hai friend
singleton class means,We have to create one object for one class.
By using private constuctor(i.e, we have to diclare your default constuctor as private).With this we can get singleton java class.That mean that java class will allow one object to access that class.
With this we can avoid multithreading.This Singleton java class will use in Bank applications and in credit card transaction logic etc. to avoid multiple transaction at a time(to avoid multithreading).

Thanks you friend

Hi,


Code for Singleton Design Pattern

public class SingletonPattern{
private static SingletonPattern instance;
private SingletonPattern(){}
public static synchronized SingletonPattern getInstance(){
if (instance == null)
{
instance = new SingletonPattern();
}
return instance;
}
public static void main(String arg[]){
System.out.println("The output of two instance:");
SingletonPattern sp=new SingletonPattern();
System.out.println("First Instance: "+sp.getInstance());
sp=new SingletonPattern();
System.out.println("Second Instance:"+sp.getInstance());
}
}

Thanks