints: {'id': 'get attrs', 'x': 'something', 'class': ['question'], 'name': 'python'}

print attributes_dictionary['class'][0]
# prints: question

print soup.find('div').get_text()
# prints: Hello World

How do files get into the External Dependencies in Visual Studio C++?

The External Dependencies folder is populated by IntelliSense: the contents of the folder do not affect the build at all (you can in fact disable the folder in the UI).

You need to actually include the header (using a #include directive) to use it. Depending on what that header is, you may also need to add its containing folder to the "Additional Include Directories" property and you may need to add additional libraries and library folders to the linker options; you can set all of these in the project properties (right click the project, select Properties). You should compare the properties with those of the project that does build to determine what you need to add.

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

Check example link below and click on the div to get the color value in hex.

var color = '';_x000D_
$('div').click(function() {_x000D_
  var x = $(this).css('backgroundColor');_x000D_
function hexc(colorval) {_x000D_
  var parts = colorval.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);_x000D_
  for (var i = 1; i <= 3; ++i) {_x000D_
    parts[i] = parseInt(parts[i]).toString(16);_x000D_
    if (parts[i].length == 1) parts[i] = '0' + parts[i];_x000D_
  color = '#' + parts.join('');_x000D_
<script src=""></script>_x000D_
<div class='div' style='background-color: #f5b405'>Click me!</div>

Check working example at

Check if item is in an array / list

You have to use .values for arrays. for example say you have dataframe which has a column name ie, test['Name'], you can do

if name in test['Name'].values :

for a normal list you dont have to use .values

Difference between Visibility.Collapsed and Visibility.Hidden

The difference is that Visibility.Hidden hides the control, but reserves the space it occupies in the layout. So it renders whitespace instead of the control. Visibilty.Collapsed does not render the control and does not reserve the whitespace. The space the control would take is 'collapsed', hence the name.

The exact text from the MSDN:

Collapsed: Do not display the element, and do not reserve space for it in layout.

Hidden: Do not display the element, but reserve space for the element in layout.

Visible: Display the element.


Android ADB stop application command like "force-stop" for non rooted device

If you want to kill the Sticky Service,the following command NOT WORKING:

adb shell am force-stop <PACKAGE>
adb shell kill <PID>

The following command is WORKING:

adb shell pm disable <PACKAGE>

If you want to restart the app,you must run command below first:

adb shell pm enable <PACKAGE>

Is Django for the frontend or backend?


Django is a framework, not a language. Python is the language in which Django is written.

Django is a collection of Python libs allowing you to quickly and efficiently create a quality Web application, and is suitable for both frontend and backend.

However, Django is pretty famous for its "Django admin", an auto generated backend that allows you to manage your website in a blink for a lot of simple use cases without having to code much.

More precisely, for the front end, Django helps you with data selection, formatting, and display. It features URL management, a templating language, authentication mechanisms, cache hooks, and various navigation tools such as paginators.

For the backend, Django comes with an ORM that lets you manipulate your data source with ease, forms (an HTML independent implementation) to process user input and validate data and signals, and an implementation of the observer pattern. Plus a tons of use-case specific nifty little tools.

For the rest of the backend work Django doesn't help with, you just use regular Python. Business logic is a pretty broad term.

You probably want to know as well that Django comes with the concept of apps, a self contained pluggable Django library that solves a problem. The Django community is huge, and so there are numerous apps that do specific business logic that vanilla Django doesn't.

Drop all duplicate rows across multiple columns in Python Pandas

This is much easier in pandas now with drop_duplicates and the keep parameter.

import pandas as pd
df = pd.DataFrame({"A":["foo", "foo", "foo", "bar"], "B":[0,1,1,1], "C":["A","A","B","A"]})
df.drop_duplicates(subset=['A', 'C'], keep=False)

Link to a section of a webpage

Hashtags at the end of the URL bring a visitor to the element with the ID: e.g. 

Would bring you to where the DIV with the ID 'answers' begins. Also, you can use the name attribute in anchor tags, to create the same effect.


MySQL select where column is not empty

Compare value of phone2 with empty string:

select phone, phone2 
from jewishyellow.users 
where phone like '813%' and phone2<>''

Note that NULL value is interpreted as false.

How to set the background image of a html 5 canvas to .png image

You can give the background image in css :

#canvas { background:url(example.jpg) }

it will show you canvas back ground image

vertical-align with Bootstrap 3

Update 2020

I know the original question was for Bootstrap 3, but now that Bootstrap 4 has been released, here is some updated guidance on vertical center.

Important! Vertical center is relative to the height of the parent

If the parent of the element your trying to center has no defined height, none of the vertical centering solutions will work!

Bootstrap 4

Now that Bootstrap 4 is flexbox by default there are many different approaches to vertical alignment using: auto-margins, flexbox utils, or the display utils along with vertical align utils. At first "vertical align utils" seems obvious, but these only work with inline and table display elements. Here are some Bootstrap 4 vertical centering options..

1 - Vertical Center Using Auto Margins:

Another way to vertically center is to use my-auto. This will center the element within its container. For example, h-100 makes the row full height, and my-auto will vertically center the col-sm-12 column.

<div class="row h-100">
    <div class="col-sm-12 my-auto">
        <div class="card card-block w-25">Card</div>

Bootstrap 4 - Vertical center using auto-margins Demo

my-auto represents margins on the vertical y-axis and is equivalent to:

margin-top: auto;
margin-bottom: auto;

2 - Vertical Center with Flexbox:

Vertical center grid columns

Since Bootstrap 4 .row is now display:flex you can simply use align-self-center on any column to vertically center it...

       <div class="row">
           <div class="col-6 align-self-center">
                <div class="card card-block">
           <div class="col-6">
                <div class="card card-inverse card-danger">

or, use align-items-center on the entire .row to vertically center align all col-* in the row...

       <div class="row align-items-center">
           <div class="col-6">
                <div class="card card-block">
           <div class="col-6">
                <div class="card card-inverse card-danger">

Bootstrap 4 - Vertical center different height columns Demo

3 - Vertical Center Using Display Utils:

Bootstrap 4 has display utils that can be used for display:table, display:table-cell, display:inline, etc.. These can be used with the vertical alignment utils to align inline, inline-block or table cell elements.

<div class="row h-50">
    <div class="col-sm-12 h-100 d-table">
        <div class="card card-block d-table-cell align-middle">
            I am centered vertically

Bootstrap 4 - Vertical center using display utils Demo

Also see: Vertical Align Center in Bootstrap 4

Bootstrap 3

Flexbox method on the container of the item(s) to center:

.display-flex-center {
    display: flex;
    align-items: center;

Transform translateY method:

.transform-center-parent {
    position: relative;
    transform-style: preserve-3d;

.transform-center {
    position: relative;
    top: 50%;
    transform: translateY(-50%);

Display inline method:

.display-inline-block {
    display: inline;
.display-inline-block > div {
    display: inline-block;
    float: none;
    vertical-align: middle;

Demo of Bootstrap 3 centering methods

ImportError: No module named scipy

This may be too basic (and perhaps assumable), but -

Fedora users can use:

sudo dnf install python-scipy

and then (For python3.x):

pip3 install scipy

or (For python2.7):

pip2 install scipy

Parse string to date with moment.js

  • How to change any string date to object date (also with moment.js):

let startDate = "2019-01-16T20:00:00.000"; let endDate = "2019-02-11T20:00:00.000"; let sDate = new Date(startDate); let eDate = new Date(endDate);

  • with moment.js:

startDate = moment(sDate); endDate = moment(eDate);

Declaring abstract method in TypeScript

The name property is marked as protected. This was added in TypeScript 1.3 and is now firmly established.

The makeSound method is marked as abstract, as is the class. You cannot directly instantiate an Animal now, because it is abstract. This is part of TypeScript 1.6, which is now officially live.

abstract class Animal {
    constructor(protected name: string) { }

    abstract makeSound(input : string) : string;

    move(meters) {
        alert( + " moved " + meters + "m.");

class Snake extends Animal {
    constructor(name: string) { super(name); }

    makeSound(input : string) : string {
        return "sssss"+input;

    move() {

The old way of mimicking an abstract method was to throw an error if anyone used it. You shouldn't need to do this any more once TypeScript 1.6 lands in your project:

class Animal {
    constructor(public name) { }
    makeSound(input : string) : string {
        throw new Error('This method is abstract');
    move(meters) {
        alert( + " moved " + meters + "m.");

class Snake extends Animal {
    constructor(name) { super(name); }
    makeSound(input : string) : string {
        return "sssss"+input;
    move() {

Getting a Request.Headers value

The following code should allow you to check for the existance of the header you're after in Request.Headers:

if (Request.Headers.AllKeys.Contains("XYZComponent"))
    // Can now check if the value is true:
    var value = Convert.ToBoolean(Request.Headers["XYZComponent"]);

How to draw a rounded Rectangle on HTML Canvas?

To make the function more consistent with the normal means of using a canvas context, the canvas context class can be extended to include a 'fillRoundedRect' method -- that can be called in the same way fillRect is called:

var canv = document.createElement("canvas");
var cctx = canv.getContext("2d");

// If thie canvasContext class doesn't have  a fillRoundedRect, extend it now
if (!cctx.constructor.prototype.fillRoundedRect) {
  // Extend the canvaseContext class with a fillRoundedRect method
  cctx.constructor.prototype.fillRoundedRect = 
    function (xx,yy, ww,hh, rad, fill, stroke) {
      if (typeof(rad) == "undefined") rad = 5;
      this.moveTo(xx+rad, yy);
      this.arcTo(xx+ww, yy,    xx+ww, yy+hh, rad);
      this.arcTo(xx+ww, yy+hh, xx,    yy+hh, rad);
      this.arcTo(xx,    yy+hh, xx,    yy,    rad);
      this.arcTo(xx,    yy,    xx+ww, yy,    rad);
      if (stroke) this.stroke();  // Default to no stroke
      if (fill || typeof(fill)=="undefined") this.fill();  // Default to fill
  }; // end of fillRoundedRect method

The code checks to see if the prototype for the constructor for the canvas context object contains a 'fillRoundedRect' property and adds one -- the first time around. It is invoked in the same manner as the fillRect method:

  ctx.fillStyle = "#eef";  ctx.strokeStyle = "#ddf";
  // ctx.fillRect(10,10, 200,100);
  ctx.fillRoundedRect(10,10, 200,100, 5);

The method uses the arcTo method as Grumdring did. In the method, this is a reference to the ctx object. The stroke argument defaults to false if undefined. The fill argument defaults to fill the rectangle if undefined.

(Tested on Firefox, I don't know if all implementations permit extension in this manner.)

How can I create a small color box using html and css?

You can create these easily using the floating ability of CSS, for example. I have created a small example on Jsfiddle over here, all the related css and html is also provided there.

.foo {_x000D_
  float: left;_x000D_
  width: 20px;_x000D_
  height: 20px;_x000D_
  margin: 5px;_x000D_
  border: 1px solid rgba(0, 0, 0, .2);_x000D_
.blue {_x000D_
  background: #13b4ff;_x000D_
.purple {_x000D_
  background: #ab3fdd;_x000D_
.wine {_x000D_
  background: #ae163e;_x000D_
<div class="foo blue"></div>_x000D_
<div class="foo purple"></div>_x000D_
<div class="foo wine"></div>

phpinfo() - is there an easy way for seeing it?

From the CLI:

php -r 'phpinfo();'

Why does the order in which libraries are linked sometimes cause errors in GCC?

You may can use -Xlinker option.

g++ -o foobar  -Xlinker -start-group  -Xlinker libA.a -Xlinker libB.a -Xlinker libC.a  -Xlinker -end-group 

is ALMOST equal to

g++ -o foobar  -Xlinker -start-group  -Xlinker libC.a -Xlinker libB.a -Xlinker libA.a  -Xlinker -end-group 

Careful !

  1. The order within a group is important ! Here's an example: a debug library has a debug routine, but the non-debug library has a weak version of the same. You must put the debug library FIRST in the group or you will resolve to the non-debug version.
  2. You need to precede each library in the group list with -Xlinker

Git pull - Please move or remove them before you can merge

If you are getting error like

  • branch master -> FETCH_HEAD error: The following untracked working tree files would be overwritten by merge: src/dj/abc.html Please move or remove them before you merge. Aborting

Try removing the above file manually(Careful). Git will merge this file from master branch.

How to label scatterplot points by name?

Well I did not think this was possible until I went and checked. In some previous version of Excel I could not do this. I am currently using Excel 2013.

This is what you want to do in a scatter plot:

  1. right click on your data point

  2. select "Format Data Labels" (note you may have to add data labels first)

  3. put a check mark in "Values from Cells"
  4. click on "select range" and select your range of labels you want on the points

Example Graph

UPDATE: Colouring Individual Labels

In order to colour the labels individually use the following steps:

  1. select a label. When you first select, all labels for the series should get a box around them like the graph above.
  2. Select the individual label you are interested in editing. Only the label you have selected should have a box around it like the graph below.
  3. On the right hand side, as shown below, Select "TEXT OPTIONS".
  4. Expand the "TEXT FILL" category if required.
  5. Second from the bottom of the category list is "COLOR", select the colour you want from the pallet.

If you have the entire series selected instead of the individual label, text formatting changes should apply to all labels instead of just one.


How to Correctly Check if a Process is running and Stop it

Thanks @Joey. It's what I am looking for.

I just bring some improvements:

  • to take into account multiple processes
  • to avoid reaching the timeout when all processes have terminated
  • to package the whole in a function

function Stop-Processes {
        [parameter(Mandatory=$true)] $processName,
                                     $timeout = 5
    $processList = Get-Process $processName -ErrorAction SilentlyContinue
    if ($processList) {
        # Try gracefully first
        $processList.CloseMainWindow() | Out-Null

        # Wait until all processes have terminated or until timeout
        for ($i = 0 ; $i -le $timeout; $i ++){
            $AllHaveExited = $True
            $processList | % {
                $process = $_
                If (!$process.HasExited){
                    $AllHaveExited = $False
            If ($AllHaveExited){
            sleep 1
        # Else: kill
        $processList | Stop-Process -Force        

Using PHP variables inside HTML tags?

HI Jasper,

you can do this:

sprintf("<a href=\"\">Click Here</a>", $param);

Already defined in .obj - no double inclusions

This is not a compiler error: the error is coming from the linker. After compilation, the linker will merge the object files resulting from the compilation of each of your translation units (.cpp files).

The linker finds out that you have the same symbol defined multiple times in different translation units, and complains about it (it is a violation of the One Definition Rule).

The reason is most certainly that main.cpp includes client.cpp, and both these files are individually processed by the compiler to produce two separate object files. Therefore, all the symbols defined in the client.cpp translation unit will be defined also in the main.cpp translation unit. This is one of the reasons why you do not usually #include .cpp files.

Put the definition of your class in a separate client.hpp file which does not contain also the definitions of the member functions of that class; then, let client.cpp and main.cpp include that file (I mean #include). Finally, leave in client.cpp the definitions of your class's member functions.


#include <boost/asio.hpp>

class SocketClient // Or whatever the name is...

// ...

    bool read(int, char*); // Or whatever the name is...

//  ...



#include "Client.h"

// ...

bool SocketClient::read(int, char*)
    // Implementation  goes here...

// ... (add the definitions for all other member functions)


#include <iostream>
#include <string>
#include <sstream>
#include <boost/asio.hpp>
#include <boost/thread/thread.hpp>
#include "client.h"
//              ^^ Notice this!


#include "main.h"

How to check for the type of a template parameter?

I think todays, it is better to use, but only with C++17.

#include <type_traits>

template <typename T>
void foo() {
    if constexpr (std::is_same_v<T, animal>) {
        // use type specific operations... 

If you use some type specific operations in if expression body without constexpr, this code will not compile.

How do I install command line MySQL client on mac?

The mysql client is available in macOS ports. If you don't have this excellent third party package manager already installed, it is available from here:

Once you have installed macports, open a terminal and make sure everything is up to date:

sudo port selfupdate

There are multiple different versions of MySQL and mariadb (community fork of MySQL) available in the ports repos. List available versions using the following command:

port search 'mariadb*'

I recommend choosing mariadb over mysql as it is, mostly, a drop in replacement ( and has excellent community support.

If applicable, choose which version of mariadb you want (a list of versions of mariadb is available here: If you're not bothered, install the default version:

sudo port install mariadb

Mariadb (including the mysql-compatible command line client) is now available on your system. On my system, the CLI client resides in the following location:

$ /opt/local/bin/mysql --version
/opt/local/bin/mysql  Ver 15.1 Distrib 5.5.68-MariaDB, for osx10.15 (x86_64) using readline 5.1

It's obviously a bit inconvenient to type out the full path, /opt/local/bin/mysql each time you want to use the client. Ports has already thought of this problem. To view available versions of mysql on your system, run:

$ port select mysql

Available versions for mysql:
mariadb (active)

Choose one from the list. For example, to use mariadb as the default mysql client:

sudo port select mysql mariadb

Now open a fresh terminal window and you should be able to start the mariadb mysql CLI client:

mysql -h <hostname> -u <username> -p

Hashset vs Treeset

If you aren't inserting enough elements to result in frequent rehashings (or collisions, if your HashSet can't resize), a HashSet certainly gives you the benefit of constant time access. But on sets with lots of growth or shrinkage, you may actually get better performance with Treesets, depending on the implementation.

Amortized time can be close to O(1) with a functional red-black tree, if memory serves me. Okasaki's book would have a better explanation than I can pull off. (Or see his publication list)

Where is svn.exe in my machine?

Download it from here:

and run the setup program. The executables are in:

\Program Files (x86)\Subversion\bin

for the default installation.

Any way to Invoke a private method?

If the method accepts non-primitive data type then the following method can be used to invoke a private method of any class:

public static Object genericInvokeMethod(Object obj, String methodName,
            Object... params) {
        int paramCount = params.length;
        Method method;
        Object requiredObj = null;
        Class<?>[] classArray = new Class<?>[paramCount];
        for (int i = 0; i < paramCount; i++) {
            classArray[i] = params[i].getClass();
        try {
            method = obj.getClass().getDeclaredMethod(methodName, classArray);
            requiredObj = method.invoke(obj, params);
        } catch (NoSuchMethodException e) {
        } catch (IllegalArgumentException e) {
        } catch (IllegalAccessException e) {
        } catch (InvocationTargetException e) {

        return requiredObj;

The Parameter accepted are obj, methodName and the parameters. For example

public class Test {
private String concatString(String a, String b) {
    return (a+b);

Method concatString can be invoked as

Test t = new Test();
    String str = (String) genericInvokeMethod(t, "concatString", "Hello", "Mr.x");

Jenkins - How to access BUILD_NUMBER environment variable

Assuming I am understanding your question and setup correctly,

If you're trying to use the build number in your script, you have two options:

1) When calling ant, use: ant -Dbuild_parameter=${BUILD_NUMBER}

2) Change your script so that:

<property environment="env" />
<property name="build_parameter"  value="${env.BUILD_NUMBER}"/>

Adding days to $Date in PHP

All you have to do is use days instead of day like this:

$Date = "2010-09-17";
echo date('Y-m-d', strtotime($Date. ' + 1 days'));
echo date('Y-m-d', strtotime($Date. ' + 2 days'));

And it outputs correctly:


Prevent Bootstrap Modal from disappearing when clicking outside or pressing escape?

Just add data-backdrop="static" and data-keyboard="false" attributes to that modal.


<a data-controls-modal="your_div_id" data-backdrop="static" data-keyboard="false" href="#">

Signed versus Unsigned Integers

I'll go into differences at the hardware level, on x86. This is mostly irrelevant unless you're writing a compiler or using assembly language. But it's nice to know.

Firstly, x86 has native support for the two's complement representation of signed numbers. You can use other representations but this would require more instructions and generally be a waste of processor time.

What do I mean by "native support"? Basically I mean that there are a set of instructions you use for unsigned numbers and another set that you use for signed numbers. Unsigned numbers can sit in the same registers as signed numbers, and indeed you can mix signed and unsigned instructions without worrying the processor. It's up to the compiler (or assembly programmer) to keep track of whether a number is signed or not, and use the appropriate instructions.

Firstly, two's complement numbers have the property that addition and subtraction is just the same as for unsigned numbers. It makes no difference whether the numbers are positive or negative. (So you just go ahead and ADD and SUB your numbers without a worry.)

The differences start to show when it comes to comparisons. x86 has a simple way of differentiating them: above/below indicates an unsigned comparison and greater/less than indicates a signed comparison. (E.g. JAE means "Jump if above or equal" and is unsigned.)

There are also two sets of multiplication and division instructions to deal with signed and unsigned integers.

Lastly: if you want to check for, say, overflow, you would do it differently for signed and for unsigned numbers.

Long vs Integer, long vs int, what to use and when?

There are a couple of things you can't do with a primitive type:

  • Have a null value
  • synchronize on them
  • Use them as type parameter for a generic class, and related to that:
  • Pass them to an API that works with Objects

Unless you need any of those, you should prefer primitive types, since they require less memory.

JAVA_HOME does not point to the JDK

This is by design. You cannot use ant's java.home (which is a java.lang.System property) interchangeably with how JAVA_HOME is set in the OS environment. You are probably trying to assert the location of the Java compiler with a fundamentally different value from a different property layer -- i.e. java.home (from Ant's Java internals) points to the Java Runtime Environment at <any_installed_java_pointed_to_by_ant>/jre while JDK_HOME (from the OS environment) is usually set to <DOWNLOADED_AND_INSTALLED_JAVA_DEVELOPMENT_KIT>.

See my question and answer here for more details: Where does Ant set its 'java.home' (and is it wrong) and is it supposed to append '/jre'?

The solution is to access the system environment property within Ant by using ${env.JAVA_HOME}. Specify which java to use explicitly in the Javac Task by setting the executable property to the javac path and the fork property to yes (see Ant's Javac Task Documentation). That way, it doesn't matter what Java environment Ant is running inside, the compiler is always clearly specified!

How can I read and parse CSV files in C++?

A minor edition to @sastanin's solution, so that it can deal with newlines within quotes.

std::vector<std::vector<std::string>> readCSV(std::istream &in) {
    std::vector<std::vector<std::string>> table;

    while (!in.eof()) {
        CSVState state = CSVState::UnquotedField;
        std::vector<std::string> fields {""};
        size_t i = 0; // index of the current field
        for (char c : row) {
            switch (state) {
                case CSVState::UnquotedField:
                    switch (c) {
                        case ',': // end of field
                                  fields.push_back(""); i++;
                        case '"': state = CSVState::QuotedField;
                        default:  fields[i].push_back(c);
                                  break; }
                case CSVState::QuotedField:
                    switch (c) {
                        case '"': state = CSVState::QuotedQuote;
                        default:  fields[i].push_back(c);
                                  break; }
                case CSVState::QuotedQuote:
                    switch (c) {
                        case ',': // , after closing quote
                                  fields.push_back(""); i++;
                                  state = CSVState::UnquotedField;
                        case '"': // "" -> "
                                  state = CSVState::QuotedField;
                        case '\n': // newline
                                  state = CSVState::UnquotedField;
                                  fields = vector<string>{""};
                                  i = 0;
                        default:  // end of quote
                                  state = CSVState::UnquotedField;
                                  break; }
    return table;

How to stop an unstoppable zombie job on Jenkins without restarting the server?

I use the Monitoring Plugin for this task. After the installation of the plugin

  1. Go to Manage Jenkins > Monitoring of Hudson/Jenkins master
  2. Expand the Details of Threads, the small blue link on the right side
  3. Search for the Job Name that is hung

    The Thread's name will start like this

    Executor #2 for master : executing <your-job-name> #<build-number>

  4. Click the red, round button on the very right in the table of the line your desired job has

How to Enable ActiveX in Chrome?

Google Chrome comes with an ActiveX shim, as part of its default plugin array. So Google Chrome features at least partial support for ActiveX controls (as do many non-Internet Explorer browsers). I can't find information as to whether or not this includes support for ActiveX security certificates or the like, nor if/where such plugins can be controlled, within the browser.

..... Note that to enable the plug-in you must run Chrome with the following switch " --allow-all-activex" So in shortcut that is used to start up Chrome, add this after "Chrome.exe"

Latex - Change margins of only a few pages

A slight modification of this to change the \voffset works for me:


And then put your figures in a \begin{changemargin}{-1cm}...\end{changemargin} environment.

selenium get current url after loading a page

Page 2 is in a new tab/window ? If it's this, use the code bellow :

try {

    String winHandleBefore = driver.getWindowHandle();

    for(String winHandle : driver.getWindowHandles()){
        String act = driver.getCurrentUrl();
    }catch(Exception e){

Select all DIV text with single mouse click

I found it useful to wrap this function as a jQuery plugin:

$.fn.selectText = function () {
    return $(this).each(function (index, el) {
        if (document.selection) {
            var range = document.body.createTextRange();
        } else if (window.getSelection) {
            var range = document.createRange();

So, it becomes a reusable solution. Then you can do this:

<div onclick="$(this).selectText()"></div>

And it will selected test in the div.

SQL Server Error : String or binary data would be truncated

this type of error generally occurs when you have to put characters or values more than that you have specified in Database table like in this case: you specify transaction_status varchar(10) but you actually trying to store
_transaction_status which contain 19 characters. that's why you faced this type of error in this code..

Difference between getContext() , getApplicationContext() , getBaseContext() and "this"

The question "what the Context is" is one of the most difficult questions in the Android universe.

Context defines methods that access system resources, retrieve application's static assets, check permissions, perform UI manipulations and many more. In essence, Context is an example of God Object anti-pattern in production.

When it comes to which kind of Context should we use, it becomes very complicated because except for being God Object, the hierarchy tree of Context subclasses violates Liskov Substitution Principle brutally.

This blog post (now from Wayback Machine) attempts to summarize Context classes applicability in different situations.

Let me copy the main table from that post for completeness:

|                            | Application | Activity | Service | ContentProvider | BroadcastReceiver |
| Show a Dialog              | NO          | YES      | NO      | NO              | NO                |
| Start an Activity          | NO¹         | YES      | NO¹     | NO¹             | NO¹               |
| Layout Inflation           | NO²         | YES      | NO²     | NO²             | NO²               |
| Start a Service            | YES         | YES      | YES     | YES             | YES               |
| Bind to a Service          | YES         | YES      | YES     | YES             | NO                |
| Send a Broadcast           | YES         | YES      | YES     | YES             | YES               |
| Register BroadcastReceiver | YES         | YES      | YES     | YES             | NO³               |
| Load Resource Values       | YES         | YES      | YES     | YES             | YES               |
  1. An application CAN start an Activity from here, but it requires that a new task be created. This may fit specific use cases, but can create non-standard back stack behaviors in your application and is generally not recommended or considered good practice.
  2. This is legal, but inflation will be done with the default theme for the system on which you are running, not what’s defined in your application.
  3. Allowed if the receiver is null, which is used for obtaining the current value of a sticky broadcast, on Android 4.2 and above.


Eclipse: How do you change the highlight color of the currently selected method/expression?

If you're using eclipse with PHP package and want to change highlighted colour then there is slight difference to above answer.

  1. Right click on highlighted word
  2. Select 'Preferences'
  3. Go to General > Editors > Text Editors > Annotations. Now look for "PHP elements 'read' occurrences" and "PHP elements 'write' occurrences". You can select your desired colour there.

Change Highlighted text colour in Eclips with PHP

Count occurrences of a char in a string using Bash

awk works well if you your server has it

num=$(echo "${var}" | awk -F, '{print NF-1}')
echo "${num}"

How to use ConfigurationManager

Okay, it took me a while to see this, but there's no way this compiles:

return String.(ConfigurationManager.AppSettings[paramName]);

You're not even calling a method on the String type. Just do this:

return ConfigurationManager.AppSettings[paramName];

The AppSettings KeyValuePair already returns a string. If the name doesn't exist, it will return null.

Based on your edit you have not yet added a Reference to the System.Configuration assembly for the project you're working in.

Android update activity UI from service

Clyde's solution works, but it is a broadcast, which I am pretty sure will be less efficient than calling a method directly. I could be mistaken, but I think the broadcasts are meant more for inter-application communication.

I'm assuming you already know how to bind a service with an Activity. I do something sort of like the code below to handle this kind of problem:

class MyService extends Service {
    MyFragment mMyFragment = null;
    MyFragment mMyOtherFragment = null;

    private void networkLoop() {

        //received new data for list.
        if(myFragment != null)


        //received new data for textView
        if(myFragment !=null)


        //received new data for textView
        if(myOtherFragment !=null)


class MyFragment extends Fragment {

    public void onResume() {
        //Assuming your activity bound to your service

    public void onPause() {
        //Assuming your activity bound to your service

    public void updateList() {
        runOnUiThread(new Runnable() {
            public void run() {
                //Update the list.

    public void updateText() {
       //as above

class MyOtherFragment extends Fragment {
             public void onResume() {
        //Assuming your activity bound to your service

    public void onPause() {
        //Assuming your activity bound to your service

    public void updateSomething() {//etc... }

I left out bits for thread safety, which is essential. Make sure to use locks or something like that when checking and using or changing the fragment references on the service.

GIT clone repo across local file system in windows

After clone, for me push wasn't working.

Solution: Where repo is cloned open .git folder and config file.

For remote origin url set value:

[remote "origin"]
    url = file:///C:/Documentation/git_server/kurmisoftware

Setting Access-Control-Allow-Origin in ASP.Net MVC - simplest possible method

Sometimes OPTIONS verb as well causes problems

Simply: Update your web.config with the following

          <add name="Access-Control-Allow-Origin" value="*" />
          <add name="Access-Control-Allow-Headers" value="Origin, X-Requested-With, Content-Type, Accept" />

And update the webservice/controller headers with httpGet and httpOptions

// GET api/Master/Sync/?version=12121
        public dynamic Sync(string version) 

PHP7 : install ext-dom issue

First of all, read the warning! It says do not run composer as root! Secondly, you're probably using Xammp on your local which has the required php libraries as default.

But in your server you're missing ext-dom. php-xml has all the related packages you need. So, you can simply install it by running:

sudo apt-get update
sudo apt install php-xml

Most likely you are missing mbstring too. If you get the error, install this package as well with:

sudo apt-get install php-mbstring

Then run:

composer update
composer require cviebrock/eloquent-sluggable

Java 8: Difference between two LocalDateTime in multiple units


Duration duration = Duration.between(start, end);
duration = duration.minusDays(duration.toDaysPart()); // essentially "duration (mod 1 day)"
Period period = Period.between(start.toLocalDate(), end.toLocalDate());

and then use the methods period.getYears(), period.getMonths(), period.getDays(), duration.toHoursPart(), duration.toMinutesPart(), duration.toSecondsPart().

Expanded answer

I'll answer the original question, i.e. how to get the time difference between two LocalDateTimes in years, months, days, hours & minutes, such that the "sum" (see note below) of all the values for the different units equals the total temporal difference, and such that the value in each unit is smaller than the next bigger unit—i.e. minutes < 60, hours < 24, and so on.

Given two LocalDateTimes start and end, e.g.

LocalDateTime start = LocalDateTime.of(2019, 11, 29, 17, 15);
LocalDateTime end = LocalDateTime.of(2020, 11, 30, 18, 44);

we can represent the absolute timespan between the two with a Duration—perhaps using Duration.between(start, end). But the biggest unit we can extract out of a Duration is days (as a temporal unit equivalent to 24h)—see the note below for an explanation. To use larger units (months, years) we can represent this Duration with a pair of (Period, Duration), where the Period measures the difference up to a precision of days and the Duration represents the remainder:

Duration duration = Duration.between(start, end);
duration = duration.minusDays(duration.toDaysPart()); // essentially "duration (mod 1 day)"
Period period = Period.between(start.toLocalDate(), end.toLocalDate());

Now we can simply use the methods defined on Period and Duration to extract the individual units:

System.out.printf("%d years, %d months, %d days, %d hours, %d minutes, %d seconds",
        period.getYears(), period.getMonths(), period.getDays(), duration.toHoursPart(),
        duration.toMinutesPart(), duration.toSecondsPart());
1 years, 0 months, 1 days, 1 hours, 29 minutes, 0 seconds

or, using the default format:

System.out.println(period + " + " + duration);
P1Y1D + PT1H29M

Note on years, months & days

Note that, in java.time's conception, "units" like "month" or "year" don't represent a fixed, absolute temporal value—they're date- and calendar-dependent, as the following example illustrates:

        start1 = LocalDateTime.of(2020, 1, 1, 0, 0),
        end1 = LocalDateTime.of(2021, 1, 1, 0, 0),
        start2 = LocalDateTime.of(2021, 1, 1, 0, 0),
        end2 = LocalDateTime.of(2022, 1, 1, 0, 0);
System.out.println(Period.between(start1.toLocalDate(), end1.toLocalDate()));
System.out.println(Duration.between(start1, end1).toDays());
System.out.println(Period.between(start2.toLocalDate(), end2.toLocalDate()));
System.out.println(Duration.between(start2, end2).toDays());

CSS3 Continuous Rotate Animation (Just like a loading sundial)

You could use animation like this:

-webkit-animation: spin 1s infinite linear;

@-webkit-keyframes spin {
    0%   {-webkit-transform: rotate(0deg)}
    100% {-webkit-transform: rotate(360deg)}

bootstrap datepicker change date event doesnt fire up when manually editing dates or clearing date

This should make it work in both cases

function onDateChange() {
   // Do something here

$('#dpd1').bind('changeDate', onDateChange);
$('#dpd1').bind('input', onDateChange);

ES6 exporting/importing in index file

Too late but I want to share the way that I resolve it.

Having model file which has two named export:

export { Schema, Model };

and having controller file which has the default export:

export default Controller;

I exposed in the index file in this way:

import { Schema, Model } from './model';
import Controller from './controller';

export { Schema, Model, Controller };

and assuming that I want import all of them:

import { Schema, Model, Controller } from '../../path/';

Retrieving a random item from ArrayList


public static void main(String[] args) {
    RandomList<String> set = new RandomList<>();

    set.add("a", 10);
    set.add("b", 10);
    set.add("c", 30);
    set.add("d", 300);

    set.forEach((t) -> {

    HashMap<String, Integer> count = new HashMap<>();
    IntStream.range(0, 100).forEach((value) -> {
        String str = set.raffle();
        count.put(str, count.getOrDefault(str, 0) + 1);

    count.entrySet().stream().forEach(entry -> {
        System.out.println(String.format("%s: %s", entry.getKey(), entry.getValue()));






a: 2

b: 1

c: 9

d: 88

User GETDATE() to put current date into SQL variable

You can also use CURRENT_TIMESTAMP for this.

According to BOL CURRENT_TIMESTAMP is the ANSI SQL euivalent to GETDATE()

DECLARE @LastChangeDate AS DATE;

Can a constructor in Java be private?


This is so that you can control how the class is instantiated. If you make the constructor private, and then create a visible constructor method that returns instances of the class, you can do things like limit the number of creations (typically, guarantee there is exactly one instance) or recycle instances or other construction-related tasks.

Doing new x() never returns null, but using the factory pattern, you can return null, or even return different subtypes.

You might use it also for a class which has no instance members or properties, just static ones - as in a utility function class.

How do I make a Windows batch script completely silent?

If you want that all normal output of your Batch script be silent (like in your example), the easiest way to do that is to run the Batch file with a redirection:

C:\Temp> test.bat >nul

This method does not require to modify a single line in the script and it still show error messages in the screen. To supress all the output, including error messages:

C:\Temp> test.bat >nul 2>&1

If your script have lines that produce output you want to appear in screen, perhaps will be simpler to add redirection to those lineas instead of all the lines you want to keep silent:

SET scriptDirectory=%~dp0
COPY %scriptDirectory%test.bat %scriptDirectory%test2.bat
FOR /F %%f IN ('dir /B "%scriptDirectory%*.noext"') DO (
del "%scriptDirectory%%%f"
REM Next line DO appear in the screen
ECHO Script completed >con


How to get a list of properties with a given attribute?

There's always LINQ:

    p=>p.GetCustomAttributes(typeof(MyAttribute), true).Length != 0)

How to convert FileInputStream to InputStream?

If you wrap one stream into another, you don't close intermediate streams, and very important: You don't close them before finishing using the outer streams. Because you would close the outer stream too.

How to create nonexistent subdirectories recursively using Bash?

While existing answers definitely solve the purpose, if your'e looking to replicate nested directory structure under two different subdirectories, then you can do this

mkdir -p {main,test}/{resources,scala/com/company}

It will create following directory structure under the directory from where it is invoked

+-- main
¦   +-- resources
¦   +-- scala
¦       +-- com
¦           +-- company
+-- test
    +-- resources
    +-- scala
        +-- com
            +-- company

The example was taken from this link for creating SBT directory structure

Apply CSS rules to a nested class inside a div

Use Css Selector for this, or learn more about Css Selector just go here

#main_text > .title {
  /* Style goes here */

#main_text .title {
  /* Style goes here */

Android: Clear Activity Stack

In my case, LoginActivity was closed as well. As a result,


did not help.

However, setting


helped me.

Fit image to table cell [Pure HTML]

It's all about display: block :)


Ok so you have the table, tr and td tags:

      <!-- your image goes here -->

Lets say your table or td (whatever define your width) has property width: 360px;. Now, when you try to replace the html comment with the actual image and set that image property for example width: 100%; which should fully fill out the td cell you will face the problem.

The problem is that your table cell (td) isn't properly filled with the image. You'll notice the space at the bottom of the cell which your image doesn't cover (it's like 5px of padding).

How to solve this in a simpliest way?

You are working with the tables, right? You just need to add the display property to your image so that it has the following:

img {
  width: 100%;
  display: block;

Shuffle an array with python, randomize array item order with python

The other answers are the easiest, however it's a bit annoying that the random.shuffle method doesn't actually return anything - it just sorts the given list. If you want to chain calls or just be able to declare a shuffled array in one line you can do:

    import random
    def my_shuffle(array):
        return array

Then you can do lines like:

    for suit in my_shuffle(['hearts', 'spades', 'clubs', 'diamonds']):

Change the name of a key in dictionary

If you have a complex dict, it means there is a dict or list within the dict:

myDict = {1:"one",2:{3:"three",4:"four"}}
myDict[2][5] = myDict[2].pop(4)
print myDict

{1: 'one', 2: {3: 'three', 5: 'four'}}

How do I set Tomcat Manager Application User Name and Password for NetBeans?

One simple way to check your changes to that file in Tomcat 8 + is to open a browser to: http://localhost:8080/manager/text/list

How do I create a branch?

If you're repo is available via https, you can use this command to branch ...

svn copy \ \
  -m "Creating a branch of project"

Why does JSON.parse fail with the empty string?

For a valid JSON string at least a "{}" is required. See more at the

Securing a password in a properties file

enter image description here

Jasypt provides the class for loading, managing and transparently decrypting encrypted values in .properties files, allowing the mix of both encrypted and not-encrypted values in the same file.

By using an object, an application would be able to correctly read and use a .properties file like this:


Note that the database password is encrypted (in fact, any other property could also be encrypted, be it related with database configuration or not).

How do we read this value? like this:

* First, create (or ask some other component for) the adequate encryptor for   
* decrypting the values in our .properties file.   
StandardPBEStringEncryptor encryptor = new StandardPBEStringEncryptor();     
encryptor.setPassword("jasypt"); // could be got from web, env variable...    
* Create our EncryptableProperties object and load it the usual way.   
Properties props = new EncryptableProperties(encryptor);  
props.load(new FileInputStream("/path/to/my/"));

* To get a non-encrypted value, we just get it with getProperty...   
String datasourceUsername = props.getProperty("datasource.username");

* ...and to get an encrypted value, we do exactly the same. Decryption will   
* be transparently performed behind the scenes.   
String datasourcePassword = props.getProperty("datasource.password");

 // From now on, datasourcePassword equals "reports_passwd"...

rsync - mkstemp failed: Permission denied (13)

Make sure the user you're rsync'd into on the remote machine has write access to the contents of the folder AND the folder itself, as rsync tried to update the modification time on the folder itself.

How to insert a column in a specific position in oracle without dropping and recreating the table?


I don't believe you can add a column anywhere but at the end of the table once the table is created. One solution might be to try this:


Drop the table you want to add columns to:


It's at the point you could rebuild the existing table from scratch adding in the columns where you wish. Let's assume for this exercise you want to add the columns named "COL2 and COL3".

Now insert the data back into the new table:

SELECT COL1, 'Foo', 'Bar', COL4

When the data is inserted into your "new-old" table, you can drop the temp table.


This is often what I do when I want to add columns in a specific location. Obviously if this is a production on-line system, then it's probably not practical, but just one potential idea.


Laravel Eloquent: How to get only certain columns from joined tables

You can supply an array of fields in the get parameter like so:

return Response::eloquent(Theme::with('user')->get(array('user.username'));

UPDATE (for Laravel 5.2) From the docs, you can do this:

$response = DB::table('themes')
    ->select('themes.*', 'users.username')
    ->join('users', '', '=', 'themes.user_id')

postgresql sequence nextval in schema

SELECT last_value, increment_by from "other_schema".id_seq;

for adding a seq to a column where the schema is not public try this.


Is there an easy way to add a border to the top and bottom of an Android View?

Simply add Views at the top and bottom of the View

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

        app:layout_constraintStart_toStartOf="@+id/textView" />

        app:layout_constraintTop_toTopOf="parent" />

        app:layout_constraintTop_toBottomOf="@+id/textView" />