Programs & Examples On #Properties file

A .properties file is either a simple text file or an XML file containing pairs of keys and values. Java and related technologies frequently use .properties files to store configuration information.

Where to place and how to read configuration resource files in servlet based application?

Assume your code is looking for the file say Copy this file to any dir and add this dir to classpath, by creating a in the bin dir of tomcat.

In your of tomcat( if this file is not existing, create one , tomcat will load this file. #!/bin/sh CLASSPATH="$CLASSPATH:/home/user/config_my_prod/"

You should not have your properties files in ./webapps//WEB-INF/classes/

Tomcat class loader will override the with the one from WEB-INF/classes/

A good read:

Loading a properties file from Java package

Nobody mentions the similar but even simpler solution than above with no need to deal with the package of the class. Assuming is in the classpath.

        Properties properties = new Properties();
        InputStream in = ClassLoader.getSystemResourceAsStream("");


How to access a value defined in the file in Spring Boot

You can use @Value("${property-name}") from the if your class is annotated with @Configuration or @Component.

There's one more way I tried out was making a Utility class to read properties in the following way -

 protected PropertiesUtility () throws IOException {
    properties = new Properties();
    InputStream inputStream = 

You can make use of static method to get the value of the key passed as the parameter.

How to read an external properties file in Maven

Using the suggested Maven properties plugin I was able to read in a file that I use to version my builds.


How to read values from properties file?

Configure PropertyPlaceholder in your context:

<context:property-placeholder location="classpath*"/>

Then you refer to the properties in your beans:

class MyClass {
  private String[] myValues;

EDIT: updated the code to parse property with mutliple comma-separated values:,bbb,ccc

If that doesnt work, you can define a bean with properties, inject and process it manually:

<bean id="myProperties"
  <property name="locations">

and the bean:

class MyClass {
  private Properties myProperties;

  public void init() {
    // do whatever you need with properties

adding comment in .properties files

The property file task is for editing properties files. It contains all sorts of nice features that allow you to modify entries. For example:

<propertyfile file="">
    <entry key="build_number"

I've incremented my build_number by one. I have no idea what the value was, but it's now one greater than what it was before.

  • Use the <echo> task to build a property file instead of <propertyfile>. You can easily layout the content and then use <propertyfile> to edit that content later on.


<echo file="">
# Default Configuration
# Source Configuration
  • Create separate properties files for each section. You're allowed a comment header for each type. Then, use to batch them together into one single file:


<propertyfile file=""
    comment="Default Configuration">
    <entry key="source.dir" value="1"/>
    <entry key="dir.publish" value="1"/>

<propertyfile file=""
    comment="Source Configuration">
    <entry key="dir.publish.html" value="1"/>
<concat destfile="">
    <fileset dir="${basedir}">
        <include name=""/>
        <include name=""/>

    <fileset dir="${basedir}">
         <include name=""/>
        <include name=""/>

Spring .properties file: get element as an Array

With a Spring Boot one can do the following:


Configuration class

import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;

public class Configuration {

    List<String> values = new ArrayList<>();

    public List<String> getValues() {
        return values;


This is needed, without this class or without the values in class it is not working.

Spring Boot Application class

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.util.List;

public class SpringBootConsoleApplication implements CommandLineRunner {

    private static Logger LOG = LoggerFactory.getLogger(SpringBootConsoleApplication.class);

    // notice #{} is used instead of ${}
    List<String> values;

    public static void main(String[] args) {, args);

    public void run(String... args) {"values: {}", values);


ASP.NET postback with JavaScript

You can't call _doPostBack() because it forces submition of the form. Why don't you disable the PostBack on the UpdatePanel?

Is there a format code shortcut for Visual Studio?

ReSharper - Ctrl + Alt + F

Visual Studio 2010 - Ctrl + K, Ctrl + D

Compress images on client side before uploading

If you are looking for a library to carry out client-side image compression, you can check this out:compress.js. This will basically help you compress multiple images purely with JavaScript and convert them to base64 string. You can optionally set the maximum size in MB and also the preferred image quality.

How to respond with HTTP 400 error in a Spring MVC @ResponseBody method returning String?

I would change the implementation slightly:

First, I create a UnknownMatchException:

public class UnknownMatchException extends RuntimeException {
    public UnknownMatchException(String matchId) {
        super("Unknown match: " + matchId);

Note the use of @ResponseStatus, which will be recognized by Spring's ResponseStatusExceptionResolver. If the exception is thrown, it will create a response with the corresponding response status. (I also took the liberty of changing the status code to 404 - Not Found which I find more appropriate for this use case, but you can stick to HttpStatus.BAD_REQUEST if you like.)

Next, I would change the MatchService to have the following signature:

interface MatchService {
    public Match findMatch(String matchId);

Finally, I would update the controller and delegate to Spring's MappingJackson2HttpMessageConverter to handle the JSON serialization automatically (it is added by default if you add Jackson to the classpath and add either @EnableWebMvc or <mvc:annotation-driven /> to your config, see the reference docs):

@RequestMapping(value = "/matches/{matchId}", produces = MediaType.APPLICATION_JSON_VALUE)
public Match match(@PathVariable String matchId) {
    // throws an UnknownMatchException if the matchId is not known 
    return matchService.findMatch(matchId);

Note, it is very common to separate the domain objects from the view objects or DTO objects. This can easily be achieved by adding a small DTO factory that returns the serializable JSON object:

@RequestMapping(value = "/matches/{matchId}", produces = MediaType.APPLICATION_JSON_VALUE)
public MatchDTO match(@PathVariable String matchId) {
    Match match = matchService.findMatch(matchId);
    return MatchDtoFactory.createDTO(match);

When does Java's Thread.sleep throw InterruptedException?

The InterruptedException is usually thrown when a sleep is interrupted.

Pass multiple arguments into std::thread

You literally just pass them in std::thread(func1,a,b,c,d); that should have compiled if the objects existed, but it is wrong for another reason. Since there is no object created you cannot join or detach the thread and the program will not work correctly. Since it is a temporary the destructor is immediately called, since the thread is not joined or detached yet std::terminate is called. You could std::join or std::detach it before the temp is destroyed, like std::thread(func1,a,b,c,d).join();//or detach .

This is how it should be done.

std::thread t(func1,a,b,c,d);

You could also detach the thread, read-up on threads if you don't know the difference between joining and detaching.

what is difference between success and .done() method of $.ajax

success is the callback that is invoked when the request is successful and is part of the $.ajax call. done is actually part of the jqXHR object returned by $.ajax(), and replaces success in jQuery 1.8.

How to fix Error: laravel.log could not be opened?

In Laravel, you should set ACL on storage and cache directory so that web server user can read/write on the directory. Open a new terminal and run following:

HTTPDUSER=$(ps axo user,comm | grep -E '[a]pache|[h]ttpd|[_]www|[w]ww-data|[n]ginx' | grep -v root | head -1 | cut -d\  -f1)

sudo setfacl -dR -m u:"$HTTPDUSER":rwX -m u:$(whoami):rwX bootstrap/cache storage/
sudo setfacl -R -m u:"$HTTPDUSER":rwX -m u:$(whoami):rwX bootstrap/cache storage/


how to set JAVA_OPTS for Tomcat in Windows?

This is because, the amount of memory you wish to assign for JVM is not available or may be you are assigning more than available memory. Try small size then u can see the difference.

set JAVA_OPTS=-Xms128m -Xmx512m -XX:PermSize=128m

In C#, should I use string.Empty or String.Empty or "" to intitialize a string?

It doesn't matter - they are exactly the same thing. However, the main thing is that you must be consistent

p.s. I struggle with this sort of "whats the right thing" all the time.

How can I put a ListView into a ScrollView without it collapsing?

There's a built-in setting for it. On the ScrollView:


In Java,


Romain Guy explains it in depth here:

How to find the index of an element in an int array?

Copy this method into your class

 public int getArrayIndex(int[] arr,int value) {

        int k=0;
        for(int i=0;i<arr.length;i++){

    return k;

Call this method with pass two perameters Array and value and store its return value in a integer variable.

int indexNum = getArrayIndex(array,value);

Thank you

The name 'controlname' does not exist in the current context

1) Check the CodeFile property in <%@Page CodeFile="filename.aspx.cs" %> in "filename.aspx" page , your Code behind file name and this Property name should be same.

2)you may miss runat="server" in code

How to align an indented line in a span that wraps into multiple lines?


then you've got a block element and the margin is added to all lines.

While it's true that a span is semantically not a block element, there are cases where you don't have control of the pages DOM. This answer is inteded for those.

Difference between Xms and Xmx and XX:MaxPermSize

Java objects reside in an area called the heap, while metadata such as class objects and method objects reside in the permanent generation or Perm Gen area. The permanent generation is not part of the heap.

The heap is created when the JVM starts up and may increase or decrease in size while the application runs. When the heap becomes full, garbage is collected. During the garbage collection objects that are no longer used are cleared, thus making space for new objects.

-Xmssize Specifies the initial heap size.

-Xmxsize Specifies the maximum heap size.

-XX:MaxPermSize=size Sets the maximum permanent generation space size. This option was deprecated in JDK 8, and superseded by the -XX:MaxMetaspaceSize option.

Sizes are expressed in bytes. Append the letter k or K to indicate kilobytes, m or M to indicate megabytes, g or G to indicate gigabytes.


How is the java memory pool divided?

What is perm space?

Java (JVM) Memory Model – Memory Management in Java

Java 7 SE Command Line Options

Java 7 HotSpot VM Options

How to directly move camera to current location in Google Maps Android API v2?

make sure you have these permissions:

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

Then make some activity and register a LocationListener

package com.example.location;

import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.view.View;

public class LocationActivity extends SherlockFragmentActivity implements LocationListener     {
private GoogleMap map;
private LocationManager locationManager;
private static final long MIN_TIME = 400;
private static final float MIN_DISTANCE = 1000;

protected void onCreate(Bundle savedInstanceState) {
    map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(;

    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, MIN_TIME, MIN_DISTANCE, this); //You can also use LocationManager.GPS_PROVIDER and LocationManager.PASSIVE_PROVIDER        

public void onLocationChanged(Location location) {
    LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
    CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(latLng, 10);

public void onStatusChanged(String provider, int status, Bundle extras) { }

public void onProviderEnabled(String provider) { }

public void onProviderDisabled(String provider) { }


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

How to handle Uncaught (in promise) DOMException: The play() request was interrupted by a call to pause()

For Chrome they changed autoplay policy, so you can read about here:

var promise = document.querySelector('audio').play();

if (promise !== undefined) {
    promise.then(_ => {
        // Autoplay started!
    }).catch(error => {
        // Autoplay was prevented.
        // Show a "Play" button so that user can start playback.

SQL Server convert string to datetime

For instance you can use

update tablename set datetimefield='19980223 14:23:05'
update tablename set datetimefield='02/23/1998 14:23:05'
update tablename set datetimefield='1998-12-23 14:23:05'
update tablename set datetimefield='23 February 1998 14:23:05'
update tablename set datetimefield='1998-02-23T14:23:05'

You need to be careful of day/month order since this will be language dependent when the year is not specified first. If you specify the year first then there is no problem; date order will always be year-month-day.

Remove all occurrences of char from string

Use replaceAll instead of replace

str = str.replaceAll("X,"");

This should give you the desired answer.

Laravel 5 call a model function in a blade view

I solve the problem. So simple. Syntax error.

  • App\Product
  • App\Service

enter image description here

But I also want to know how to pass a function with parameters to view....

Can anyone explain what JSONP is, in layman terms?

I have found a useful article that also explains the topic quite clearly and easy language. Link is JSONP

Some of the worth noting points are:

  1. JSONP pre-dates CORS.
  2. It is a pseudo-standard way to retreive data from a different domain,
  3. It has limited CORS features (only GET method)

Working is as follows:

  1. <script src="url?callback=function_name"> is included in the html code
  2. When step 1 gets executed it sens a function with the same function name (as given in the url parameter) as a response.
  3. If the function with the given name exists in the code, it will be executed with the data, if any, returned as an argument to that function.

How To Convert A Number To an ASCII Character?

C# represents a character in UTF-16 coding rather than ASCII. Therefore converting a integer to character do not make any difference for A-Z and a-z. But I was working with ASCII Codes besides alphabets and number which did not work for me as system uses UTF-16 code. Therefore I browsed UTF-16 code for all UTF-16 character. Here is the module :

void utfchars()
 int i, a, b, x;
 ConsoleKeyInfo z;
   a = 0; b = 0; Console.Clear();
    for (i = 1; i <= 10000; i++)
     if (b == 20)
      b = 0;
      a = a + 1;
    Console.SetCursorPosition((a * 15) + 1, b + 1);
    Console.Write("{0} == {1}", i, (char)i);
   b = b+1;
   if (i % 100 == 0)
 Console.Write("\n\t\t\tPress any key to continue {0}", b);
 a = 0; b = 0;
 Console.ReadKey(true); Console.Clear();
Console.Write("\n\n\n\n\n\n\n\t\t\tPress any key to Repeat and E to exit");
z = Console.ReadKey();
if (z.KeyChar == 'e' || z.KeyChar == 'E') Environment.Exit(0);
} while (1 == 1);

How to split a string in Haskell?

There is a package for this called split.

cabal install split

Use it like this:

ghci> import Data.List.Split
ghci> splitOn "," "my,comma,separated,list"

It comes with a lot of other functions for splitting on matching delimiters or having several delimiters.

How to efficiently check if variable is Array or Object (in NodeJS & V8)?

Hi I know this topic is old but there is a much better way to differentiate an Array in Node.js from any other Object have a look at the docs.

var util = require('util');

util.isArray([]); // true
util.isArray({}); // false

var obj = {};
typeof obj === "Object" // true

How to delete an app from iTunesConnect / App Store Connect


(as of 2021)

Click your app, click App Information in the left side menu, scroll all the way down to the Additional Information section, click Remove App.

Boom. done.

Cannot deserialize instance of object out of START_ARRAY token in Spring Webservice

I've had a very similar issue using spring-boot-starter-data-redis. To my implementation there was offered a @Bean for RedisTemplate as follows:

public RedisTemplate<String, List<RoutePlantCache>> redisTemplate(RedisConnectionFactory connectionFactory) {
    final RedisTemplate<String, List<RoutePlantCache>> template = new RedisTemplate<>();
    template.setKeySerializer(new StringRedisSerializer());
    template.setValueSerializer(new Jackson2JsonRedisSerializer<>(RoutePlantCache.class));

    // Add some specific configuration here. Key serializers, etc.
    return template;

The fix was to specify an array of RoutePlantCache as following:

template.setValueSerializer(new Jackson2JsonRedisSerializer<>(RoutePlantCache[].class));

Below the exception I had:

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `[...].RoutePlantCache` out of START_ARRAY token
 at [Source: (byte[])"[{ ... },{ ... [truncated 1478 bytes]; line: 1, column: 1]
    at com.fasterxml.jackson.databind.exc.MismatchedInputException.from( ~[jackson-databind-2.11.4.jar:2.11.4]
    at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch( ~[jackson-databind-2.11.4.jar:2.11.4]
    at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken( ~[jackson-databind-2.11.4.jar:2.11.4]
    at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken( ~[jackson-databind-2.11.4.jar:2.11.4]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeFromArray( ~[jackson-databind-2.11.4.jar:2.11.4]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther( ~[jackson-databind-2.11.4.jar:2.11.4]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize( ~[jackson-databind-2.11.4.jar:2.11.4]
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose( ~[jackson-databind-2.11.4.jar:2.11.4]
    at com.fasterxml.jackson.databind.ObjectMapper.readValue( ~[jackson-databind-2.11.4.jar:2.11.4]

How do I check how many options there are in a dropdown menu?

$('#idofdropdown option').length;

That should do it.

Append String in Swift

Strings concatenate in Swift language.

let string1 = "one"

let string2 = "two"

var concate = " (string1) (string2)"

playgroud output is "one two"

Plotting two variables as lines using ggplot2 on the same graph

I am also new to R but trying to understand how ggplot works I think I get another way to do it. I just share probably not as a complete perfect solution but to add some different points of view.

I know ggplot is made to work with dataframes better but maybe it can be also sometimes useful to know that you can directly plot two vectors without using a dataframe.

Loading data. Original date vector length is 100 while var0 and var1 have length 50 so I only plot the available data (first 50 dates).

var0 <- 100 + c(0, cumsum(runif(49, -20, 20)))
var1 <- 150 + c(0, cumsum(runif(49, -10, 10)))
date <- seq(as.Date("2002-01-01"), by="1 month", length.out=50)    


ggplot() + geom_line(aes(x=date,y=var0),color='red') + 
           geom_line(aes(x=date,y=var1),color='blue') + 

enter image description here

However I was not able to add a correct legend using this format. Does anyone know how?

Print new output on same line

>>> for i in range(1, 11):
...     print(i, end=' ')
...     if i==len(range(1, 11)): print()
1 2 3 4 5 6 7 8 9 10 

This is how to do it so that the printing does not run behind the prompt on the next line.

How do I check if a string is a number (float)?

In case you are looking for parsing (positive, unsigned) integers instead of floats, you can use the isdigit() function for string objects.

>>> a = "03523"
>>> a.isdigit()
>>> b = "963spam"
>>> b.isdigit()

String Methods - isdigit(): Python2, Python3

There's also something on Unicode strings, which I'm not too familiar with Unicode - Is decimal/decimal

The FastCGI process exited unexpectedly

For Issue C:\PHP\php-cgi.exe - The FastCGI process exited unexpectedly.

I resolved this by installing the Visual C++ Redistributable for Visual Studio 2015.(Microsoft Visual C++ 2015 Redistributable Update 3) and Visual C++ Redistributable for Visual Studio 2012 Update 4 in 32 and 64bit versions. and also make sure in file cgi.fix_pathinfo=0 enabled.

IsNumeric function in c#

menu: Project-->Add Reference

click: assemblies, framework

Put a checkmark on Microsoft.VisualBasic.

Hit OK.

That link is for Visual Studio 2013, you can use the "Other versions" dropdown for different versions of visual studio.

In all cases you need to add a reference to the .NET assembly "Microsoft.VisualBasic".

At the top of your c# file you neeed:

using Microsoft.VisualBasic;

Then you can look at writing the code.

The code would be something like:

   private void btnOK_Click(object sender, EventArgs e)
      if ( Information.IsNumeric(startingbudget) )
         MessageBox.Show("This is a number.");

List passed by ref - help me explain this behaviour

You are passing a reference to the list, but your aren't passing the list variable by reference - so when you call ChangeList the value of the variable (i.e. the reference - think "pointer") is copied - and changes to the value of the parameter inside ChangeList aren't seen by TestMethod.


private void ChangeList(ref List<int> myList) {...}
ChangeList(ref myList);

This then passes a reference to the local-variable myRef (as declared in TestMethod); now, if you reassign the parameter inside ChangeList you are also reassigning the variable inside TestMethod.

How can I sort one set of data to match another set of data in Excel?

You could also simply link both cells, and have an =Cell formula in each column like, =Sheet2!A2 in Sheet 1 A2 and =Sheet2!B2 in Sheet 1 B2, and drag it down, and then sort those two columns the way you want.

  • If they don't sort the way you want, put the order you want to sort them in another column and sort all three columns by that.
  • If you drag it down further and get zeros you can edit the =Cell formula to show "" IF there is nothing. =(if(cell="","",cell)
  • Cutting, pasting, deleting, and inserting rows is something to be weary of. #REF! errors could occur.

This would be better if your unique items change also, then all you would do is sort and be done.

Get just the filename from a path in a Bash script

basename and dirname solutions are more convenient. Those are alternative commands:

echo "$FILE_PATH" | sed "s/.*\///"

This returns test.old.img like basename.

This is salt filename without extension:

echo "$FILE_PATH" | sed -r "s/.+\/(.+)\..+/\1/"

It returns test.old.

And following statement gives the full path like dirname command.

echo "$FILE_PATH" | sed -r "s/(.+)\/.+/\1/"

It returns /opt/datastores/sda2

What is the use of WPFFontCache Service in WPF? WPFFontCache_v0400.exe taking 100 % CPU all the time this exe is running, why?

for win xp


  1. [windows key] + R, type services.msc, search for the running instance of "Windows Presentation Foundation (WPF) Font Cache". For my case its 4.0. Stop the service.
  2. [windows key] + R, type C:\Documents and Settings\LocalService\Local Settings\Application Data\, delete all font cache files.
  3. Start the "Windows Presentation Foundation (WPF) Font Cache" service.

Get raw POST body in Python Flask regardless of Content-Type header

I created a WSGI middleware that stores the raw body from the environ['wsgi.input'] stream. I saved the value in the WSGI environ so I could access it from request.environ['body_copy'] within my app.

This isn't necessary in Werkzeug or Flask, as request.get_data() will get the raw data regardless of content type, but with better handling of HTTP and WSGI behavior.

This reads the entire body into memory, which will be an issue if for example a large file is posted. This won't read anything if the Content-Length header is missing, so it won't handle streaming requests.

from io import BytesIO

class WSGICopyBody(object):
    def __init__(self, application):
        self.application = application

    def __call__(self, environ, start_response):
        length = int(environ.get('CONTENT_LENGTH') or 0)
        body = environ['wsgi.input'].read(length)
        environ['body_copy'] = body
        # replace the stream since it was exhausted by read()
        environ['wsgi.input'] = BytesIO(body)
        return self.application(environ, start_response)

app.wsgi_app = WSGICopyBody(app.wsgi_app)

Insert auto increment primary key to existing table

How to write PHP to ALTER the already existing field (name, in this example) to make it a primary key? W/o, of course, adding any additional 'id' fields to the table..

This a table currently created - Number of Records found: 4 name VARCHAR(20) YES breed VARCHAR(30) YES color VARCHAR(20) YES weight SMALLINT(7) YES

This an end result sought (TABLE DESCRIPTION) -

Number of records found: 4 name VARCHAR(20) NO PRI breed VARCHAR(30) YES color VARCHAR(20) YES weight SMALLINT(7) YES

Instead of getting this -

Number of Records found: 5 id int(11) NO PRI name VARCHAR(20) YES breed VARCHAR(30) YES color VARCHAR(20) YES weight SMALLINT(7) YES

after trying..


how to get this? -

Number of records found: 4 name VARCHAR(20) NO PRI breed VARCHAR(30) YES color VARCHAR(20) YES weight SMALLINT(7) YES

i.e. INSERT/ADD.. etc. the primary key INTO the first field record (w/o adding an additional 'id' field, as stated earlier.

Convert a Unix timestamp to time in JavaScript


var s = new Date(1504095567183).toLocaleDateString("en-US")
// expected output "8/30/2017"  

and for time:

var s = new Date(1504095567183).toLocaleTimeString("en-US")
// expected output "3:19:27 PM"

see Date.prototype.toLocaleDateString()

How do you normalize a file path in Bash?

Use the readlink utility from the coreutils package.

MY_PATH=$(readlink -f "$0")

AttributeError: Module Pip has no attribute 'main'

I faced the same error while using pip on anaconda3 4.4.0 (python 3.6) on windows.

I fixed the problem by the following command:

easy_install pip==18.*  ### installing the latest version pip

Or if lower version pip required, mention the same in the command.

Or you can try installing the lower version and then upgrading the same to latest version as follow:

easy_install pip==9.0.1

easy_install --upgrade pip

How to read request body in an core webapi controller?

The simplest possible way to do this is the following:

  1. In the Controller method you need to extract the body from, add this parameter: [FromBody] SomeClass value

  2. Declare the "SomeClass" as: class SomeClass { public string SomeParameter { get; set; } }

When the raw body is sent as json, .net core knows how to read it very easily.

How to insert newline in string literal?

If you want a const string that contains Environment.NewLine in it you can do something like this:

const string stringWithNewLine =
@"first line
second line
third line";


Since this is in a const string it is done in compile time therefore it is the compiler's interpretation of a newline. I can't seem to find a reference explaining this behavior but, I can prove it works as intended. I compiled this code on both Windows and Ubuntu (with Mono) then disassembled and these are the results:

Disassemble on Windows Disassemble on Ubuntu

As you can see, in Windows newlines are interpreted as \r\n and on Ubuntu as \n

Margin-Top not working for span element?

Looks like you missed some options, try to add:

position: relative;
top: 25px;

Any way to break if statement in PHP?

$arr=array('test','go for it');
foreach($arr as $val){
  $output = 'test';
  if($val === $a) $output = "";
  echo $output;
echo "finish";

combining your statements, i think this would give you your wished result. clean and simple, without having too much statements.

for the ugly and good looking code, my recomandation would be:

function myfunction(){
  if( !process_x() || !process_y() || !process_z()) {
/*do all the stuff you need to do*/

somewhere in your normal code


How to trim leading and trailing white spaces of a string?

Just as @Kabeer has mentioned, you can use TrimSpace and here is an example from golang documentation:

package main

import (

func main() {
    fmt.Println(strings.TrimSpace(" \t\n Hello, Gophers \n\t\r\n"))

How to get the host name of the current machine as defined in the Ansible hosts file?

The necessary variable is inventory_hostname.

- name: Install this only for local dev machine
  pip: name=pyramid
  when: inventory_hostname == "local"

It is somewhat hidden in the documentation at the bottom of this section.

Database Diagram Support Objects cannot be Installed ... no valid owner

Select your database - Right Click - Select Properties

Select FILE in left side of page

In the OWNER box, select button which has three dots (…) in it

Now select user ‘sa and Click OK

How do I find the current directory of a batch file, and then use it for the path?

Try in yourbatch

set "batchisin=%~dp0"

which should set the variable to your batch's location.

"The breakpoint will not currently be hit. The source code is different from the original version." What does this mean?

If your debugged process contains multiple appdomains and the assembly is loaded into both, and one of them is loading an old copy (usually something dynamically loaded like a plugin) the breakpoint can appear solid, but the thread that should hit the breakpoint is in the appdomain with the old assembly, and never hits. You can see what assemblies are loaded and their path in the module window.

Python vs Bash - In which kind of tasks each one outruns the other performance-wise?

If you are looking to cobble together a quick utility with minimal effort, bash is good. For a wrapper round an application, bash is invaluable.

Anything that may have you coming back over and over to add improvements is probably (though not always) better suited to a language like Python as Bash code comprising over a 1000 lines gets very painful to maintain. Bash code is also irritating to debug when it gets long.......

Part of the problem with these kind of questions is, from my experience, that shell scripts are usually all custom tasks. There have been very few shell scripting tasks that I have come across where there is already a solution freely available.

SyntaxError: "can't assign to function call"

You wrote the assignment backward: to assign a value (or an expression) to a variable you must have that variable at the left side of the assignment operator ( = in python )

subsequent_amount = invest(initial_amount,top_company(5,year,year+1))

How to print a linebreak in a python function?

You can print a native linebreak using the standard os library

import os
with open('test.txt','w') as f:

The application has stopped unexpectedly: How to Debug?

If you use the Logcat display inside the 'debug' perspective in Eclipse the lines are colour-coded. It's pretty easy to find what made your app crash because it's usually in red.

The Java (or Dalvik) virtual machine should never crash, but if your program throws an exception and does not catch it the VM will terminate your program, which is the 'crash' you are seeing.

Accessing inventory host variable in Ansible playbook

I struggled with this, too. My specific setup is: Your host.ini (with the modern names):

test3-1 ansible_host=abc.def.ghi.pqr ansible_port=1212
test3-2 ansible_host=abc.def.ghi.stu ansible_port=1212

plus a play fill_file.yml

- remote_user: ec2-user
  hosts: test3
   - name: fill file
       src: file.j2
       dest: filled_file.txt

plus a template file.j2 , like

{% for host in groups['test3'] %}
   {{ hostvars[host].ansible_host }}
{% endfor %}

This worked for me, the result is


I have to admit it's ansible 2.7, not 2.1. The template is a variation of an example in

The accepted answer didn't work in my setup. With a template

{{ hostvars['test3'].ansible_host }}

my play fails with "AnsibleUndefinedVariable: \"hostvars['test3']\" is undefined" .

Remark: I tried some variations, but failed, occasionally with "ansible.vars.hostvars.HostVars object has no element "; Some of this might be explained by what they say. in

hostvars emulates a dictionary [...]. hostvars is also lazily loaded

How can I get a list of all values in select box?

You had two problems:

1) The order in which you included the HTML. Try changing the dropdown from "onLoad" to "no wrap - head" in the JavaScript settings of your fiddle.

2) Your function prints the values. What you're actually after is the text

x.options[i].text; instead of x.options[i].value;

Time stamp in the C programming language

 Returns the current time.

char *time_stamp(){

char *timestamp = (char *)malloc(sizeof(char) * 16);
time_t ltime;
struct tm *tm;

sprintf(timestamp,"%04d%02d%02d%02d%02d%02d", tm->tm_year+1900, tm->tm_mon, 
    tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
return timestamp;

int main(){

printf(" Timestamp: %s\n",time_stamp());
return 0;


Output: Timestamp: 20110912130940 // 2011 Sep 12 13:09:40

changing permission for files and folder recursively using shell command in mac

The issue is that the * is getting interpreted by your shell and is expanding to a file named TEST_FILE that happens to be in your current working directory, so you're telling find to execute the command named TEST_FILE which doesn't exist. I'm not sure what you're trying to accomplish with that *, you should just remove it.

Furthermore, you should use the idiom -exec program '{}' \+ instead of -exec program '{}' \; so that find doesn't fork a new process for each file. With ;, a new process is forked for each file, whereas with +, it only forks one process and passes all of the files on a single command line, which for simple programs like chmod is much more efficient.

Lastly, chmod can do recursive changes on its own with the -R flag, so unless you need to search for specific files, just do this:

chmod -R 777 /Users/Test/Desktop/PATH

Cannot connect to local SQL Server with Management Studio

Same as matt said. The "SQL Server(SQLEXPRESS)" was stopped. Enabled it by opening Control Panel > Administrative Tools > Services, right-clicking on the "SQL Server(SQLEXPRESS)" service and selecting "Start" from the available options. Could connect fine after that.

Get DOM content of cross-domain iframe

There is a simple way.

  1. You create an iframe which have for source something like "

  2. Then, you just get this url with $_GET and display the contents with file_get_contents($_GET['url']);

You will obtain an iframe which has a domain same than yours, then you will be able to use the $("iframe").contents().find("body") to manipulate the content.

CSS3 gradient background set on body doesn't stretch but instead repeats?

There is a lot of partial information on this page, but not a complete one. Here is what I do:

  1. Create a gradient here:
  2. Set gradient on HTML instead of BODY.
  3. Fix the background on HTML with "background-attachment: fixed;"
  4. Turn off the top and bottom margins on BODY
  5. (optional) I usually create a <DIV id='container'> that I put all of my content in

Here is an example:

html {  
  background: #a9e4f7; /* Old browsers */
  background: -moz-linear-gradient(-45deg,  #a9e4f7 0%, #0fb4e7 100%); /* FF3.6+ */
  background: -webkit-gradient(linear, left top, right bottom, color-stop(0%,#a9e4f7), color-stop(100%,#0fb4e7)); /* Chrome,Safari4+ */ 
  background: -webkit-linear-gradient(-45deg,  #a9e4f7 0%,#0fb4e7 100%); /* Chrome10+,Safari5.1+ */
  background: -o-linear-gradient(-45deg,  #a9e4f7 0%,#0fb4e7 100%); /* Opera 11.10+ */
  background: -ms-linear-gradient(-45deg,  #a9e4f7 0%,#0fb4e7 100%); /* IE10+ */
  background: linear-gradient(135deg,  #a9e4f7 0%,#0fb4e7 100%); /* W3C */ 
  filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#a9e4f7', endColorstr='#0fb4e7',GradientType=1 ); /* IE6-9 fallback on horizontal gradient */

  background-attachment: fixed;

body {
  margin-top: 0px;
  margin-bottom: 0px;

/* OPTIONAL: div to store content.  Many of these attributes should be changed to suit your needs */
  width: 800px;
  margin: auto;
  background-color: white;
  border: 1px solid gray;
  border-top: none;
  border-bottom: none;
  box-shadow: 3px 0px 20px #333;
  padding: 10px;

This has been tested with IE, Chrome, and Firefox on pages of various sizes and scrolling needs.

Excluding directory when creating a .tar.gz file

Try removing the last / at the end of the directory path to exclude

tar -pczf MyBackup.tar.gz /home/user/public_html/ --exclude "/home/user/public_html/tmp" 

Using Switch Statement to Handle Button Clicks

One mistake what i did was not including "implements OnClickListener" in the main class declaration. This is a sample code to clearly illustrate the use of switch case during on click. The code changes background colour as per the button pressed. Hope this helps.

public class MainActivity extends Activity  implements OnClickListener{

TextView displayText;
Button cred, cblack, cgreen, cyellow, cwhite;
LinearLayout buttonLayout;

protected void onCreate(Bundle savedInstanceState) {

    cred = (Button) findViewById(;
    cblack = (Button) findViewById(;
    cgreen = (Button) findViewById(;
    cyellow = (Button) findViewById(;
    cwhite = (Button) findViewById(;
    displayText = (TextView) findViewById(;
    buttonLayout = (LinearLayout) findViewById(;


protected void onClick(View V){
    int id=V.getId();
        displayText.setBackgroundColor(Color.rgb(255, 0, 0));
        displayText.setBackgroundColor(Color.rgb(0, 0, 0));
        displayText.setBackgroundColor(Color.rgb(255, 255, 0));
        displayText.setBackgroundColor(Color.rgb(0, 255, 0));
        displayText.setBackgroundColor(Color.rgb(255, 255, 255));

How to apply an XSLT Stylesheet in C#

This might help you

public static string TransformDocument(string doc, string stylesheetPath)
    Func<string,XmlDocument> GetXmlDocument = (xmlContent) =>
         XmlDocument xmlDocument = new XmlDocument();
         return xmlDocument;

        var document = GetXmlDocument(doc);
        var style = GetXmlDocument(File.ReadAllText(stylesheetPath));

        System.Xml.Xsl.XslCompiledTransform transform = new System.Xml.Xsl.XslCompiledTransform();
        transform.Load(style); // compiled stylesheet
        System.IO.StringWriter writer = new System.IO.StringWriter();
        XmlReader xmlReadB = new XmlTextReader(new StringReader(document.DocumentElement.OuterXml));
        transform.Transform(xmlReadB, null, writer);
        return writer.ToString();
    catch (Exception ex)
        throw ex;


Round button with text and icon in flutter


enter image description here

  size: Size(56, 56), // button width and height
  child: ClipOval(
    child: Material(
      color:, // button color
      child: InkWell(
        splashColor:, // splash color
        onTap: () {}, // button pressed
        child: Column(
          children: <Widget>[
            Icon(, // icon
            Text("Call"), // text

Calling a particular PHP function on form submit

An alternative, and perhaps a not so good procedural coding one, is to send the "function name" to a script that then executes the function. For instance, with a login form, there is typically the login, forgotusername, forgotpassword, signin activities that are presented on the form as buttons or anchors. All of these can be directed to/as, say,


And then a switch statement on the receiving page does any prep work and then dispatches or runs the (next) specified function.

How To Accept a File POST

I used Mike Wasson's answer before I updated all the NuGets in my webapi mvc4 project. Once I did, I had to re-write the file upload action:

    public Task<HttpResponseMessage> Upload(int id)
        HttpRequestMessage request = this.Request;
        if (!request.Content.IsMimeMultipartContent())
            throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.UnsupportedMediaType));

        string root = System.Web.HttpContext.Current.Server.MapPath("~/App_Data/uploads");
        var provider = new MultipartFormDataStreamProvider(root);

        var task = request.Content.ReadAsMultipartAsync(provider).
            ContinueWith<HttpResponseMessage>(o =>
                FileInfo finfo = new FileInfo(provider.FileData.First().LocalFileName);

                string guid = Guid.NewGuid().ToString();

                File.Move(finfo.FullName, Path.Combine(root, guid + "_" + provider.FileData.First().Headers.ContentDisposition.FileName.Replace("\"", "")));

                return new HttpResponseMessage()
                    Content = new StringContent("File uploaded.")
        return task;

Apparently BodyPartFileNames is no longer available within the MultipartFormDataStreamProvider.

Scala check if element is present in a list

In your case I would consider using Set and not List, to ensure you have unique values only. unless you need sometimes to include duplicates.

In this case, you don't need to add any wrapper functions around lists.

Sort an array of objects in React and render them

Chrome browser considers integer value as return type not boolean value so,, b) => a.item.timeM > b.item.timeM ? 1:-1).map(
    (item, i) => <div key={i}> {item.matchID} {item.timeM} {item.description}</div>

How to disable right-click context-menu in JavaScript

You can't rely on context menus because the user can deactivate it. Most websites want to use the feature to annoy the visitor.

How to fetch Java version using single line command in Linux

This way works for me.

# java -version 2>&1|awk '/version/ {gsub("\"","") ; print $NF}'


Drop columns whose name contains a specific string from pandas DataFrame

Solution when dropping a list of column names containing regex. I prefer this approach because I'm frequently editing the drop list. Uses a negative filter regex for the drop list.

drop_column_names = ['A','B.+','C.*']
drop_columns_regex = '^(?!(?:'+'|'.join(drop_column_names)+')$)'
print('Dropping columns:',', '.join([c for c in df.columns if,c)]))
df = df.filter(regex=drop_columns_regex,axis=1)

How to redirect to another page using PHP


if($insert = mysqli_query($con,"update  consumer_closeconnection set close_status='Pending' where id="$id"  "))


Java: Instanceof and Generics

Provided your class extends a class with a generic parameter, you can also get this at runtime via reflection, and then use that for comparison, i.e.

class YourClass extends SomeOtherClass<String>

   private Class<?> clazz;

   public Class<?> getParameterizedClass()
      if(clazz == null)
         ParameterizedType pt = (ParameterizedType)this.getClass().getGenericSuperclass();
          clazz = (Class<?>)pt.getActualTypeArguments()[0];
       return clazz;

In the case above, at runtime you will get String.class from getParameterizedClass(), and it caches so you don't get any reflection overhead upon multiple checks. Note that you can get the other parameterized types by index from the ParameterizedType.getActualTypeArguments() method.

Why a function checking if a string is empty always returns true?

In your if clause in the function, you're referring to a variable strTemp that doesn't exist. $strTemp does exist, though.

But PHP already has an empty() function available; why make your own?

if (empty($str))
    /* String is empty */
    /* Not empty */


Return Values

Returns FALSE if var has a non-empty and non-zero value.

The following things are considered to be empty:

* "" (an empty string)
* 0 (0 as an integer)
* "0" (0 as a string)
* array() (an empty array)
* var $var; (a variable declared, but without a value in a class)

python - if not in list

Your code should work, but you can also try:

    if not item in mylist :

How to error handle 1004 Error with WorksheetFunction.VLookup?

From my limited experience, this happens for two main reasons:

  1. The lookup_value (arg1) is not present in the table_array (arg2)

The simple solution here is to use an error handler ending with Resume Next

  1. The formats of arg1 and arg2 are not interpreted correctly

If your lookup_value is a variable you can enclose it with TRIM()

cellNum = wsFunc.VLookup(TRIM(currName), rngLook, 13, False)

What does FETCH_HEAD in Git mean?

I have just discovered and used FETCH_HEAD. I wanted a local copy of some software from a server and I did

git fetch gitserver release_1

gitserver is the name of my machine that stores git repositories. release_1 is a tag for a version of the software. To my surprise, release_1 was then nowhere to be found on my local machine. I had to type

 git tag release_1 FETCH_HEAD 

to complete the copy of the tagged chain of commits (release_1) from the remote repository to the local one. Fetch had found the remote tag, copied the commit to my local machine, had not created a local tag, but had set FETCH_HEAD to the value of the commit, so that I could find and use it. I then used FETCH_HEAD to create a local tag which matched the tag on the remote. That is a practical illustration of what FETCH_HEAD is and how it can be used, and might be useful to someone else wondering why git fetch doesn't do what you would naively expect.

In my opinion it is best avoided for that purpose and a better way to achieve what I was trying to do is

git fetch gitserver release_1:release_1

i.e. to fetch release_1 and call it release_1 locally. (It is source:dest, see; just in case you'd like to give it a different name!)

You might want to use FETCH_HEAD at times though:-

git fetch gitserver bugfix1234
git cherry-pick FETCH_HEAD

might be a nice way of using bug fix number 1234 from your Git server, and leaving Git's garbage collection to dispose of the copy from the server once the fix has been cherry-picked onto your current branch. (I am assuming that there is a nice clean tagged commit containing the whole of the bug fix on the server!)

How to search for a part of a word with ElasticSearch

Try the solution with is described here: Exact Substring Searches in ElasticSearch

    "mappings": {
        "my_type": {
    "settings": {
        "analysis": {
            "filter": {
                "ngram_filter": {
                    "type": "ngram",
                    "min_gram": 3,
                    "max_gram": 8
            "analyzer": {
                "index_ngram": {
                    "type": "custom",
                    "tokenizer": "keyword",
                    "filter": [ "ngram_filter", "lowercase" ]
                "search_ngram": {
                    "type": "custom",
                    "tokenizer": "keyword",
                    "filter": "lowercase"

To solve the disk usage problem and the too-long search term problem short 8 characters long ngrams are used (configured with: "max_gram": 8). To search for terms with more than 8 characters, turn your search into a boolean AND query looking for every distinct 8-character substring in that string. For example, if a user searched for large yard (a 10-character string), the search would be:

"arge ya AND arge yar AND rge yard.

How to show validation message below each textbox using jquery?

Here you go:


$('form').on('submit', function (e) {

    if (!$('#email').val()) 
        $('#email').parent().append('<span class="error">Please enter your email address.</span>');

         $('#password').parent().append('<span class="error">Please enter your password.</span>');


@charset "utf-8";
/* CSS Document */

/* ---------- FONTAWESOME ---------- */
/* ---------- ---------- */
/* ---------- ---------- */

@import url(;

/* ---------- ERIC MEYER'S RESET CSS ---------- */
/* ---------- ---------- */

@import url(;

/* ---------- FONTAWESOME ---------- */

[class*="fontawesome-"]:before {
  font-family: 'FontAwesome', sans-serif;

/* ---------- GENERAL ---------- */

body {
    background-color: #C0C0C0;
    color: #000;
    font-family: "Varela Round", Arial, Helvetica, sans-serif;
    font-size: 16px;
    line-height: 1.5em;

input {
    border: none;
    font-family: inherit;
    font-size: inherit;
    font-weight: inherit;
    line-height: inherit;
    -webkit-appearance: none;

/* ---------- LOGIN ---------- */

#login {
    margin: 50px auto;
    width: 400px;

#login h2 {
    background-color: #f95252;
    -webkit-border-radius: 20px 20px 0 0;
    -moz-border-radius: 20px 20px 0 0;
    border-radius: 20px 20px 0 0;
    color: #fff;
    font-size: 28px;
    padding: 20px 26px;

#login h2 span[class*="fontawesome-"] {
    margin-right: 14px;

#login fieldset {
    background-color: #fff;
    -webkit-border-radius: 0 0 20px 20px;
    -moz-border-radius: 0 0 20px 20px;
    border-radius: 0 0 20px 20px;
    padding: 20px 26px;

#login fieldset div {
    color: #777;
    margin-bottom: 14px;

#login fieldset p:last-child {
    margin-bottom: 0;

#login fieldset input {
    -webkit-border-radius: 3px;
    -moz-border-radius: 3px;
    border-radius: 3px;

#login fieldset .error {
    display: block;
     color: #FF1000;
    font-size: 12px;

#login fieldset input[type="email"], #login fieldset input[type="password"] {
    background-color: #eee;
    color: #777;
    padding: 4px 10px;
    width: 328px;

#login fieldset input[type="submit"] {
    background-color: #33cc77;
    color: #fff;
    display: block;
    margin: 0 auto;
    padding: 4px 0;
    width: 100px;

#login fieldset input[type="submit"]:hover {
    background-color: #28ad63;


<div id="login">

<h2><span class="fontawesome-lock"></span>Sign In</h2>

<form action="javascript:void(0);" method="POST">


        <div><label for="email">E-mail address</label></div>
        <div><input type="email" id="email" /></div>

        <div><label for="password">Password</label></div>
        <div><input type="password" id="password" /></div> <!-- JS because of IE support; better: placeholder="Email" -->

        <div><input type="submit" value="Sign In"></div>



And the fiddle: jsfiddle

How to uncheck checked radio button

You might consider adding an additional radio button to each group labeled 'none' or the like. This can create a consistent user experience without complicating the development process.

How to add a button programmatically in VBA next to some sheet cell data?

Suppose your function enters data in columns A and B and you want to a custom Userform to appear if the user selects a cell in column C. One way to do this is to use the SelectionChange event:

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim clickRng As Range
    Dim lastRow As Long

    lastRow = Range("A1").End(xlDown).Row
    Set clickRng = Range("C1:C" & lastRow) //Dynamically set cells that can be clicked based on data in column A

    If Not Intersect(Target, clickRng) Is Nothing Then
        MyUserForm.Show //Launch custom userform
    End If

End Sub

Note that the userform will appear when a user selects any cell in Column C and you might want to populate each cell in Column C with something like "select cell to launch form" to make it obvious that the user needs to perform an action (having a button naturally suggests that it should be clicked)

Replace a character at a specific index in a string?

String are immutable in Java. You can't change them.

You need to create a new string with the character replaced.

String myName = "domanokz";
String newName = myName.substring(0,4)+'x'+myName.substring(5);

Or you can use a StringBuilder:

StringBuilder myName = new StringBuilder("domanokz");
myName.setCharAt(4, 'x');


Regular expression for matching latitude/longitude coordinates?

Whitespace is \s, not \w


See if this works

Unit testing private methods in C#

Ermh... Came along here with exactly the same problem: Test a simple, but pivotal private method. After reading this thread, it appears to be like "I want to drill this simple hole in this simple piece of metal, and I want to make sure the quality meets the specs", and then comes "Okay, this is not to easy. First of all, there is no proper tool to do so, but you could build a gravitational-wave observatory in your garden. Read my article at First, of course, you have to attend some advanced quantum physics courses, then you need tons of ultra-cool nitrogenium, and then, of course, my book available at Amazon"...

In other words...

No, first things first.

Each and every method, may it private, internal, protected, public has to be testable. There has to be a way to implement such tests without such ado as was presented here.

Why? Exactly because of the architectural mentions done so far by some contributors. Perhaps a simple reiteration of software principles may clear up some missunderstandings.

In this case, the usual suspects are: OCP, SRP, and, as always, KIS.

But wait a minute. The idea of making everything publicly available is more of less political and a kind of an attitude. But. When it comes to code, even in then Open Source Community, this is no dogma. Instead, "hiding" something is good practice to make it easier to come familiar with a certain API. You would hide, for example, the very core calculations of your new-to-market digital thermometer building block--not to hide the maths behind the real measured curve to curious code readers, but to prevent your code from becoming dependent on some, perhaps suddenly important users who could not resist using your formerly private, internal, protected code to implement their own ideas.

What am I talking about?

private double TranslateMeasurementIntoLinear(double actualMeasurement);

It's easy to proclaim the Age of Aquarius or what is is been called nowadays, but if my piece of sensor gets from 1.0 to 2.0, the implementation of Translate... might change from a simple linear equation that is easily understandable and "re-usable" for everybody, to a pretty sophisticated calculation that uses analysis or whatever, and so I would break other's code. Why? Because they didn't understand the very priciples of software coding, not even KIS.

To make this fairy tale short: We need a simple way to test private methods--without ado.

First: Happy new year everyone!

Second: Rehearse your architect lessons.

Third: The "public" modifier is religion, not a solution.

C# An established connection was aborted by the software in your host machine

An established connection was aborted by the software in your host machine

That is a boiler-plate error message, it comes out of Windows. The underlying error code is WSAECONNABORTED. Which really doesn't mean more than "connection was aborted". You have to be a bit careful about the "your host machine" part of the phrase. In the vast majority of Windows application programs, it is indeed the host that the desktop app is connected to that aborted the connection. Usually a server somewhere else.

The roles are reversed however when you implement your own server. Now you need to read the error message as "aborted by the application at the other end of the wire". Which is of course not uncommon when you implement a server, client programs that use your server are not unlikely to abort a connection for whatever reason. It can mean that a fire-wall or a proxy terminated the connection but that's not very likely since they typically would not allow the connection to be established in the first place.

You don't really know why a connection was aborted unless you have insight what is going on at the other end of the wire. That's of course hard to come by. If your server is reachable through the Internet then don't discount the possibility that you are being probed by a port scanner. Or your customers, looking for a game cheat.

How to deal with floating point number precision in JavaScript?

The round() function at works nicely:

num = .01 + .06;  // yields 0.0699999999999
rnum = round(num,12); // yields 0.07

I ran into a merge conflict. How can I abort the merge?

If your git version is >= 1.6.1, you can use git reset --merge.

Also, as @Michael Johnson mentions, if your git version is >= 1.7.4, you can also use git merge --abort.

As always, make sure you have no uncommitted changes before you start a merge.

From the git merge man page

git merge --abort is equivalent to git reset --merge when MERGE_HEAD is present.

MERGE_HEAD is present when a merge is in progress.

Also, regarding uncommitted changes when starting a merge:

If you have changes you don't want to commit before starting a merge, just git stash them before the merge and git stash pop after finishing the merge or aborting it.

PermissionError: [WinError 5] Access is denied python using moviepy to write gif

Maybe you wrongly set permission on python3. For instance if for the file permission is set like

`os.chmod('spam.txt', 0777)` --> This will lead to SyntaxError 

This syntax was used in Python2. Now if you change like: os.chmod('spam.txt', 777) --> This is still worst!! Your permission will be set wrongly since are not on "octal" but on decimal.

Afterwards you will get permission Error if you try for instance to remove the file: PermissionError: [WinError 5] Access is denied:

Solution for python3 is quite easy: os.chmod('spam.txt', 0o777) --> The syntax is now ZERO and o "0o"

sqlite database default time value 'now'

i believe you can use


as of version 3.1 (source)

Add property to an array of objects

You can use the forEach method to execute a provided function once for each element in the array. In this provided function you can add the Active property to the element.

Results.forEach(function (element) {
  element.Active = "false";

Best way to work with transactions in MS SQL Server Management Studio

The easisest thing to do is to wrap your code in a transaction, and then execute each batch of T-SQL code line by line.

For example,

Begin Transaction

         -Do some T-SQL queries here.

Rollback transaction -- OR commit transaction

If you want to incorporate error handling you can do so by using a TRY...CATCH BLOCK. Should an error occur you can then rollback the tranasction within the catch block.

For example:

USE AdventureWorks;

    -- Generate a constraint violation error.
    DELETE FROM Production.Product
    WHERE ProductID = 980;
        ERROR_NUMBER() AS ErrorNumber
        ,ERROR_SEVERITY() AS ErrorSeverity
        ,ERROR_STATE() AS ErrorState
        ,ERROR_PROCEDURE() AS ErrorProcedure
        ,ERROR_LINE() AS ErrorLine
        ,ERROR_MESSAGE() AS ErrorMessage;

    IF @@TRANCOUNT > 0


See the following link for more details.

Hope this helps but please let me know if you need more details.

Edit In Place Content Editing

I've modified your plunker to get it working via angular-xeditable:

It is common solution for inline editing - you creale hyperlinks with editable-text directive that toggles into <input type="text"> tag:

<a href="#" editable-text="" ng-click="myform.$show()" e-placeholder="Name">
    {{ || 'empty'}}

For date I used editable-date directive that toggles into html5 <input type="date">.

CSS/Javascript to force html table row on a single line


td, th {
  white-space: nowrap;
  overflow: hidden;

how to Call super constructor in Lombok

Version 1.18 of Lombok introduced the @SuperBuilder annotation. We can use this to solve our problem in a simpler way.

You can refer to

so in your child class, you will need these annotations:

@EqualsAndHashCode(callSuper = true)

in your parent class:


How can I copy the output of a command directly into my clipboard?

I've created a tool for Linux/OSX/Cygwin that is similar to some of these others but slightly unique. I call it cb and it can be found in this github gist.

In that gist I demonstrate how to do copy and paste via commandline using Linux, macOS, and Cygwin.


    cat | xclip -selection clipboard

    xclip -selection clipboard -o


    cat | pbcopy



    cat > /dev/clipboard

    cat /dev/clipboard

Note: I originally just intended to mention this in my comment to Bob Enohp's answer. But then I realized that I should add a README to my gist. Since the gist editor doesn't offer a Markdown preview I used the answer box here and after copy/pasting it to my gist thought, "I might as well submit the answer."


A leak-proof tee to the clipboard

This script is modeled after tee (see man tee).

It's like your normal copy and paste commands, but unified and able to sense when you want it to be chainable



$ date | cb
# clipboard contains: Tue Jan 24 23:00:00 EST 2017


# clipboard retained from the previous block
$ cb
Tue Jan 24 23:00:00 EST 2017
$ cb | cat
Tue Jan 24 23:00:00 EST 2017
$ cb > foo
$ cat foo
Tue Jan 24 23:00:00 EST 2017


$ date | cb | tee updates.log
Tue Jan 24 23:11:11 EST 2017
$ cat updates.log
Tue Jan 24 23:11:11 EST 2017
# clipboard contains: Tue Jan 24 23:11:11 EST 2017

Copy via file redirect

(chronologically it made sense to demo this at the end)

# clipboard retained from the previous block
$ cb < foo
$ cb
Tue Jan 24 23:00:00 EST 2017
# note the minutes and seconds changed from 11 back to 00

Prime numbers between 1 to 100 in C Programming Language

#include <stdio.h>
#include <conio.h>
int main()
    int i,j;
    int b=0;
    for (i=2;i<=100;i++){
        for (j=2;j<=i;j++){
            if (i%j==0){
        if (i==j)
            print f("\n%d",j);
    getch ();

How to open maximized window with Javascript?

If I use Firefox then screen.width and screen.height works fine but in IE and Chrome they don't work properly instead it opens with the minimum size.

And yes I tried giving too large numbers too like 10000 for both height and width but not exactly the maximized effect.

ASP.NET email validator regex

Here is the regex for the Internet Email Address using the RegularExpressionValidator in .NET


By the way if you put a RegularExpressionValidator on the page and go to the design view there is a ValidationExpression field that you can use to choose from a list of expressions provided by .NET. Once you choose the expression you want there is a Validation expression: textbox that holds the regex used for the validator

Find and replace with sed in directory and sub directories

In linuxOS:

sed -i 's/textSerch/textReplace/g' namefile

if "sed" not work try :

perl -i -pe 's/textSerch/textReplace/g' namefile

tSQL - Conversion from varchar to numeric works for all but integer

Actually whether there are digits or not is irrelevant. The . (dot) is forbidden if you want to cast to int. Dot can't - logically - be part of Integer definition, so even:

select cast ('7.0' as int)
select cast ('7.' as int)

will fail but both are fine for floats.

How to tell PowerShell to wait for each command to end before starting the next?

Besides using Start-Process -Wait, piping the output of an executable will make Powershell wait. Depending on the need, I will typically pipe to Out-Null, Out-Default, Out-String or Out-String -Stream. Here is a long list of some other output options.

# Saving output as a string to a variable.
$output = ping.exe | Out-String

# Filtering the output.
ping | where { $_ -match '^reply' }

# Using Start-Process affords the most control.
Start-Process -Wait

I do miss the CMD/Bash style operators that you referenced (&, &&, ||). It seems we have to be more verbose with Powershell.

Real time data graphing on a line chart with html5

Here's a gist I discovered for real-time charts in ChartJS:

ChartJS looks like it's simple to use and looks nice.

Also there's FusionCharts, a more sophisticated library for enterprise use, with a demo of real time here:

EDIT I also started using Rickshaw for real time graphs and it's easy to use and pretty customizable:

Backbone.js fetch with parameters

You can also set processData to true:

    data: { page: 1 },
    processData: true

Jquery will auto process data object into param string,

but in Backbone.sync function, Backbone turn the processData off because Backbone will use other method to process data in POST,UPDATE...

in Backbone source:

if (params.type !== 'GET' && !Backbone.emulateJSON) {
    params.processData = false;

How to automatically start a service when running a docker container?

docker export -o <nameOfContainer>.tar <nameOfContainer>

Might need to prune the existing container using docker prune ...

Import with required modifications:

cat <nameOfContainer>.tar | docker import -c "ENTRYPOINT service mysql start && /bin/bash" - <nameOfContainer>

Run the container for example with always restart option to make sure it will auto resume after host/daemon recycle:

docker run -d -t -i --restart always --name <nameOfContainer> <nameOfContainer> /bin/bash

Side note: In my opinion reasonable is to start only cron service leaving container as clean as possible then just modify crontab or cron.hourly, .daily etc... with corresponding checkup/monitoring scripts. Reason is You rely only on one daemon and in case of changes it is easier with ansible or puppet to redistribute cron scripts instead of track services that start at boot.

how to update the multiple rows at a time using linq to sql?

Do not use the ToList() method as in the accepted answer !

Running SQL profiler, I verified and found that ToList() function gets all the records from the database. It is really bad performance !!

I would have run this query by pure sql command as follows:

string query = "Update YourTable Set ... Where ...";    
context.Database.ExecuteSqlCommandAsync(query, new SqlParameter("@ColumnY", value1), new SqlParameter("@ColumnZ", value2));

This would operate the update in one-shot without selecting even one row.

Removing white space around a saved image in matplotlib

The following function incorporates johannes-s answer above. I have tested it with plt.figure and plt.subplots() with multiple axes, and it works nicely.

def save(filepath, fig=None):
    '''Save the current image with no whitespace
    Example filepath: "myfig.png" or r"C:\myfig.pdf" 
    import matplotlib.pyplot as plt
    if not fig:
        fig = plt.gcf()

    for ax in fig.axes:
    fig.savefig(filepath, pad_inches = 0, bbox_inches='tight')

Autocompletion in Vim

You can use a plugin like AutoComplPop to get automatic code completion as you type.

2015 Edit: I personally use YouCompleteMe now.

Forgot Oracle username and password, how to retrieve?

  1. Open Command Prompt/Terminal and type:

    sqlplus / as SYSDBA

  2. SQL prompt will turn up. Now type:

    ALTER USER existing_account_name IDENTIFIED BY new_password ACCOUNT UNLOCK;

  3. Voila! You've unlocked your account.

Jquery - How to get the style display attribute "none / block"

You could try:


What to do with commit made in a detached head

You can just do git merge <commit-number> or git cherry-pick <commit> <commit> ...

As suggested by Ryan Stewart you may also create a branch from the current HEAD:

git branch brand-name

Or just a tag:

git tag tag-name

Show a leading zero if a number is less than 10

There's no built-in JavaScript function to do this, but you can write your own fairly easily:

function pad(n) {
    return (n < 10) ? ("0" + n) : n;


Meanwhile there is a native JS function that does that. See String#padStart

console.log(String(5).padStart(2, '0'));

Replace preg_replace() e modifier with preg_replace_callback

You shouldn't use flag e (or eval in general).

You can also use T-Regx library


What is the effect of extern "C" in C++?

In every C++ program, all non-static functions are represented in the binary file as symbols. These symbols are special text strings that uniquely identify a function in the program.

In C, the symbol name is the same as the function name. This is possible because in C no two non-static functions can have the same name.

Because C++ allows overloading and has many features that C does not — like classes, member functions, exception specifications - it is not possible to simply use the function name as the symbol name. To solve that, C++ uses so-called name mangling, which transforms the function name and all the necessary information (like the number and size of the arguments) into some weird-looking string processed only by the compiler and linker.

So if you specify a function to be extern C, the compiler doesn't performs name mangling with it and it can be directly accessed using its symbol name as the function name.

This comes handy while using dlsym() and dlopen() for calling such functions.

C default arguments

I improved Jens Gustedt’s answer so that:

  1. inline functions aren’t employed
  2. defaults are computed during preprocessing
  3. modular reuseable macros
  4. possible to set compiler error that meaningfully matches the case of insufficient arguments for the allowed defaults
  5. the defaults aren’t required to form the tail of the parameter list if the argument types will remain unambiguous
  6. interopts with C11 _Generic
  7. vary the function name by the number of arguments!


#ifndef VARIADIC

#define _NARG2(_0, _1, _2, ...) _2
#define NUMARG2(...) _NARG2(__VA_ARGS__, 2, 1, 0)
#define _NARG3(_0, _1, _2, _3, ...) _3
#define NUMARG3(...) _NARG3(__VA_ARGS__, 3, 2, 1, 0)
#define _NARG4(_0, _1, _2, _3, _4, ...) _4
#define NUMARG4(...) _NARG4(__VA_ARGS__, 4, 3, 2, 1, 0)
#define _NARG5(_0, _1, _2, _3, _4, _5, ...) _5
#define NUMARG5(...) _NARG5(__VA_ARGS__, 5, 4, 3, 2, 1, 0)
#define _NARG6(_0, _1, _2, _3, _4, _5, _6, ...) _6
#define NUMARG6(...) _NARG6(__VA_ARGS__, 6, 5, 4, 3, 2, 1, 0)
#define _NARG7(_0, _1, _2, _3, _4, _5, _6, _7, ...) _7
#define NUMARG7(...) _NARG7(__VA_ARGS__, 7, 6, 5, 4, 3, 2, 1, 0)
#define _NARG8(_0, _1, _2, _3, _4, _5, _6, _7, _8, ...) _8
#define NUMARG8(...) _NARG8(__VA_ARGS__, 8, 7, 6, 5, 4, 3, 2, 1, 0)
#define _NARG9(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, ...) _9
#define NUMARG9(...) _NARG9(__VA_ARGS__, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
#define __VARIADIC(name, num_args, ...) name ## _ ## num_args (__VA_ARGS__)
#define _VARIADIC(name, num_args, ...) name (__VARIADIC(name, num_args, __VA_ARGS__))
#define VARIADIC(name, num_args, ...) _VARIADIC(name, num_args, __VA_ARGS__)
#define VARIADIC2(name, num_args, ...) __VARIADIC(name, num_args, __VA_ARGS__)

// Vary function name by number of arguments supplied
#define VARIADIC_NAME(name, num_args) name ## _ ## num_args ## _name ()
#define NVARIADIC(name, num_args, ...) _VARIADIC(VARIADIC_NAME(name, num_args), num_args, __VA_ARGS__)


Simplified usage scenario:

const uint32*
uint32_frombytes(uint32* out, const uint8* in, size_t bytes);

The output buffer defaults to NULL if not provided.

#include "variadic.h"

#define uint32_frombytes_2(   b, c) NULL, b, c
#define uint32_frombytes_3(a, b, c)    a, b, c
#define uint32_frombytes(...) VARIADIC(uint32_frombytes, NUMARG3(__VA_ARGS__), __VA_ARGS__)

And with _Generic:

const uint8*
uint16_tobytes(const uint16* in, uint8* out, size_t bytes);

const uint16*
uint16_frombytes(uint16* out, const uint8* in, size_t bytes);

const uint8*
uint32_tobytes(const uint32* in, uint8* out, size_t bytes);

const uint32*
uint32_frombytes(uint32* out, const uint8* in, size_t bytes);

The output buffer defaults to NULL if not provided.
Generic function name supported on the non-uint8 type, except where said type
is unavailable because the argument for output buffer was not provided.

#include "variadic.h"

#define   uint16_tobytes_2(a,    c) a, NULL, c
#define   uint16_tobytes_3(a, b, c) a,    b, c
#define   uint16_tobytes(...) VARIADIC(  uint16_tobytes, NUMARG3(__VA_ARGS__), __VA_ARGS__)

#define uint16_frombytes_2(   b, c) NULL, b, c
#define uint16_frombytes_3(a, b, c)    a, b, c
#define uint16_frombytes(...) VARIADIC(uint16_frombytes, NUMARG3(__VA_ARGS__), __VA_ARGS__)

#define   uint32_tobytes_2(a,    c) a, NULL, c
#define   uint32_tobytes_3(a, b, c) a,    b, c
#define   uint32_tobytes(...) VARIADIC(  uint32_tobytes, NUMARG3(__VA_ARGS__), __VA_ARGS__)

#define uint32_frombytes_2(   b, c) NULL, b, c
#define uint32_frombytes_3(a, b, c)    a, b, c
#define uint32_frombytes(...) VARIADIC(uint32_frombytes, NUMARG3(__VA_ARGS__), __VA_ARGS__)

#define   tobytes(a, ...) _Generic((a),                                                                                                 \
                                   const uint16*: uint16_tobytes,                                                                       \
                                   const uint32*: uint32_tobytes)  (VARIADIC2(  uint32_tobytes, NUMARG3(a, __VA_ARGS__), a, __VA_ARGS__))

#define frombytes(a, ...) _Generic((a),                                                                                                 \
                                         uint16*: uint16_frombytes,                                                                     \
                                         uint32*: uint32_frombytes)(VARIADIC2(uint32_frombytes, NUMARG3(a, __VA_ARGS__), a, __VA_ARGS__))

And with variadic function name selection, which can't be combined with _Generic:

// winternitz() with 5 arguments is replaced with merkle_lamport() on those 5 arguments.

#define   merkle_lamport_5(a, b, c, d, e) a, b, c, d, e
#define   winternitz_7(a, b, c, d, e, f, g) a, b, c, d, e, f, g
#define   winternitz_5_name() merkle_lamport
#define   winternitz_7_name() winternitz
#define   winternitz(...) NVARIADIC(winternitz, NUMARG7(__VA_ARGS__), __VA_ARGS__)

How to fix "could not find a base address that matches schema http"... in WCF

Confirmed my fix:

In your web.config file you should configure it to look as such:

<system.serviceModel >
    <serviceHostingEnvironment configSource=".\Configurations\ServiceHosting.config" />

Then, build a folder structure that looks like this:


The base serviceHosting.config should look like this:

<?xml version="1.0"?>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true">

while the one in /Deploy looks like this:

<serviceHostingEnvironment aspNetCompatibilityEnabled="true">
        <add prefix=""/>

Beyond this, you need to add a manual or automated deployment step to copy the file from /Deploy overtop the one in /Configurations. This works incredibly well for service address and connection strings, and saves effort doing other workarounds.

If you don't like this approach (which scales well to farms, but is weaker on single machine), you might consider adding a web.config file a level up from the service deployment on the host's machine and put the serviceHostingEnvironment node there. It should cascade for you.

How is the java memory pool divided?

Java Heap Memory is part of memory allocated to JVM by Operating System.

Objects reside in an area called the heap. The heap is created when the JVM starts up and may increase or decrease in size while the application runs. When the heap becomes full, garbage is collected.

enter image description here

You can find more details about Eden Space, Survivor Space, Tenured Space and Permanent Generation in below SE question:

Young , Tenured and Perm generation

PermGen has been replaced with Metaspace since Java 8 release.

Regarding your queries:

  1. Eden Space, Survivor Space, Tenured Space are part of heap memory
  2. Metaspace and Code Cache are part of non-heap memory.

Codecache: The Java Virtual Machine (JVM) generates native code and stores it in a memory area called the codecache. The JVM generates native code for a variety of reasons, including for the dynamically generated interpreter loop, Java Native Interface (JNI) stubs, and for Java methods that are compiled into native code by the just-in-time (JIT) compiler. The JIT is by far the biggest user of the codecache.

Apache - MySQL Service detected with wrong path. / Ports already in use

its because you probaly installed wamp server and uninstall it but wampmysql.exe still running and using the default mysql port go to msconfig under services tab uncheck wampmysqld to deactivate it reboot the computer should work

How to limit google autocomplete results to City and Country only

Also you will need to zoom and center the map due to your country restrictions!

Just use zoom and center parameters! ;)

function initialize() {
  var myOptions = {
    zoom: countries['us'].zoom,
    center: countries['us'].center,
    mapTypeControl: false,
    panControl: false,
    zoomControl: false,
    streetViewControl: false

  ... all other code ...


How do I import a .dmp file into Oracle?

.dmp files are dumps of oracle databases created with the "exp" command. You can import them using the "imp" command.

If you have an oracle client intalled on your machine, you can executed the command

imp help=y

to find out how it works. What will definitely help is knowing from wich schema the data was exported and what the oracle version was.

What is the difference between tinyint, smallint, mediumint, bigint and int in MySQL?

They take up different amounts of space and they have different ranges of acceptable values.

Here are the sizes and ranges of values for SQL Server, other RDBMSes have similar documentation:

Turns out they all use the same specification (with a few minor exceptions noted below) but support various combinations of those types (Oracle not included because it has just a NUMBER datatype, see the above link):

             | SQL Server    MySQL   Postgres    DB2
tinyint      |     X           X                
smallint     |     X           X         X        X
mediumint    |                 X
int/integer  |     X           X         X        X 
bigint       |     X           X         X        X

And they support the same value ranges (with one exception below) and all have the same storage requirements:

            | Bytes    Range (signed)                               Range (unsigned)
tinyint     | 1 byte   -128 to 127                                  0 to 255
smallint    | 2 bytes  -32768 to 32767                              0 to 65535
mediumint   | 3 bytes  -8388608 to 8388607                          0 to 16777215
int/integer | 4 bytes  -2147483648 to 2147483647                    0 to 4294967295
bigint      | 8 bytes  -9223372036854775808 to 9223372036854775807  0 to 18446744073709551615 

The "unsigned" types are only available in MySQL, and the rest just use the signed ranges, with one notable exception: tinyint in SQL Server is unsigned and has a value range of 0 to 255

How can I get the IP address from NIC in Python?

Yet another way of obtaining the IP Address from a NIC, using Python.

I had this as part of an app that I developed long time ago, and I didn't wanted to simply git rm So, here I provide the approach, using subprocess and list comprehensions for the sake of functional approach and less lines of code:

import subprocess as sp

__version__ = "v1.0"                                                            
__author__ = "@ivanleoncz"

def get_nic_ipv4(nic):                                                          
        Get IP address from a NIC.                                              

        nic : str
            Network Interface Card used for the query.                          

        ipaddr : str
            Ipaddress from the NIC provided as parameter.                       
    result = None                                                               
        result = sp.check_output(["ip", "-4", "addr", "show", nic],             
    except Exception:
        return "Unkown NIC: %s" % nic
    result = result.decode().splitlines()
    ipaddr = [l.split()[1].split('/')[0] for l in result if "inet" in l]        
    return ipaddr[0]

Additionally, you can use a similar approach for obtaining a list of NICs:

def get_nics():                                                                 
        Get all NICs from the Operating System.                                 

        nics : list                                                             
            All Network Interface Cards.                                        
    result = sp.check_output(["ip", "addr", "show"])                            
    result = result.decode().splitlines()                                       
    nics = [l.split()[1].strip(':') for l in result if l[0].isdigit()]          
    return nics                                                

Here's the solution as a Gist.

And you would have something like this:

$ python3
Python 3.6.7 (default, Oct 22 2018, 11:32:17) 
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import helpers
>>> helpers.get_nics()
['lo', 'enp1s0', 'wlp2s0', 'docker0']
>>> helpers.get_nic_ipv4('docker0')
>>> helpers.get_nic_ipv4('docker2')
'Unkown NIC: docker2'

IIS: Where can I find the IIS logs?

I have found the IIS Log files at the following location.


which help to fix my issue.

Deck of cards JAVA

First you have an architectural issue with your classes. You moved the property deck inside your class Card. But of couse it is a property of the card deck and thus has to be inside class DeckOfCards. The initialization loop should then not be in the constructor of Card but of your deck class. Moreover, the deck is an array of int at the moment but should be an array of Cards.

Second, inside method Deal you should refer to suits as Card.suits and make this member static final. Same for ranks.

And last, please stick to naming conventions. Method names are always starting with a lower case letter, i.e. shuffle instead of Shuffle.

Java switch statement: Constant expression required, but it IS constant

I recommend using the following way:

public enum Animal {
    DOG("dog"), TIGER("tiger"), LION("lion");
    private final String name;

    public String toString() {

public class DemoSwitchUsage {

     private String getAnimal(String name) {
         Animal animalName = Animal.valueOf(name);
         switch(animalName) {
         case DOG:
             // write the code required.
         case LION:
             // Write the code required.

EditText request focus

Yes, I got the answer.. just simply edit the manifest file as:

        <activity android:name=".MainActivity"
        android:windowSoftInputMode="stateAlwaysVisible" />

and set EditText.requestFocus() in onCreate()..


Why rgb and not cmy?

This is nothing to do with hardware nor software. Simply that RGB are the 3 primary colours which can be combined in various ways to produce every other colour. It is more about the human convention/perception of colours which carried over.

You may find this article interesting.

Error parsing yaml file: mapping values are not allowed here

Another cause is wrong indentation which means trying to create the wrong objects. I've just fixed one in a Kubernetes Ingress definition:


- path: / 
      serviceName: <service_name> 
      servicePort: <port> 


- path: /
    serviceName: <service_name>
    servicePort: <port>

Angular bootstrap datepicker date format does not format ng-model value

Defining a new directive to work around a bug is not really ideal.

Because the datepicker displays later dates correctly, one simple workaround could be just setting the model variable to null first, and then to the current date after a while:

$scope.dt = null;
$timeout( function(){
    $scope.dt = new Date();

Cannot declare instance members in a static class in C#

It is not legal to declare an instance member in a static class. Static class's cannot be instantiated hence it makes no sense to have an instance members (they'd never be accessible).

XPath to select multiple tags

You can avoid the repetition with an attribute test instead:

a/b/*[local-name()='c' or local-name()='d' or local-name()='e']

Contrary to Dimitre's antagonistic opinion, the above is not incorrect in a vacuum where the OP has not specified the interaction with namespaces. The self:: axis is namespace restrictive, local-name() is not. If the OP's intention is to capture c|d|e regardless of namespace (which I'd suggest is even a likely scenario given the OR nature of the problem) then it is "another answer that still has some positive votes" which is incorrect.

You can't be definitive without definition, though I'm quite happy to delete my answer as genuinely incorrect if the OP clarifies his question such that I am incorrect.

How can I define a composite primary key in SQL?

In Oracle database we can achieve like this.

  StudentID Number(38, 0) not null,
  DepartmentID Number(38, 0) not null,
  PRIMARY KEY (StudentID, DepartmentID)

How to check if a number is between two values?

this is a generic method, you can use everywhere

const isBetween = (num1,num2,value) => value > num1 && value < num2 

How does one Display a Hyperlink in React Native App?

Just thought I'd share my hacky solution with anyone who's discovering this problem now with embedded links within a string. It attempts to inline the links by rendering it dynamically with what ever string is fed into it.

Please feel free to tweak it to your needs. It's working for our purposes as such:

This is an example of how would appear.

View it on Gist:

import React from 'react';
import { Linking, Text } from 'react-native';

export default function renderHyperlinkedText(string, baseStyles = {}, linkStyles = {}, openLink) {
  if (typeof string !== 'string') return null;
  const httpRegex = /http/g;
  const wwwRegex = /www/g;
  const comRegex = /.com/g;
  const httpType = httpRegex.test(string);
  const wwwType = wwwRegex.test(string);
  const comIndices = getMatchedIndices(comRegex, string);
  if ((httpType || wwwType) && comIndices.length) {
    // Reset these regex indices because `comRegex` throws it off at its completion. 
    httpRegex.lastIndex = 0;
    wwwRegex.lastIndex = 0;
    const httpIndices = httpType ? 
      getMatchedIndices(httpRegex, string) : getMatchedIndices(wwwRegex, string);
    if (httpIndices.length === comIndices.length) {
      const result = [];
      let noLinkString = string.substring(0, httpIndices[0] || string.length);
      result.push(<Text key={noLinkString} style={baseStyles}>{ noLinkString }</Text>);
      for (let i = 0; i < httpIndices.length; i += 1) {
        const linkString = string.substring(httpIndices[i], comIndices[i] + 4);
            style={[baseStyles, linkStyles]}
            onPress={openLink ? () => openLink(linkString) : () => Linking.openURL(linkString)}
            { linkString }
        noLinkString = string.substring(comIndices[i] + 4, httpIndices[i + 1] || string.length);
        if (noLinkString) {
            <Text key={noLinkString} style={baseStyles}>
              { noLinkString }
      // Make sure the parent `<View>` container has a style of `flexWrap: 'wrap'`
      return result;
  return <Text style={baseStyles}>{ string }</Text>;

function getMatchedIndices(regex, text) {
  const result = [];
  let match;
  do {
    match = regex.exec(text);
    if (match) result.push(match.index);
  } while (match);
  return result;

How to add dll in c# project

Have you added the dll into your project references list? If not right click on the project "References" folder and selecet "Add Reference" then use browse to locate your science.dll, select it and click ok.


I can't see the image of your VS instance that some people are referring to and I note that you now say that it works in Net4.0 and VS2010.

VS2008 projects support NET 3.5 by default. I expect that is the problem as your DLL may be NET 4.0 compliant but not NET 3.5.

What's the difference between next() and nextLine() methods from Scanner class?

next() and nextLine() methods are associated with Scanner and is used for getting String inputs. Their differences are...

next() can read the input only till the space. It can't read two words separated by space. Also, next() places the cursor in the same line after reading the input.

nextLine() reads input including space between the words (that is, it reads till the end of line \n). Once the input is read, nextLine() positions the cursor in the next line.

import java.util.Scanner;

public class temp
    public static void main(String arg[])
        Scanner sc=new Scanner(;
        System.out.println("enter string for c");
        System.out.println("c is "+c);
        System.out.println("enter string for d");
        System.out.println("d is "+d);


enter string for c abc def
c is abc

enter string for d

d is def

If you use nextLine() instead of next() then


enter string for c

c is ABC DEF
enter string for d

d is GHI

How to validate an email address in PHP


Nowadays, if you use a HTML5 form with type=email then you're already by 80% safe since browser engines have their own validator. To complement it, add this regex to your preg_match_all() and negate it:

if (!preg_match_all("/(?![[:alnum:]]|@|-|_|\.)./",$email)) { .. }

Find the regex used by HTML5 forms for validation

How can I see function arguments in IPython Notebook Server 3?

Shift-Tab works for me to view the dcoumentation

How to change values in a tuple?

I believe this technically answers the question, but don't do this at home. At the moment, all answers involve creating a new tuple, but you can use ctypes to modify a tuple in-memory. Relying on various implementation details of CPython on a 64-bit system, one way to do this is as follows:

def modify_tuple(t, idx, new_value):
    # `id` happens to give the memory address in CPython; you may
    # want to use `ctypes.addressof` instead.
    element_ptr = (ctypes.c_longlong).from_address(id(t) + (3 + idx)*8)
    element_ptr.value = id(new_value)
    # Manually increment the reference count to `new_value` to pretend that
    # this is not a terrible idea.
    ref_count = (ctypes.c_longlong).from_address(id(new_value))
    ref_count.value += 1

t = (10, 20, 30)
modify_tuple(t, 1, 50)   # t is now (10, 50, 30)
modify_tuple(t, -1, 50)  # Will probably crash your Python runtime

A valid provisioning profile for this executable was not found... (again)

Xcode5 has broken this again (congratulations to Apple for failing to bother testing one of their buggiest bits of code. Again).

A new way to break/fix it:

If you have:

  1. An old profile on your device (team profile, or non-team profile)
  2. A new profile generated automatically on the App Store, by any copy of Xcode5, even if it's simply an update to the profile you already had
  3. (NB: if any colleague adds themself to the profile, this triggers the above "change")
  4. You use the new "Accounts" dialog to download profiles (NB: this is now REQUIRED by Apple for various situations - all other approaches, including manual download, appear to be unsupported. Even though the Apple Developer site TELLS YOU TO MANUALLY DOWNLOAD! Don't do it! It breaks Xcode5!)
  5. Xcode5 will INCORRECTLY hide AND RENAME that profile in the drop-down selector in Build Settings
  6. (I detest this drop-down. Some idiot at Apple keeps removing information from it, and someone else keeps adding it back, it flip-flops between Xcode point releases. WHY??!?!)
  7. There is NO WAY you can select the correct profile - whatever you select, Xcode5 will use the wrong one

The solution is easy enough. The "Apple engineering are lazy" solution:

  1. Go to Xcode5 -> Window -> Organizer -> Devices
  2. Select your device
  3. Select provisioning profiles
  4. Delete everything relating to your current project and/or Team (even other projects, if necessary - they can all be downloaded later if still needed!)
  5. Re-build.
  6. You should get an error from Xcode5 that the profile doesn't exist. Even though you manually had seleted the profile that was ALREADY PRESENT on your machine (yep - that dropdown is buggy again. It lies about the profile it selects behind the scenes!)
  7. In the profile selector, select the "real" profile
  8. Build, run - success!

How to empty a redis database?

Be careful here.

FlushDB deletes all keys in the current database while FlushALL deletes all keys in all databases on the current host.

Resolving require paths with webpack

For future reference, webpack 2 removed everything but modules as a way to resolve paths. This means root will not work.

The example configuration starts with:

  modules: [path.resolve(__dirname, "app"), "node_modules"]
  // (was split into `root`, `modulesDirectories` and `fallback` in the old options)

How to display two digits after decimal point in SQL Server

You can also Make use of the Following if you want to Cast and Round as well. That may help you or someone else.

SELECT CAST(ROUND(Column_Name, 2) AS DECIMAL(10,2), Name FROM Table_Name

How to add url parameters to Django template url tag?


            {% for ticket in tickets %}
                <td class="ticket_id">{{}}</td>
                <td class="ticket_eam">{{ticket.eam}}</td>
                <td class="ticket_subject">{{ticket.subject}}</td>
                <td><a href="{% url 'ticket_details' %}"><button data-toggle="modal" data-target="#modaldemo3" class="value-modal"><i class="icon ion-edit"></a></i></button> <button><i class="fa fa-eye-slash"></i></button>
            {% endfor %}

The {% url 'ticket_details' %} is the function name in your views


def ticket_details(request, ticket_id):

   return render(request, ticket.html)

ticket_id is the parameter you will get from the


urlpatterns = [
path('ticket_details/?P<int:ticket_id>/', views.ticket_details, name="ticket_details") ]

/?P - where ticket_id is the name of the group and pattern is some pattern to match.

MS Access DB Engine (32-bit) with Office 64-bit

Here's a workaround for installing the 64-bit version of the Microsoft Access Database Engine 2010 redistributable on a system with a 32-bit MS Office version installed:

  • Check the 64-bit registry key "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\14.0\Common\FilesPaths" before installing the 64-bit version of the Microsoft Access Database Engine 2010 redistributable.
  • If it does not contain the "mso.dll" registry value, then you will need to rename or delete the value after installing the 64-bit version of the Microsoft Access Database Engine 2010 redistributable on a system with a 32-bit version of MS Office installed.
  • Use the "/passive" command line parameter to install the redistributable, e.g. "C:\directory path\AccessDatabaseEngine_x64.exe" /passive
  • Delete or rename the "mso.dll" registry value, which contains the path to the 64-bit version of MSO.DLL (and should not be used by 32-bit MS Office versions).

Now you can start a 32-bit MS Office application without the "re-configuring" issue. Note that the "mso.dll" registry value will already be present if a 64-bit version of MS Office is installed. In this case the value should not be deleted or renamed.

Also if you do not want to use the "/passive" command line parameter you can edit the AceRedist.msi file to remove the MS Office architecture check:

You can now use this file to install the Microsoft Access Database Engine 2010 redistributable on a system where a "conflicting" version of MS Office is installed (e.g. 64-bit version on system with 32-bit MS Office version) Make sure that you rename the "mso.dll" registry value as explained above (if needed).

Why do I get a "permission denied" error while installing a gem?

I had the same problem using rvm on Ubuntu, was fixed by setting the source on my terminal as a short-term solution:

source $HOME/.rvm/scripts/rvm


source /home/$USER/.rvm/scripts/rvm

and configure a default Ruby Version, 2.3.3 in my case.

rvm use 2.3.3 --default

And a long-term Solution is to add your source to your .bashrc file to permanently make Ubuntu look in .rvm for all the Ruby files.


source .rvm/scripts/rvm


$HOME/.bashrc file.

Finding square root without using sqrt function?

//long division method.
using namespace std;
int main() {
int n, i = 1, divisor, dividend, j = 1, digit;
cin >> n;
while (i * i < n) {
    i = i + 1;
i = i - 1;
cout << i << '.';

divisor  = 2 * i;
dividend = n - (i * i );
while( j <= 5) {
    dividend = dividend * 100;
    digit = 0;
    while ((divisor * 10 + digit) * digit < dividend) {
        digit = digit + 1;
    digit = digit  - 1;
    cout << digit;
    dividend = dividend - ((divisor * 10 + digit) * digit);
    divisor = divisor * 10 + 2*digit;
    j = j + 1;
cout << endl;
return 0;

Stored Procedure parameter default value - is this a constant or a variable

It has to be a constant - the value has to be computable at the time that the procedure is created, and that one computation has to provide the value that will always be used.

Look at the definition of sys.all_parameters:

default_value sql_variant If has_default_value is 1, the value of this column is the value of the default for the parameter; otherwise, NULL.

That is, whatever the default for a parameter is, it has to fit in that column.

As Alex K pointed out in the comments, you can just do:

CREATE PROCEDURE [dbo].[problemParam] 
    @StartDate INT = NULL,
    @EndDate INT = NULL
   SET @StartDate = COALESCE(@StartDate,CONVERT(INT,(CONVERT(CHAR(8),GETDATE()-130,112))))

provided that NULL isn't intended to be a valid value for @StartDate.

As to the blog post you linked to in the comments - that's talking about a very specific context - that, the result of evaluating GETDATE() within the context of a single query is often considered to be constant. I don't know of many people (unlike the blog author) who would consider a separate expression inside a UDF to be part of the same query as the query that calls the UDF.

How to enumerate a range of numbers starting at 1

>>> list(enumerate(range(1999, 2005)))[1:]
[(1, 2000), (2, 2001), (3, 2002), (4, 2003), (5, 2004)]

How to select rows with NaN in particular column?

Try the following:


Convert datetime to valid JavaScript date

Just use Date.parse() which returns a Number, then use new Date() to parse it:

var thedate = new Date(Date.parse("2011-07-14 11:23:00"));

Keyboard shortcut to comment lines in Sublime Text 3

You can add the following lines to Preferences / Key Bindings - User:

{ "keys": ["control+keypad_divide"],"command": "toggle_comment", "args": {"block": false} }, 
{ "keys": ["shift+control+keypad_divide"],"command": "toggle_comment", "args": {"block": true}}

This is how I sorted the problem out - replacing "ctrl" with "control" and "/" with "keypad_divide".

[] and {} vs list() and dict(), which is better?

In my opinion [] and {} are the most pythonic and readable ways to create empty lists/dicts.

Be wary of set()'s though, for example:

this_set = {5}
some_other_set = {}

Can be confusing. The first creates a set with one element, the second creates an empty dict and not a set.

Flatten list of lists

Flatten the list to "remove the brackets" using a nested list comprehension. This will un-nest each list stored in your list of lists!

list_of_lists = [[180.0], [173.8], [164.2], [156.5], [147.2], [138.2]]
flattened = [val for sublist in list_of_lists for val in sublist]

Nested list comprehensions evaluate in the same manner that they unwrap (i.e. add newline and tab for each new loop. So in this case:

flattened = [val for sublist in list_of_lists for val in sublist]

is equivalent to:

flattened = []
for sublist in list_of_lists:
    for val in sublist:

The big difference is that the list comp evaluates MUCH faster than the unraveled loop and eliminates the append calls!

If you have multiple items in a sublist the list comp will even flatten that. ie

>>> list_of_lists = [[180.0, 1, 2, 3], [173.8], [164.2], [156.5], [147.2], [138.2]]
>>> flattened  = [val for sublist in list_of_lists for val in sublist]
>>> flattened 
[180.0, 1, 2, 3, 173.8, 164.2, 156.5, 147.2,138.2]

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

[SOLVED] Neos/swiftmailer: Address in mailbox given [] does not comply with RFC 2822, 3.6.2

Exception in line 261 of /var/www/html/vendor/Packages/Libraries/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/MailboxHeader.php: Address in mailbox given [] does not comply with RFC 2822, 3.6.2.

private function _assertValidAddress($address)
    if (!preg_match('/^'.$this->getGrammar()->getDefinition('addr-spec').'$/D',
        $address)) {
        throw new Swift_RfcComplianceException(
            'Address in mailbox given ['.$address.
            '] does not comply with RFC 2822, 3.6.2.'

Saving ssh key fails

For Linux on terminal use:

ssh-keygen -t ed25519 -C "<comment>"

this generate new modeled key. Or can create as:

ssh-keygen -t rsa -b 2048 -C "any comment"

Then continue following terminal.. give any name to the file as asked Again follow it with empty passphrase..and continue

Then goto the /home/user/.ssh/id_ed25519 or /home/user/.ssh/id_rsa (is hidden file..look by doing ctrl+h to unhide hidden file) and copy it to gitlab => profile => setting => ssh => create new key there by pasting copied key and NOTE: public key always starts with ssh. Enjoy! Help:gitlab-Help

T-SQL string replace in Update

The syntax for REPLACE:

REPLACE (string_expression,string_pattern,string_replacement)

So that the SQL you need should be:

UPDATE [DataTable] SET [ColumnValue] = REPLACE([ColumnValue], 'domain2', 'domain1')

JavaScript validation for empty input field

       <form name="myform" action="saveNew" method="post" enctype="multipart/form-data">_x000D_
           <input type="text"   id="name"   name="name" /> _x000D_
           <input type="submit"/>_x000D_
<script language="JavaScript" type="text/javascript">_x000D_
  var frmvalidator = new Validator("myform");_x000D_
  frmvalidator.addValidation("name", "req", "Plese Enter Name");_x000D_

before using above code you have to add the gen_validatorv31.js file

IPC performance: Named Pipe vs Socket

Keep in mind that sockets does not necessarily mean IP (and TCP or UDP). You can also use UNIX sockets (PF_UNIX), which offer a noticeable performance improvement over connecting to

What is the difference between Collection and List in Java?

Java API is the best to answer this


The root interface in the collection hierarchy. A collection represents a group of objects, known as its elements. Some collections allow duplicate elements and others do not. Some are ordered and others unordered. The JDK does not provide any direct implementations of this interface: it provides implementations of more specific subinterfaces like Set and List. This interface is typically used to pass collections around and manipulate them where maximum generality is desired.

List (extends Collection)

An ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted. The user can access elements by their integer index (position in the list), and search for elements in the list.

Unlike sets, lists typically allow duplicate elements. More formally, lists typically allow pairs of elements e1 and e2 such that e1.equals(e2), and they typically allow multiple null elements if they allow null elements at all. It is not inconceivable that someone might wish to implement a list that prohibits duplicates, by throwing runtime exceptions when the user attempts to insert them, but we expect this usage to be rare.

How to dynamically create generic C# object using reflection?

I know this question is resolved but, for the benefit of anyone else reading it; if you have all of the types involved as strings, you could do this as a one liner:

IYourInterface o = (Activator.CreateInstance(Type.GetType("Namespace.TaskA`1[OtherNamespace.TypeParam]") as IYourInterface);

Whenever I've done this kind of thing, I've had an interface which I wanted subsequent code to utilise, so I've casted the created instance to an interface.

How to hide console window in python?

On Unix Systems (including GNU/Linux, macOS, and BSD)

Use nohup mypythonprog &, and you can close the terminal window without disrupting the process. You can also run exit if you are running in the cloud and don't want to leave a hanging shell process.

On Windows Systems

Save the program with a .pyw extension and now it will open with pythonw.exe. No shell window.

For example, if you have, you need to rename it to foo.pyw.

Trigger 404 in Spring-MVC controller?

This is a bit late, but if you are using Spring Data REST then there is already It also uses @ResponseStatus annotation. There is no need to create a custom runtime exception anymore.

How do I resize an image using PIL and maintain its aspect ratio?

Open your image file

from PIL import Image
im ="image.png")

Use PIL Image.resize(size, resample=0) method, where you substitute (width, height) of your image for the size 2-tuple.

This will display your image at original size:

display(im.resize((int(im.size[0]),int(im.size[1])), 0) )

This will display your image at 1/2 the size:

display(im.resize((int(im.size[0]/2),int(im.size[1]/2)), 0) )

This will display your image at 1/3 the size:

display(im.resize((int(im.size[0]/3),int(im.size[1]/3)), 0) )

This will display your image at 1/4 the size:

display(im.resize((int(im.size[0]/4),int(im.size[1]/4)), 0) )

etc etc

Spring Boot without the web server

You can use the spring-boot-starter dependency. This will not have the web stuff.


How to pass an object from one activity to another on Android

There are a couple of ways by which you can access variables or objects in other classes or Activity.

A. Database

B. Shared preferences.

C. Object serialization.

D. A class which can hold common data can be named as Common Utilities. It depends on you.

E. Passing data through Intents and Parcelable Interface.

It depends upon your project needs.

A. Database

SQLite is an open source database which is embedded into Android. SQLite supports standard relational database features like SQL syntax, transactions and prepared statements.


B. Shared preferences

Suppose you want to store username. So there will now be two things, a key username, value value.

How to store

 // Create object of SharedPreferences.
 SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);

 //Now get Editor
 SharedPreferences.Editor editor = sharedPref.edit();

 //Put your value
 editor.putString("userName", "stackoverlow");

 //Commits your edits

Using putString(), putBoolean(), putInt(), putFloat(), and putLong() you can save your desired dtatype.

How to fetch

SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
String userName = sharedPref.getString("userName", "Not Available");

C. Object serialization

Object serlization is used if we want to save an object state to send it over a network or you can use it for your purpose also.

Use Java beans and store in it as one of his fields and use getters and setter for that.

JavaBeans are Java classes that have properties. Think of properties as private instance variables. Since they're private, the only way they can be accessed from outside of their class is through methods in the class. The methods that change a property's value are called setter methods, and the methods that retrieve a property's value are called getter methods.

public class VariableStorage implements Serializable  {

    private String inString;

    public String getInString() {
        return inString;

    public void setInString(String inString) {
        this.inString = inString;

Set the variable in your mail method by using

VariableStorage variableStorage = new VariableStorage();

Then use object serialzation to serialize this object and in your other class deserialize this object.

In serialization an object can be represented as a sequence of bytes that includes the object's data as well as information about the object's type and the types of data stored in the object.

After a serialized object has been written into a file, it can be read from the file and deserialized. That is, the type information and bytes that represent the object and its data can be used to recreate the object in memory.

If you want tutorial for this refer to:

D. CommonUtilities

You can make a class by yourself which can contain common data which you frequently need in your project.


public class CommonUtilities {

    public static String className = "CommonUtilities";


E. Passing data through intents

Please refer the tutorial Android – Parcel data to pass between Activities using Parcelable classes for this option of passing data.

Why doesn't Python have a sign function?

Yes a correct sign() function should be at least in the math module - as it is in numpy. Because one frequently needs it for math oriented code.

But math.copysign() is also useful independently.

cmp() and obj.__cmp__() ... have generally high importance independently. Not just for math oriented code. Consider comparing/sorting tuples, date objects, ...

The dev arguments at regarding the omission of math.sign() are odd, because:

  • There is no separate -NaN
  • sign(nan) == nan without worry (like exp(nan) )
  • sign(-0.0) == sign(0.0) == 0 without worry
  • sign(-inf) == -1 without worry

-- as it is in numpy

Nested ng-repeat

If you have a big nested JSON object and using it across several screens, you might face performance issues in page loading. I always go for small individual JSON objects and query the related objects as lazy load only where they are required.

you can achieve it using ng-init

<td class="lectureClass" ng-repeat="s in sessions" ng-init='presenters=getPresenters('>
      <div class="presenterClass" ng-repeat="p in presenters">

The code on the controller side should look like below

$scope.getPresenters = function(id) {
    return SessionPresenters.get({id: id});

While the API factory is as follows:

angular.module('tryme3App').factory('SessionPresenters', function ($resource, DateUtils) {

        return $resource('api/session.Presenters/:id', {}, {
            'query': { method: 'GET', isArray: true},
            'get': {
                method: 'GET', isArray: true
            'update': { method:'PUT' }

how to change text in Android TextView

per your advice, i am using handle and runnables to switch/change the content of the TextView using a "timer". for some reason, when running, the app always skips the second step ("Step Two: fry egg"), and only show the last (third) step ("Step three: serve egg").

TextView t; 
private String sText;

private Handler mHandler = new Handler();

private Runnable mWaitRunnable = new Runnable() {
    public void run() {

public void onCreate(Bundle savedInstanceState) {


    mMonster = BitmapFactory.decodeResource(getResources(),

    t=new TextView(this); 

    sText = "Step One: unpack egg";

    sText = "Step Two: fry egg";        
    mHandler.postDelayed(mWaitRunnable, 3000);

    sText = "Step three: serve egg";
    mHandler.postDelayed(mWaitRunnable, 4000);      

How can I remove a key and its value from an associative array?

You may need two or more loops depending on your array:

$arr[$key1][$key2][$key3]=$value1; // ....etc

foreach ($arr as $key1 => $values) {
  foreach ($key1 as $key2 => $value) {

pandas: How do I split text in a column into multiple rows?

This seems a far easier method than those suggested elsewhere in this thread.

split rows in pandas dataframe

Make one div visible and another invisible

I don't think that you really want an iframe, do you?

Unless you're doing something weird, you should be getting your results back as JSON or (in the worst case) XML, right?

For your white box / extra space issue, try

style="display: none;"

instead of

style="visibility: hidden;"

VSCode: How to Split Editor Vertically

To change the editor in Landscape and Vertical mode, follow the steps below.

  1. For example, open two files that you have in your left or right side bar, depending on where you are placed. By default it is always on the left.

  2. Now that you have both windows open, you have to use the key combination for PC (Alt + Shift + 1) for (Windows and Linux Operating Systems) or for MAC (Cmd + Option + 1), as commented here v-andrew.

Why cannot cast Integer to String in java?

Why this is not possible:

Because String and Integer are not in the same Object hierarchy.

     /      \
    /        \
String     Integer

The casting which you are trying, works only if they are in the same hierarchy, e.g.


In this case, (A) objB or (Object) objB or (Object) objA will work.

Hence as others have mentioned already, to convert an integer to string use:

String.valueOf(integer), or Integer.toString(integer) for primitive,


Integer.toString() for the object.

How can I erase all inline styles with javascript and leave only the styles specified in the css style sheet?

If you need to just empty the style of an element then: = null;
This should do good. Hope it helps!

Correct way to select from two tables in SQL Server with no common field to join on

Cross join will help to join multiple tables with no common fields.But be careful while joining as this join will give cartesian resultset of two tables. QUERY:

 , table2,columnA
FROM table1 

Alternative way to join on some condition that is always true like

 , table2,columnA
FROM table1 
INNER JOIN table2 ON 1=1

But this type of query should be avoided for performance as well as coding standards.

Python - List of unique dictionaries

Here's a reasonably compact solution, though I suspect not particularly efficient (to put it mildly):

>>> ds = [{'id':1,'name':'john', 'age':34},
...       {'id':1,'name':'john', 'age':34},
...       {'id':2,'name':'hanna', 'age':30}
...       ]
>>> map(dict, set(tuple(sorted(d.items())) for d in ds))
[{'age': 30, 'id': 2, 'name': 'hanna'}, {'age': 34, 'id': 1, 'name': 'john'}]

How can I find which tables reference a given table in Oracle SQL Developer?

To add to the above answer for sql developer plugin, using the below xml will help in getting the column associated with the foreign key.

        <item type="editor" node="TableNode" vertical="true">
        <title><![CDATA[FK References]]></title>
                <![CDATA[select a.owner,
                         from   all_constraints a
                         join   all_cons_columns b ON b.constraint_name = a.constraint_name
                         where  a.constraint_type = 'R'
                                and exists(
                                   select 1
                                   from   all_constraints
                                   where  constraint_name=a.r_constraint_name
                                          and constraint_type in ('P', 'U')
                                          and table_name = :OBJECT_NAME
                                          and owner = :OBJECT_OWNER)
                                   order by table_name, constraint_name]]>

What does "connection reset by peer" mean?

This means that a TCP RST was received and the connection is now closed. This occurs when a packet is sent from your end of the connection but the other end does not recognize the connection; it will send back a packet with the RST bit set in order to forcibly close the connection.

This can happen if the other side crashes and then comes back up or if it calls close() on the socket while there is data from you in transit, and is an indication to you that some of the data that you previously sent may not have been received.

It is up to you whether that is an error; if the information you were sending was only for the benefit of the remote client then it may not matter that any final data may have been lost. However you should close the socket and free up any other resources associated with the connection.

Handle spring security authentication exceptions with @ExceptionHandler

Ok, I tried as suggested writing the json myself from the AuthenticationEntryPoint and it works.

Just for testing I changed the AutenticationEntryPoint by removing response.sendError

public class RestAuthenticationEntryPoint implements AuthenticationEntryPoint{

    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authenticationException) throws IOException, ServletException {
        response.getOutputStream().println("{ \"error\": \"" + authenticationException.getMessage() + "\" }");


In this way you can send custom json data along with the 401 unauthorized even if you are using Spring Security AuthenticationEntryPoint.

Obviously you would not build the json as I did for testing purposes but you would serialize some class instance.

In Spring Boot, you should add it to http.authenticationEntryPoint() part of SecurityConfiguration file.

Installing a specific version of angular with angular cli

Specify the version you want in the 'dependencies' section of your package.json, then from your root project folder in the console/terminal run this:

npm install

For example, the following will specifically install v4.3.4

"dependencies": {
    "@angular/common": "4.3.4",
    "@angular/compiler": "4.3.4",
    "@angular/core": "4.3.4",
    "@angular/forms": "4.3.4",
    "@angular/http": "4.3.4",
    "@angular/platform-browser": "4.3.4",
    "@angular/platform-browser-dynamic": "4.3.4",
    "@angular/router": "4.3.4",

You can also add the following modifiers to the version number to vary how specific you need the version to be:

caret ^

Updates you to the most recent major version, as specified by the first number:


will load the latest 4.x.x release, but will not load 5.x.x

tilde ~

Update you to the most recent minor version, as specified by the second number:


will load the latest 4.3.x release, but will not load 4.4.x

Find if a textbox is disabled or not using jquery

You can check if a element is disabled or not with this:

if($("#slcCausaRechazo").prop('disabled') == false)
//your code to realice 

Angular 2: import external js file into component

Let's say you have added a file "xyz.js" under assets/js folder in some Angular project in Visual-Studio, then the easiest way to include that file is to add it to .angular-cli.json

"scripts": [ "assets/js/xyz.js" ],

You should be able to use this JS file's functionality in your component or .ts files.

Why do we use volatile keyword?

Consider this code,

int some_int = 100;

while(some_int == 100)
   //your code

When this program gets compiled, the compiler may optimize this code, if it finds that the program never ever makes any attempt to change the value of some_int, so it may be tempted to optimize the while loop by changing it from while(some_int == 100) to something which is equivalent to while(true) so that the execution could be fast (since the condition in while loop appears to be true always). (if the compiler doesn't optimize it, then it has to fetch the value of some_int and compare it with 100, in each iteration which obviously is a little bit slow.)

However, sometimes, optimization (of some parts of your program) may be undesirable, because it may be that someone else is changing the value of some_int from outside the program which compiler is not aware of, since it can't see it; but it's how you've designed it. In that case, compiler's optimization would not produce the desired result!

So, to ensure the desired result, you need to somehow stop the compiler from optimizing the while loop. That is where the volatile keyword plays its role. All you need to do is this,

volatile int some_int = 100; //note the 'volatile' qualifier now!

In other words, I would explain this as follows:

volatile tells the compiler that,

"Hey compiler, I'm volatile and, you know, I can be changed by some XYZ that you're not even aware of. That XYZ could be anything. Maybe some alien outside this planet called program. Maybe some lightning, some form of interrupt, volcanoes, etc can mutate me. Maybe. You never know who is going to change me! So O you ignorant, stop playing an all-knowing god, and don't dare touch the code where I'm present. Okay?"

Well, that is how volatile prevents the compiler from optimizing code. Now search the web to see some sample examples.

Quoting from the C++ Standard ($

[..] volatile is a hint to the implementation to avoid aggressive optimization involving the object because the value of the object might be changed by means undetectable by an implementation.[...]

Related topic:

Does making a struct volatile make all its members volatile?

How can I check whether an array is null / empty?

I am from .net background. However, java/c# are more/less same.

If you instantiate a non-primitive type (array in your case), it won't be null.
e.g. int[] numbers = new int[3];
In this case, the space is allocated & each of the element has a default value of 0.

It will be null, when you don't new it up.

int[] numbers = null; // changed as per @Joachim's suggestion.
if (numbers == null)
   System.out.println("yes, it is null. Please new it up");

Open File in Another Directory (Python)

import os
import os.path
import shutil

You find your current directory:

d = os.getcwd() #Gets the current working directory

Then you change one directory up:

os.chdir("..") #Go up one directory from working directory

Then you can get a tupple/list of all the directories, for one directory up:

o = [os.path.join(d,o) for o in os.listdir(d) if os.path.isdir(os.path.join(d,o))] # Gets all directories in the folder as a tuple

Then you can search the tuple for the directory you want and open the file in that directory:

for item in o:
    if os.path.exists(item + '\\testfile.txt'):
    file = item + '\\testfile.txt'

Then you can do stuf with the full file path 'file'

Loop over html table and get checked checkboxes (JQuery)

The following code snippet enables/disables a button depending on whether at least one checkbox on the page has been checked.
$('input[type=checkbox]').change(function () {
    $('#test > tbody  tr').each(function () {
        if ($('input[type=checkbox]').is(':checked')) {
        } else {
            $('#btnexcellSelect').attr('disabled', 'disabled');
        if ($(this).is(':checked')){
            console.log( $(this).attr('id'));

Here is demo in JSFiddle.

SQLAlchemy create_all() does not create tables

You should put your model class before create_all() call, like this:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)

app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql+psycopg2://login:pass@localhost/flask_app'
db = SQLAlchemy(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True)
    email = db.Column(db.String(120), unique=True)

    def __init__(self, username, email):
        self.username = username = email

    def __repr__(self):
        return '<User %r>' % self.username


admin = User('admin', '[email protected]')
guest = User('guest', '[email protected]')
users = User.query.all()
print users

If your models are declared in a separate module, import them before calling create_all().

Say, the User model is in a file called,

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)

app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql+psycopg2://login:pass@localhost/flask_app'
db = SQLAlchemy(app)

# See important note below
from models import User


admin = User('admin', '[email protected]')
guest = User('guest', '[email protected]')
users = User.query.all()
print users

Important note: It is important that you import your models after initializing the db object since, in your _you also need to import the db object from this module.

Multiple conditions with CASE statements

Another way based on amadan:

    SELECT * FROM [Purchasing].[Vendor] WHERE  

      ( (@url IS null OR @url = '' OR @url = 'ALL') and   PurchasingWebServiceURL LIKE '%')

       ( @url = 'blank' and  PurchasingWebServiceURL = '')
        (@url = 'fail' and  PurchasingWebServiceURL NOT LIKE '%treyresearch%')
    or( (@url not in ('fail','blank','','ALL') and @url is not null and 
          PurchasingWebServiceUrl Like '%'+@ur+'%') 

Correct way to quit a Qt program?

While searching this very question I discovered this example in the documentation.

QPushButton *quitButton = new QPushButton("Quit");
connect(quitButton, &QPushButton::clicked, &app, &QCoreApplication::quit, Qt::QueuedConnection);

Mutatis mutandis for your particular action of course.

Along with this note.

It's good practice to always connect signals to this slot using a QueuedConnection. If a signal connected (non-queued) to this slot is emitted before control enters the main event loop (such as before "int main" calls exec()), the slot has no effect and the application never exits. Using a queued connection ensures that the slot will not be invoked until after control enters the main event loop.

It's common to connect the QGuiApplication::lastWindowClosed() signal to quit()

IE8 support for CSS Media Query

IE8 (and lower versions) and Firefox prior to 3.5 do not support media query. Safari 3.2 partially supports it.

There are some workarounds that use JavaScript to add media query support to these browsers. Try these:

Media Queries jQuery plugin (only deals with max/min width)

css3-mediaqueries-js – a library that aims to add media query support to non-supporting browsers

How can I get two form fields side-by-side, with each field’s label above the field, in CSS?

This worked perfectly for me without css. I think css would put some icing on the cake though.

        <label for="First Name" >First Name:</label>
            <input type="text" name="username" size="15" maxlength="30" />
        <label for="Last Name" >Last Name:</label>
            <input type="text" name="username" size="15" maxlength="30" />

addEventListener not working in IE8


if (_checkbox.addEventListener) {
    _checkbox.addEventListener("click", setCheckedValues, false);
else {
    _checkbox.attachEvent("onclick", setCheckedValues);

Update:: For Internet Explorer versions prior to IE9, attachEvent method should be used to register the specified listener to the EventTarget it is called on, for others addEventListener should be used.

How do I return multiple values from a function in C?

Create a struct and set two values inside and return the struct variable.

struct result {
    int a;
    char *string;

You have to allocate space for the char * in your program.

How to temporarily disable a click handler in jQuery?

I just barely ran into this problem when trying to display a loading spinner while I waited for a function to complete. Because I was appending the spinner into the HTML, the spinner would be duplicated each time the button was clicked, if you're not against defining a variable on the global scale, then this worked well for me.

    var hasCardButtonBeenClicked = '';
    $(".js-mela-card-button").on("click", function(){  
            hasCardButtonBeenClicked = true;
            $(this).append('<i class="fa fa-circle-o-notch fa-spin" style="margin-left: 3px; font-size: 15px;" aria-hidden="true"></i>');

Notice, all I'm doing is declaring a variable, and as long as its value is null, the actions following the click will occur and then subsequently set the variables value to "true" (it could be any value, as long as it's not empty), further disabling the button until the browser is refreshed or the variable is set to null.

Looking back it probably would have made more sense to just set the hasCardButtonBeenClicked variable to "false" to begin with, and then alternate between "true" and "false" as needed.

Splitting a string into chunks of a certain size

In a combination of dove+Konstatin's answers...

static IEnumerable<string> WholeChunks(string str, int chunkSize) {
    for (int i = 0; i < str.Length; i += chunkSize) 
        yield return str.Substring(i, chunkSize);

This will work for all strings that can be split into a whole number of chunks, and will throw an exception otherwise.

If you want to support strings of any length you could use the following code:

static IEnumerable<string> ChunksUpto(string str, int maxChunkSize) {
    for (int i = 0; i < str.Length; i += maxChunkSize) 
        yield return str.Substring(i, Math.Min(maxChunkSize, str.Length-i));

However, the the OP explicitly stated he does not need this; it's somewhat longer and harder to read, slightly slower. In the spirit of KISS and YAGNI, I'd go with the first option: it's probably the most efficient implementation possible, and it's very short, readable, and, importantly, throws an exception for nonconforming input.

How do I pass a method as a parameter in Python

Yes it is possible. Just call it:

class Foo(object):
    def method1(self):
    def method2(self, method):
        return method()

foo = Foo()