java.lang.ThreadGroup.isDestroyed() 方法测试该线程组是否已销毁。

声明

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

public boolean isDestroyed()

参数

• NA

返回值

如果该对象被销毁此方法返回true。

异常

• NA

例子

下面的例子显示java.lang.ThreadGroup.isDestroyed()方法的使用。

package com.yiibai;

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();

         // block until the other threads finish
         t1.join();
         t2.join();

         try {
            // child group destroyed
            if (!cGroup.isDestroyed()) {
               cGroup.destroy();
            }
            else {
               System.out.println(cGroup.getName() + " destroyed");
            }
         } 
         catch(IllegalThreadStateException ex) {
            System.out.println(cGroup.getName() + " is empty: " + 
            ex.toString());
         }

         try {
            // parent group destroyed
            if (!pGroup.isDestroyed()) {
               pGroup.destroy();
            }
            else {
               System.out.println(pGroup.getName() + " destroyed");
            }
         }
         catch(IllegalThreadStateException ex) {
            System.out.println(pGroup.getName() + " is empty: " + 
            ex.toString());
         }

      }
      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.");
   }
} 

让我们来编译和运行上面的程序，这将产生以下结果：

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