Java多线程学习:Join()

时间：2019-12-20 21:05:18 阅读：101 评论：0 收藏：0 [点我收藏+]

标签：过多 art begin closed 方法注释 opened static ima 就是

方法join的作用是使所属的线程对象x正常执行run()方法中的任务，而使当前线程Z进行无限期的阻塞，等待线程X销毁后再继续执行线程Z后面的代码。一般用于子线程先执行完毕再继续执行主线程的情况。

但是join方法后面的代码会不会提前执行呢？看下面的代码

 1 public class ThreadA extends Thread {
 2 
 3     private ThreadB threadB;
 4 
 5     public ThreadA(ThreadB threadB) {
 6         super();
 7         this.threadB = threadB;
 8     }
 9 
10     @Override
11     public void run() {
12         synchronized (threadB) {
13             System.out.println("begin A ThreadName=" + Thread.currentThread().getName());
14             try {
15                 Thread.sleep(5000);
16             } catch (InterruptedException e) {
17                 e.printStackTrace();
18             }
19             System.out.println("end A ThreadName=" + Thread.currentThread().getName());
20         }
21     }
22 
23 
24 }

View Code

 1 public class ThreadB extends Thread{
 2     @Override
 3     public void run() {
 4         System.out.println("begin B ThreadName=" + Thread.currentThread().getName());
 5         try {
 6             Thread.sleep(5000);
 7         } catch (InterruptedException e) {
 8             e.printStackTrace();
 9         }
10         System.out.println("end B ThreadName=" + Thread.currentThread().getName());
11     }
12 }

View Code

 1 public class Run {
 2     public static void main(String[] args) throws InterruptedException {
 3         ThreadB threadB = new ThreadB();
 4         ThreadA threadA = new ThreadA(threadB);
 5         threadA.start();
 6         threadB.start();
 7         threadB.join(2000);
 8         System.out.println("main thread");
 9 
10     }
11 }