Java ThreadGroup enumerate()方法

java.lang.ThreadGroup.enumerate(Thread[] list, boolean recurse) 方法复制到指定的数组该线程组中的所有活动线程。如果递归标志为true，也包括引用在此线程的子组的所有活动线程。

如果数组太小而无法保持所有线程，多出来的线程忽略。

1 语法

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

2 参数

list ： 这是一个数组，用于放置线程列表。

recurse ： 这是一个标志，指示是否也包括在线程组是该线程组的子组线程。

3 返回值

此方法返回放入数组中的线程的数目。

4 示例 

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java ThreadGroup enumerate()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();
            
         // returns the number of threads put into the array with flag as true
         Thread[] list = new Thread[pGroup.activeCount()];
         int count = pGroup.enumerate(list, true);
         for (int i = 0; i < count; i++) {
            System.out.println("Thread " + list[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.");
   }
} 

输出结果为：

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