线程sleep 共享变量

package com.test.gateway.test;

import lombok.SneakyThrows;

import java.util.concurrent.TimeUnit;

public class SyncTest {

	
	public static void main(String[] args)  {
		ThreadTest threadTest = new ThreadTest();
		threadTest.start();
		for(;;) {
			if(threadTest.isFlag()) {
				System.out.println("主线程运行.....");
			}
		}
	}
	
}
class ThreadTest extends Thread {
	private     boolean flag = false;

	@SneakyThrows
	@Override
	public void run() {

		for (int i = 0; i <10; i++) {
			System.out.println(i);
		}

		flag = true;
		System.out.println("flag==="+flag);
		super.run();
	}

	public boolean isFlag() {
		return flag;
	}

	public void setFlag(boolean flag) {
		this.flag = flag;
	}
	
	
}

class ThreadTest extends Thread {
	private     boolean flag = false;

	@SneakyThrows
	@Override
	public void run() {

		for (int i = 0; i <100; i++) {
			System.out.println(i);
		}

		flag = true;
		System.out.println("flag==="+flag);
		super.run();
	}

	public boolean isFlag() {
		return flag;
	}

	public void setFlag(boolean flag) {
		this.flag = flag;
	}
	
	
}

class ThreadTest extends Thread {
	private     boolean flag = false;

	@SneakyThrows
	@Override
	public void run() {

		TimeUnit.SECONDS.sleep(3);

		flag = true;
		System.out.println("flag==="+flag);
		super.run();
	}

	public boolean isFlag() {
		return flag;
	}

	public void setFlag(boolean flag) {
		this.flag = flag;
	}
	
	
}

class ThreadTest extends Thread {
	private     boolean flag = false;

	@SneakyThrows
	@Override
	public void run() {

		TimeUnit.SECONDS.sleep(10);

		flag = true;
		System.out.println("flag==="+flag);
		super.run();
	}

	public boolean isFlag() {
		return flag;
	}

	public void setFlag(boolean flag) {
		this.flag = flag;
	}
	
	
}

当一个线程再执行过程再很短的时间内修改了共享变量，那么即使我们不用

volatile关键字去修饰这个变量，也会将更改的数据从工作内存刷新到主内存，这个时间大概再3毫秒左右，那也就是说volatile关键字表示不管怎么样我修改了要告诉别人