Java Java.lang.ThreadGroup.parentOf()用法及代碼示例

描述

這個java.lang.ThreadGroup.parentOf()方法測試此線程組是線程組參數還是其祖先線程組之一。

聲明

以下是聲明java.lang.ThreadGroup.parentOf()方法

public final boolean parentOf(ThreadGroup g)

參數

g- 這是一個線程組。

返回值

如果此線程組是線程組參數或其祖先線程組之一，則此方法返回 true；否則為假。

異常

NA

示例

下麵的例子展示了 java.lang.ThreadGroup.parentOf() 方法的用法。

package com.tutorialspoint;

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.");
   }
}

讓我們編譯並運行上麵的程序，這將產生以下結果 -

Starting Thread-0...
Starting Thread-1...
Parent ThreadGroup is the parent of Child ThreadGroup? true
Thread-0 finished executing.
Child ThreadGroup is the parent of Parent ThreadGroup? false
Thread-1 finished executing.