读volatile文章的自我理解

//一下代码主要阐述volatiile的作用
package com.example.demo;

public class Test {

    public static void main(String[] args) {
       Aboing a = new Aboing();
       a.start();
//       synchronized (a){
           while (true){
               if(a.isFlag()){
                   System.out.println("nice");
               }

           }
//       }

    }

}

class Aboing extends Thread{
    private volatile boolean flag = false;//volatile 保证主内存为最新变量值

    public boolean isFlag(){
        return flag;
    }

    @Override
    public void run() {
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        flag = true;
        System.out.println("flag  =  "+ flag);
    }
}