先上代码

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.

先上代码

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.

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。