Java ThreadGroup parentOf()方法

java.lang.ThreadGroup.parentOf() 方法测试此线程组是否为线程组参数或其祖先线程组中的一个。

1 语法

public final boolean parentOf(ThreadGroup g)

2 参数

g ： 这是一个线程组。

3 返回值

如果该线程组是线程组参数或其祖先线程组之一此方法返回true;否则为false。

4 示例 

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java ThreadGroup parentOf()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();
            
         // determine which ThreadGroup is parent
         boolean isParent = pGroup.parentOf(cGroup);
         System.out.println(pGroup.getName() + " is the parent of "
         + cGroup.getName() + "? " + isParent);

         isParent = cGroup.parentOf(pGroup);
         System.out.println(cGroup.getName() + " is the parent of "
         + pGroup.getName() + "? " + isParent);

         // 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.
Parent ThreadGroup is the parent of Child ThreadGroup? true
Child ThreadGroup is the parent of Parent ThreadGroup? false
Thread-1 finished executing.