1.可见性的代码验证说明

1.在修改完number值以后，while循环并没有检查到

package com.mydemo;

import java.util.concurrent.TimeUnit;

public class MyData {
    public  int number=0;
    public void add_to_60(){

        this.number=60;
    }


}

class VolatileDemo{
    public static void main(String[] args) {

        MyData myData = new MyData();
        new Thread(()->{
            System.out.println(Thread.currentThread().getName() + "\t come in");
            try {
                            TimeUnit.SECONDS.sleep(3);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }

            myData.add_to_60();
            System.out.println(Thread.currentThread().getName() + "\t update number value:" + myData.number);
        },"AAA").start();

        while (myData.number==0){}
        System.out.println(Thread.currentThread().getName() + "\t mission is over"+ myData.number);

    }



}

执行结果：

 

 

 2.用volatile修饰number后

package com.mydemo;

import java.util.concurrent.TimeUnit;

public class MyData {
    public  volatile int number=0;
    public void add_to_60(){

        this.number=60;
    }


}

class VolatileDemo{
    public static void main(String[] args) {

        MyData myData = new MyData();
        new Thread(()->{
            System.out.println(Thread.currentThread().getName() + "\t come in");
            try {
                            TimeUnit.SECONDS.sleep(3);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }

            myData.add_to_60();
            System.out.println(Thread.currentThread().getName() + "\t update number value:" + myData.number);
        },"AAA").start();

        while (myData.number==0){}
        System.out.println(Thread.currentThread().getName() + "\t mission is over"+ myData.number);

    }



}

执行结果：

 

 数值被修改后被while判断到