Tutorial by Examples: e

onUpgrade() method

SQLiteOpenHelper is a helper class to manage database creation and version management. In this class, the onUpgrade() method is responsible for upgrading the database when you make changes to the schema. It is called when the database file already exists, but its version is lower than the one spec...

Android • SQLite

Forcing a static constructor to be called

While static constructors are always called before the first usage of a type it's sometimes useful to be able to force them to be called and the RuntimeHelpers class provide an helper for it: using System.Runtime.CompilerServices; // ... RuntimeHelpers.RunClassConstructor(typeof(Foo).TypeHand...

C# Language • Constructors and Finalizers

Installation or Setup

To prepare your web site or web application to use Kendo UI, simply add the style and script files in the <head> section of your page. CDN services are provided for the minified versions of official Kendo UI releases, for both HTTP and HTTPS protocols. JQuery is also required to use Kendo UI...

kendo-ui • Getting started with kendo-ui

Singleton Class

What is a Singleton Class? A singleton class returns the same instance no matter how many times an application requests it. Unlike a regular class, A singleton object provides a global point of access to the resources of its class. When to Use Singleton Classes? Singletons are used in situations ...

Objective-C Language • Classes and Objects

Create a box-and-whisker plot with boxplot() {graphics}

This example use the default boxplot() function and the irisdata frame. > head(iris) Sepal.Length Sepal.Width Petal.Length Petal.Width Species 1 5.1 3.5 1.4 0.2 setosa 2 4.9 3.0 1.4 0.2 setosa 3 4.7 3.2 ...

R Language • boxplot

Creating a new program using Mono

First install Mono by going through the install instructions for the platform of your choice as described in their installation section. Mono is available for Mac OS X, Windows and Linux. After installation is done, create a text file, name it HelloWorld.cs and copy the following content into it: ...

C# Language • Getting started with C# Language

Using pointer parameters to return multiple values

A common pattern in C, to easily imitate returning multiple values from a function, is to use pointers. #include <stdio.h> void Get( int* c , double* d ) { *c = 72; *d = 175.0; } int main(void) { int a = 0; double b = 0.0; Get( &a , &b ); pr...

C Language • Function Parameters

"Hello, world!" in the REPL

The Clojure community puts a large emphasis on interactive development, so quite a lot of interaction with Clojure happens within a REPL (read-eval-print-loop). When you input an expression into it, Clojure reads it, evaluates it, and prints the result of the evaluation, all in a loop. You should b...

clojure • Getting started with clojure

Multiple Inheritance

Multiple inheritance is a feature that allows one class to inherit from multiple classes(i.e., more than one parent). Ruby does not support multiple inheritance. It only supports single-inheritance (i.e. class can have only one parent), but you can use composition to build more complex classes using...

Ruby Language • Inheritance

Installation or Setup

Executable File Download the .exe from http://dev.sitecore.net/ and double-click to start. This .exe will do everything for you - attach databases, modify host file, and set folder permissions. The only downside is that it leaves an entry in the registry under [HKEY_LOCAL_MACHINE\SOFTWARE\Sitecore...

sitecore • Getting started with sitecore

Hello World

For installation instructions on elixir check here, it describes instructions related to different platforms. Elixir is a programming language that is created using erlang, and uses erlang's BEAM runtime (like JVM for java). We can use elixir in two modes: interactive shell iex or directly running...

Elixir Language • Getting started with Elixir Language

Inner Join

Inner join returns only those records/rows that match/exists in both the tables based on one or more conditions (specified using ON keyword). It is the most common type of join. The general syntax for inner join is: SELECT * FROM table_1 INNER JOIN table_2 ON table_1.column_name = table_2.col...

Microsoft SQL Server • Join

Outer Join

Left Outer Join LEFT JOIN returns all rows from the left table, matched to rows from the right table where the ON clause conditions are met. Rows in which the ON clause is not met have NULL in all of the right table's columns. The syntax of a LEFT JOIN is: SELECT * FROM table_1 AS t1 LEFT JOIN ta...

Microsoft SQL Server • Join

Manually triggering GC

You can manually trigger the Garbage Collector by calling System.gc(); However, Java does not guarantee that the Garbage Collector has run when the call returns. This method simply "suggests" to the JVM (Java Virtual Machine) that you want it to run the garbage collector, but does not ...

Java Language • Java Memory Management

Enums with Abstract Methods

Enums can define abstract methods, which each enum member is required to implement. enum Action { DODGE { public boolean execute(Player player) { return player.isAttacking(); } }, ATTACK { public boolean execute(Player player) { re...

Java Language • Enums

Default Values for Properties

Setting a default value can be done by using Initializers (C#6) public class Name { public string First { get; set; } = "James"; public string Last { get; set; } = "Smith"; } If it is read only you can return values like this: public class Name { pu...

C# Language • Properties

Parallel.ForEach

An example that uses Parallel.ForEach loop to ping a given array of website urls. static void Main() { string [] urls = { "www.stackoverflow.com", "www.google.net", "www.facebook.com", "www.twitter.com" ...

C# Language • Task Parallel Library

Parallel.For

An example that uses Parallel.For loop to ping a given array of website urls. static void Main() { string [] urls = { "www.stackoverflow.com", "www.google.net", "www.facebook.com", "www.twitter.com" }; ...

C# Language • Task Parallel Library

Parallel.Invoke

Invoking methods or actions in parallel (Parallel region) static void Main() { string [] urls = { "www.stackoverflow.com", "www.google.net", "www.facebook.com", "www.twitter.com" }; System.Thr...

C# Language • Task Parallel Library

Interactive Rebase

This example aims to describe how one can utilize git rebase in interactive mode. It is expected that one has a basic understanding of what git rebase is and what it does. Interactive rebase is initiated using following command: git rebase -i The -i option refers to interactive mode. Using inte...

Git • Rebasing