Singleton

Singleton

/**
 * see http://caterpillar.onlyfun.net/Gossip/DesignPattern/SingletonPattern.htm
 * http://www.jackforfun.com/2007/07/java-synchronized.html
 */
public class Singleton {
    private static Singleton instance = null;
    private Singleton(){}
    public static Singleton getInstance() {
        if (instance == null){
            synchronized(Singleton.class){
                if(instance == null) {
                     instance = new Singleton();
                }
            }
        }
        return instance;
    }
}