Java.lang.ThreadGroup.enumerate() 方法

描述

java.lang.ThreadGroup.enumerate(ThreadGroup[] list, boolean recurse) 方法将对该线程组中每个活动子组的引用复制到指定的数组中。 如果 recurse 标志为真，则还包括对子组的所有活动子组的引用等。

声明

以下是 java.lang.ThreadGroup.enumerate() 方法的声明。

public int enumerate(ThreadGroup[] list, boolean recurse)

参数

• list − 这是一个用于放置线程组列表的数组。

• recurse − 这是一个标志，指示是否递归枚举所有包含的线程组。

返回值

该方法返回放入数组的线程组数。

异常

SecurityException − 如果当前线程没有权限枚举这个线程组。

示例

下面的例子展示了 java.lang.ThreadGroup.enumerate() 方法的使用。

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();
            
         /* returns the number of thread groups put into the array with
         flag as true */
         ThreadGroup[] grpList = new ThreadGroup[pGroup.activeGroupCount()];
         int count = pGroup.enumerate(grpList, true);
         for (int i = 0; i < count; i++) {
            System.out.println("ThreadGroup" + grpList[i].getName() + " found");
         }

         // 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.");
   }
} 

让我们编译并运行上面的程序，这将产生下面的结果 −

Starting Thread-0...
Starting Thread-1...
ThreadGroup Child ThreadGroup found
Thread-0 finished executing.
Thread-1 finished executing.