java设计模式——单例模式之饿汉式（方式一）

一、饿汉式代码：

1、创建一个饿汉式单例类

package com.rf.designPatterns.singleton.hungrySingleton;
/**
 * @description: 饿汉式单例模式
 * @author: xiaozhi
 * @create: 2020-05-23 22:26
 */
public class HungrySingleton {
    //直接声明一个需要被单例的对象,并初始化
    private final static HungrySingleton hungrySingleton=new HungrySingleton();

    //私有的构造器，不被外部所访问
    private HungrySingleton(){
        System.out.println("构造方法。。。。");
    }
    //提供一个外部获取HungrySingleton对象的静态方法
    public static HungrySingleton getInstance(){
        return hungrySingleton;
    }

}

2、创建一个多线程类

package com.rf.designPatterns.singleton.hungrySingleton;

/**
 * @description: 多线程类
 * @author: xiaozhi
 * @create: 2020-05-23 22:49
 */
public class MyThread implements Runnable{
    @Override
    public void run() {
        HungrySingleton instance = HungrySingleton.getInstance();
        System.out.println(Thread.currentThread().getName()+": "+instance);
    }
}

3、创建一个测试类

package com.rf.designPatterns.singleton.hungrySingleton;

/**
 * @description: 测试
 * @author: xiaozhi
 * @create: 2020-05-23 22:35
 */
public class Test {
    public static void main(String[] args) {
        Thread thread1 = new Thread(new MyThread());
        Thread thread2 = new Thread(new MyThread());
        thread1.start();
        thread2.start();
        System.out.println("=========");
    }
}

二、输出结果: