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[Java教程]浅谈Java多线程中的join方法

先上代码

新建一个Thread,代码如下:

 1 package com.thread.test; 2  3 public class MyThread extends Thread { 4   private String name; 5   public MyThread(String name) { 6     this.name = name; 7   } 8   @Override 9   public void run() {10     for (int i = 0; i < 100; i++) {11       System.out.println(name+"["+i+"]");12     }13     super.run();14   }15 }

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.

先上代码

新建一个Thread,代码如下:

 1 package com.thread.test; 2  3 public class MyThread extends Thread { 4   private String name; 5   public MyThread(String name) { 6     this.name = name; 7   } 8   @Override 9   public void run() {10     for (int i = 0; i < 100; i++) {11       System.out.println(name+"["+i+"]");12     }13     super.run();14   }15 }

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.

 我自己的理解就是会强行进入使用join方法的线程,其他线程等待该线程完全执行完后才会进来。