单例模式 (一) 立即加载/"饿汉模式"

package com.multithreading.pc68;

/**
 * Created by nanzhou on 2017/6/29.
 */
public class MyObject {

    private static MyObject myObject = new MyObject();

    private MyObject (){

    }

    public static MyObject getInstance(){

        //本版本为立即加载 缺点是不能有其他变量
        //因为getInstance() 方法没有同步 可能存在非线程安全的问题
        return myObject;
    }
}

package com.multithreading.pc68;

/**
 * Created by nanzhou on 2017/6/29.
 */
public class MyThread extends Thread {

    @Override
    public void run() {

        System.out.println(MyObject.getInstance().hashCode());
    }
}
package com.multithreading.pc68;

/**
 * Created by nanzhou on 2017/6/29.
 */
public class Run {

    public static void main(String[] args) {

        MyThread myThread1 = new MyThread();
        MyThread myThread2 = new MyThread();
        MyThread myThread3 = new MyThread();

        myThread1.start();
        myThread2.start();
        myThread3.start();

    }
}