Java ThreadGroup getParent()方法

java.lang.ThreadGroup.getParent() 方法返回该线程组的父级。

1 语法

public final ThreadGroup getParent()

2 参数

无

3 返回值

此方法返回该线程组的父级。顶层线程组是其父级是null的线程组。

4 示例 

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java ThreadGroup getParent()方法
 */
import java.lang.*;

public class ThreadGroupDemo implements Runnable
{
   public static void main(String[] args) {
      ThreadGroupDemo tg = new ThreadGroupDemo();
      tg.func();
   }

   public void func() {
      try {     
         // create a parent ThreadGroup
         ThreadGroup pGroup = new ThreadGroup("Parent ThreadGroup");
    
         // create a child ThreadGroup for parent ThreadGroup
         ThreadGroup cGroup = new ThreadGroup(pGroup, "Child ThreadGroup");

         // create a thread
         Thread t1 = new Thread(pGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         // create another thread
         Thread t2 = new Thread(cGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();

         // prints the parent ThreadGroup of both parent and child threads
         System.out.println("ParentThreadGroup for " +
         pGroup.getName() + " is " + pGroup.getParent().getName());
         System.out.println("ParentThreadGroup for " +
         cGroup.getName() + " is " + cGroup.getParent().getName());
         
         // block until the other threads finish
         t1.join();
         t2.join();
      }
      catch (InterruptedException ex) {
         System.out.println(ex.toString());
      }
   }

   // implements run()
   public void run() {

      for(int i = 0;i < 1000;i++) {
         i++;
      }
      System.out.println(Thread.currentThread().getName() + 
      " finished executing.");
   }
} 

输出结果为：

Starting Thread-0...
Starting Thread-1...
Thread-0 finished executing.
ParentThreadGroup for Parent ThreadGroup is main
ParentThreadGroup for Child ThreadGroup is Parent ThreadGroup
Thread-1 finished executing.