多线程7---volatile关键字,刷新线程工作空间内存到主内存中去,即保持同步

 1 public class RunThread extends Thread{
 2     private volatile  boolean isRunning = true;
 3     public void setRunning(boolean isRunning) {
 4         System.out.println(Thread.currentThread().getName()+"线程setRunning");
 5         this.isRunning = isRunning;
 6     }
 7 
 8     public void run(){
 9         System.out.println(Thread.currentThread().getName()+"进入run方法...");
10         while(isRunning) {
11             //System.out.println(Thread.currentThread().getName()+"线程isRunning");
12         }
13         System.out.println(Thread.currentThread().getName()+"线程终止");
14     }
15 
16     public static void main(String[] args) throws Exception {
17         RunThread rt = new RunThread();
18         rt.start();
19         Thread.sleep(3000);
20         rt.setRunning(false);
21         System.out.println(Thread.currentThread().getName()+"线程isRunning值被设置成false");
22         Thread.sleep(100);
23         System.out.println(Thread.currentThread().getName()+"::"+rt.isRunning);
24     }
25     /* 不加volatile关键字, 主内存中的isRunning不会被刷新,永远都是true.所以线程不会终止,加了会把rt线程的工作内存变量刷新到主内存
26      * Thread-0进入run方法...
27         main线程setRunning
28         main线程isRunning值被设置成false
29         main::false
30      */
31 }