The new interface of much waited Internet Explorer 9 has been revealed following an article which was published by one of Microsoft’s Russian subsidiaries. Though it was removed quickly, but it was too late. [...]

Today we are going to see one of the design patterns abstract factory. Its one level of abstraction higher than factory pattern.The main use of Abstract Factory Patten is that is isolates the concrete classes which are generated. [...]

Singletons are the design pattern when you want only one instance of a class created. You make the constructor private, and give access to the instantiated object via a static instance method that creates the object if it has not been created already.
The singleton class is threadsafe lazy instantiation. I hope many would be knowing on lazy instantiation. With lazy instantiation, a program refrains from creating certain resources until the resource is first needed — freeing valuable memory space. In lame man words, loading the resource only when its needed.
[codesyntax lang="java5"]
public class YourSingletonClass{
private static YourSingletonClassinstance = new YourSingletonClass();
public static YourSingletonClass getInstance(){
return instance;
}
private YourSingletonClass(){
}
}
[/codesyntax]
How do we ensure only one the same instance is returned?

We write a public static getter or access method to get the instance of the Singleton Object at runtime. First time the object is created inside this method as it is null. Subsequent calls to this method returns the same object created as the object is globally declared (private) and the hence the same referenced object is returned.

Today i was going through an requirement on how to create components in runtime where we have parse an XML as input and then create components in the stage. [...]

An associative array is the conventional workaround of the coding world.. In an associative array, we can associate any key or index we want with each value. [...]

The Singleton pattern is very similar to creator pattern. This is very widely used pattern. Now a question might raise in the mind that why do we need this pattern and when it should be applied. Let us take a situation where you want to build a chess game. Where does the Singleton Pattern apply here? [...]