doubledouble

/**
 * 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){

doubledouble

public class Test{
    public String a = "hello";
}

doubledouble

<h1>发觉自己的爱好！做有意义的事，倾听</h1>