Java多线程中的join方法

新建一个Thread,代码如下:

 package com.thread.test;

 public class MyThread extends Thread {
     private String name;
     public MyThread(String name) {
         this.name = name;
     }
     @Override
     public void run() {
         for (int i = 0; i < 100; i++) {
             System.out.println(name+"["+i+"]");
         }
         super.run();
     }
 }

之后新建测试类,代码如下:

 package com.thread.test;
 /*
  * 0-50执行的是主线程,50-100执行的是A线程,并且将A线程完全执行完后才继续执行主线程
  */
 public class ThreadDemo{
     public static void main(String[] args) {
         MyThread t = new MyThread("A");
         t.start();
         for (int i = 0; i < 100; i++) {
             if (i>50) {
                 try {
                     t.join();
                 } catch (InterruptedException e) {
                     e.printStackTrace();
                 }
             }
             System.out.println("主线程"+"["+i+"]");
         }
     }
 }

下面是Java Platform SE8 API中对Thread中Join方法的解释:

public final void join(long millis)
                throws InterruptedExceptionWaits at most millis milliseconds for this thread to die. A timeout of 0 means to wait forever.
This implementation uses a loop of this.wait calls conditioned on this.isAlive. As a thread terminates the this.notifyAll method is invoked. It is recommended that applications not use wait, notify, or notifyAll on Thread instances.

Parameters:
millis - the time to wait in milliseconds
Throws:
IllegalArgumentException - if the value of millis is negative
InterruptedException - if any thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown.