package 单例模式;/** * 单例设计模式之安全的懒汉式 */class Single{	private static Single single= null;	//私有构造方法	private Single() {	}	//对外提供公有的获取内部创建的Single对象	public static Single getInstance(){		if(single==null)		{			synchronized(Single.class)			{				if(single==null)				{					single = new Single();				}			}		}		return single;	}}public class Test {	public static void main(String[] args) {		Single s1 = Single.getInstance();		Single s2 = Single.getInstance();		System.out.println(s1);		System.out.println(s2);		System.out.println("==比較s1和s2两个对象:"+(s1==s2));		System.out.println("equals比較s1和s2两个对象:"+(s1.equals(s2)));	}}