I feel like there is nothing that needs to be recorded during this period of time, and I personally don’t have any ideas, but I will still have to remember and write more in the future

package cn.xf.cp.ch02.item66;

import java.util.concurrent.TimeUnit;

import org.junit.Test;

public class StopThread
{
    /**
     * 停止線程變量
     */
    private static boolean stopRequested;
    
    //吧對(duì)變量的讀和寫方法都進(jìn)行同步
    private static synchronized void requestStop()
    {
        stopRequested = true;
    }
    
    private static synchronized boolean stopRequested()
    {
        return stopRequested;
    }
    
    /**
     * 停止線程變量,這個(gè)使用關(guān)鍵字volatile使每個(gè)線程都是獲取到最新的值
     */
    private static volatile boolean stopRequested2;
    
    @Test
    public void test()
    {
        Thread backgroundThread = new Thread(new Runnable()
        {
            @Override
            public void run()
            {
                int i = 0;
                while(!stopRequested())
                {
                    ++i;
                }
            }
        });
        //啟動(dòng)線程
        backgroundThread.start();
        
        //休眠1秒
        try
        {
            TimeUnit.SECONDS.sleep(1);
        }
        catch (InterruptedException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        requestStop();
    }
    
    @Test
    public void test2()
    {
        Thread backgroundThread = new Thread(new Runnable()
        {
            @Override
            public void run()
            {
                int i = 0;
                System.out.println("這里使用最新的stopRequested2值");
                while(!stopRequested2)
                {
                    ++i;
                }
            }
        });
        
        //啟動(dòng)線程
        backgroundThread.start();
        
        //停下1s之后執(zhí)行變量修改程序
        try
        {
            TimeUnit.SECONDS.sleep(1);
        }
        catch (InterruptedException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //修改變量
        stopRequested2 = true;
    }
    
    
    public static void main(String[] args) throws InterruptedException
    {
        Thread backgroundThread = new Thread(new Runnable()
        {
            @Override
            public void run()
            {
                int i = 0;
                System.out.println(stopRequested); //false
                //這里停不下來(lái)是因?yàn)橹骶€程對(duì)stopRequest進(jìn)行修改的時(shí)候，這個(gè)線程并不可見(jiàn)
                while(!stopRequested)
                {
                    ++i;
                }
            }
        });
        //啟動(dòng)線程
        backgroundThread.start();
        
        //休眠1秒
        TimeUnit.SECONDS.sleep(1);
        stopRequested = true;
    }
}

This main method will never stop, and the other two are from two different angles Synchronization methods are given

In short: when multiple threads share variable data, each thread that reads or writes data must perform synchronization.