Java.lang.ThreadGroup.isDestroyed() 方法

描述

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

声明

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

public boolean isDestroyed()

参数

NA

返回值

如果此对象被销毁，则此方法返回 true。

异常

NA

示例

下面的例子展示了 java.lang.ThreadGroup.isDestroyed() 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();

         // 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...
Thread-0 finished executing.
Thread-1 finished executing.