Eager initialization

See Singleton Pattern here...

If the program will always need an instance, or if the cost of creating the instance is not too large in terms of time/resources, the programmer can switch to eager initialization, which always creates an instance.


Singleton.java

 
package me.dhanoop.singleton;

/**
 *
 * @author dhanoopbhaskar
 */
public class Singleton {

    private static final Helper helper = new Helper();

    public static Helper getHelper() {
        return helper;
    }

    public static void main(String[] args) {

        Runnable runnable = new Runnable() {

            @Override
            public void run() {
                Singleton.getHelper();
            }
        };

        new Thread(runnable).start();
        new Thread(runnable).start();
        new Thread(runnable).start();
    }
}

Output:
Created Helper Object

Advantages:

• The instance is not constructed until the class is used.
• There is no need of synchronization, which means all the threads will see the same instance even without expensive locking mechanism.
• The final keyword means that the instance cannot be redefined, ensuring that one (and only one) instance ever exists.