Tutorial by Examples: ad

Inititialization by one thread

In most cases all data that is accessed by several threads should be initialized before the threads are created. This ensures that all threads start with a clear state and no race condition occurs. If this is not possible once_flag and call_once can be used #include <threads.h> #include &lt...

C Language • Threads (native)

Using XmlAdapter to trim string.

package com.example.xml.adapters; import javax.xml.bind.annotation.adapters.XmlAdapter; public class StringTrimAdapter extends XmlAdapter<String, String> { @Override public String unmarshal(String v) throws Exception { if (v == null) return null; ...

Java Language • JAXB

Adding a semicolon to a #define

It is easy to get confused in the C preprocessor, and treat it as part of C itself, but that is a mistake because the preprocessor is just a text substitution mechanism. For example, if you write /* WRONG */ #define MAX 100; int arr[MAX]; the code expands to int arr[100;]; which is a synta...

C Language • Common pitfalls

Use gradle.properties for central versionnumber/buildconfigurations

You can define central config info's in a separate gradle include file Centralizing dependencies via "dependencies.gradle" file a stand alone properties file Versioning your builds via "version.properties" file or do it with root gradle.properties file the project structu...

Android • Gradle for Android

How to add Dagger 2 in build.gradle

Since the release of Gradle 2.2, the use of the android-apt plugin is no longer used. The following method of setting up Dagger 2 should be used. For older version of Gradle, use the previous method shown below. For Gradle >= 2.2 dependencies { // apt command comes from the android-apt plu...

Android • Dagger 2

Adding File Compression to your project

In Solution Explorer go to your project, right click on References then Add reference… Search for Compression and select System.IO.Compression.FileSystem then press OK. Add Imports System.IO.Compression to the top of your code file (before any class or module, with the other Imports statements)....

Visual Basic .NET Language • File/Folder Compression

ADO.NET Connections

ADO.NET Connections are one of the simplest ways to connect to a database from a C# application. They rely on the use of a provider and a connection string that points to your database to perform queries against. Common Data Provider Classes Many of the following are classes that are commonly used...

C# Language • Accessing Databases

Check if the product was correctly loaded

$productFound = ($product->getId() !== null)

magento • Get Products from Database

Deleting a derived object via a pointer to a base class that doesn't have a virtual destructor.

class base { }; class derived: public base { }; int main() { base* p = new derived(); delete p; // The is undefined behavior! } In section [expr.delete] §5.3.5/3 the standard says that if delete is called on an object whose static type does not have a virtual destructor: if the...

C++ • Undefined Behavior

Animate at a specified interval (add a new rectangle every 1 second)

This example adds a new rectangle to the canvas every 1 second (== a 1 second interval) Annotated Code: <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid red; } </style> <script> window.onload=(functio...

html5-canvas • Animation

Download

A distribution can be downloaded from the Apache Struts website. The full distribution contains: the struts2-core.jar file related dependencies example applications a copy of the documentation in HTML format the complete source code. Blank Application The blank web application in the dis...

struts2 • Getting started with struts2

Heading scope

th elements are very commonly used to indicate headings for table rows and columns, like so: <table> <thead> <tr> <td></td> <th>Column Heading 1</th> <th>Column Heading 2</th> </tr...

HTML • Tables

Accessing a dangling reference

It is illegal to access a reference to an object that has gone out of scope or been otherwise destroyed. Such a reference is said to be dangling since it no longer refers to a valid object. #include <iostream> int& getX() { int x = 42; return x; } int main() { int& r...

C++ • Undefined Behavior

Connecting overloaded signals/slots

While being better in many regards, the new connection syntax in Qt5 has one big weakness: Connecting overloaded signals and slots. In order to let the compiler resolve the overloads we need to use static_casts to member function pointers, or (starting in Qt 5.7) qOverload and friends: #include &lt...

Qt • Signals and Slots

Installation of Hadoop on ubuntu

Creating Hadoop User: sudo addgroup hadoop Adding a user: sudo adduser --ingroup hadoop hduser001 Configuring SSH: su -hduser001 ssh-keygen -t rsa -P "" cat .ssh/id rsa.pub >> .ssh/authorized_keys Note: If you get errors [bash: .ssh/authorized_keys: No such file or di...

hadoop • Getting started with hadoop

Tint a drawable

A drawable can be tinted a certain color. This is useful for supporting different themes within your application, and reducing the number of drawable resource files. Using framework APIs on SDK 21+: Drawable d = context.getDrawable(R.drawable.ic_launcher); d.setTint(Color.WHITE); Using android...

Android • Drawables

Constructing an IPv4 header

Sometimes you have to deal with structures defined in terms of C data types from Perl. One such application is the creation of raw network packets, in case you want to do something fancier than what the regular socket API has to offer. This is just what pack() (and unpack() of course) is there for. ...

Perl Language • Pack and unpack

Negating address range

$ cat ip.txt address range substitution 1234 search pattern sample Add Sub Mul Div Deleting lines other than address specified $ sed '/[0-9]/!d' ip.txt 1234 $ sed -n '/[0-9]/p' ip.txt 1234 $ sed '$!d' ip.txt Add Sub Mul Div $ sed -n '$p' ip.txt Add Sub Mul Div ...

sed • Address and address range

Traditional style to Lambda style

Traditional way interface MathOperation{ boolean unaryOperation(int num); } public class LambdaTry { public static void main(String[] args) { MathOperation isEven = new MathOperation() { @Override public boolean unaryOperation(int num) { ...

Java Language • Lambda Expressions

How to kill a thread

You call use Thread.kill or Thread.terminate: thr = Thread.new { ... } Thread.kill(thr)

Ruby Language • Thread