Java多线程中关于join方法的使用实例解析

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。