设计模式之饿汉单例

package design.singleton.demo;//饿汉式单例public class SingletonHungryEntity {    //直接创建对象实例    private static SingletonHungryEntity s = new SingletonHungryEntity();    // 实例输出出口    public static SingletonHungryEntity getSingletonEntity() {        return s;    }    // 私有化构造方法,让外部无法通过new创建    private SingletonHungryEntity() {    }}

package design.singleton.demo;public class Main {    public static void main(String[] args) {        // 创建多线程验证        Thread t1 = new Thread() {            @Override            public void run() {                SingletonHungryEntity s = SingletonHungryEntity.getSingletonEntity();                System.out.println("t1线程获取对象的hashcode: " + s.hashCode());            }        };        Thread t2 = new Thread() {            @Override            public void run() {                SingletonHungryEntity s = SingletonHungryEntity.getSingletonEntity();                System.out.println("t2线程获取对象的hashcode: " + s.hashCode());            }        };        Thread t3 = new Thread() {            @Override            public void run() {                SingletonHungryEntity s = SingletonHungryEntity.getSingletonEntity();                System.out.println("t3线程获取对象的hashcode: " + s.hashCode());            }        };        t1.start();        t2.start();        t3.start();    }}// t3线程获取对象的hashcode: 475341210// t1线程获取对象的hashcode: 475341210// t2线程获取对象的hashcode: 475341210