Java.lang.ThreadGroup.destroy() Method

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Description

The java.lang.ThreadGroup.destroy() method destroys this thread group and all of its subgroups. This thread group must be empty, indicating that all threads that had been in this thread group have since stopped.

Declaration

Following is the declaration for java.lang.ThreadGroup.destroy() method

public final void destroy()

Parameters

  • NA

Return Value

This method does not return any value.

Exception

  • IllegalThreadStateException -- if the thread group is not empty or if the thread group has already been destroyed.

  • SecurityException -- if the current thread cannot modify this thread group.

Example

The following example shows the usage of java.lang.ThreadGroup.destroy() method.

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();

         // child group destroyed
         cGroup.destroy();
         System.out.println(cGroup.getName() + " destroyed");
 
         // parent group destroyed
         pGroup.destroy();
         System.out.println(pGroup.getName() + " destroyed");

      }
      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.");
   }
} 

Let us compile and run the above program, this will produce the following result:

Starting Thread-0...
Starting Thread-1...
Thread-0 finished executing.
Thread-1 finished executing.
Child ThreadGroup destroyed
Parent ThreadGroup destroyed



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