Singleton Design Pattern

• Single Instance
• Global Access
• Lazy or Eager Initialisation Support creating the instance either when needed (lazy) or when the class is loaded (eager).
• Thread Safety
• Private Constructor

/*package whatever //do not write package name here */
import java.io.*;
class Singleton {
    // static class
    private static Singleton instance;
    private Singleton()
    {
        System.out.println("Singleton is Instantiated.");
    }
    public static Singleton getInstance()
    {
        if (instance == null)
            instance = new Singleton();
        return instance;
    }
    public static void doSomething()
    {
        System.out.println("Somethong is Done.");
    }
}