多线程单例

/**
*
*/
package thread.meeting;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

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

private static volatile Singleton singleton = null;private Singleton(){}public static Singleton getSingleton(){    synchronized (Singleton.class) {        if(Singleton.singleton==null){            Singleton.singleton = new Singleton();        }    }    return Singleton.singleton;}public static void main(String[] args) {    ExecutorService newFixedThreadPool = Executors.newFixedThreadPool(50);    for (int i = 0; i < 50; i++) {        newFixedThreadPool.execute(new SingletonRunner());    }    newFixedThreadPool.shutdown();}

}