Java - ThreadGroup isDestroyed() Method with Examples

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Description

The Java ThreadGroup isDestroyed() method tests if this thread group has been destroyed.

Declaration

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

public boolean isDestroyed()

Parameters

NA

Return Value

This method returns true if this object is destroyed.

Exception

NA

Example 1

The following example shows the usage of ThreadGroup isDestroyed() method in case of a single ThreadGroup object. We've created a ThreadGroup object and assigned it a name. Then we've created two threads using the threadgroup object created earlier. Using isDestroyed() method, we're getting the status of the parent of this thread group object.

package com.tutorialspoint;

public class ThreadGroupDemo implements Runnable {
   public static void main(String[] args) {
      ThreadGroupDemo tg = new ThreadGroupDemo();
      tg.start();
   }

   public void start() {
      try {     
         // create a ThreadGroup
         ThreadGroup threadGroup = new ThreadGroup("ThreadGroup");

         // create a thread
         Thread t1 = new Thread(threadGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         // create another thread
         Thread t2 = new Thread(threadGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();

         // returns the status of thread group
         boolean isDestroyed = threadGroup.isDestroyed();
         System.out.println("Status of the threadGroup = " + isDestroyed);

         // 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 < 4;i++) {
         i++;
         try {
			Thread.sleep(50);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
      }
      System.out.println(Thread.currentThread().getName() + " finished executing.");
   }
} 

Output

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

Starting Thread-0...
Starting Thread-1...
Status of the threadGroup = false
Thread-1 finished executing.
Thread-0 finished executing.

Example 2

The following example shows the usage of ThreadGroup isDestroyed() method in case of multiple ThreadGroup objects. We've created a ThreadGroup object and assigned it a name. As next, we've created a child ThreadGroup object. Then we've created two threads using the threadgroup objects created earlier. Using isDestroyed() method, we're printing status each threadgroup object.

package com.tutorialspoint;

public class ThreadGroupDemo implements Runnable {
   public static void main(String[] args) {
      ThreadGroupDemo tg = new ThreadGroupDemo();
      tg.start();
   }

   public void start() {
      try {     
         // create a parent ThreadGroup
         ThreadGroup pThreadGroup = new ThreadGroup("parent ThreadGroup");
		 
         // create a child ThreadGroup for parent ThreadGroup
         ThreadGroup cThreadGroup = new ThreadGroup(pThreadGroup, "child ThreadGroup");

         // create a thread
         Thread t1 = new Thread(pThreadGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         // create another thread
         Thread t2 = new Thread(cThreadGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();

         // returns the status of thread group
         System.out.println("Status of pThreadGroup = " + pThreadGroup.isDestroyed());
         System.out.println("Status of cThreadGroup = " + cThreadGroup.isDestroyed());
         
         // 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 < 4;i++) {
         i++;
         try {
			Thread.sleep(50);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
      }
      System.out.println(Thread.currentThread().getName() + " finished executing.");
   }
} 

Output

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

Starting Thread-0...
Starting Thread-1...
Status of pThreadGroup = false
Status of cThreadGroup = false
Thread-1 finished executing.
Thread-0 finished executing.

Example 3

The following example shows the usage of ThreadGroup isDestroyed() method in case of child and grandchild ThreadGroup objects. We've created a ThreadGroup object and assigned it a name. As next, we've created a child ThreadGroup object. Then we've created two threads using the child and grandchild threadgroup objects created earlier. Using isDestroyed() method, we're printing status of each threadgroup object.

package com.tutorialspoint;

public class ThreadGroupDemo implements Runnable {
   public static void main(String[] args) {
      ThreadGroupDemo tg = new ThreadGroupDemo();
      tg.start();
   }

   public void start() {
      try {     
         // create a parent ThreadGroup
         ThreadGroup pThreadGroup = new ThreadGroup("Parent ThreadGroup");
		 
         // create a child ThreadGroup for parent ThreadGroup
         ThreadGroup cThreadGroup = new ThreadGroup(pThreadGroup, "Child ThreadGroup");
		 
         // create a grandchild ThreadGroup for parent ThreadGroup
         ThreadGroup gThreadGroup = new ThreadGroup(cThreadGroup, "GrandChild ThreadGroup");

         // create a thread
         Thread t1 = new Thread(cThreadGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         // create another thread
         Thread t2 = new Thread(gThreadGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();
            
         // returns the status of thread group
         System.out.println("Status of pThreadGroup = " + pThreadGroup.isDestroyed());
         System.out.println("Status of cThreadGroup = " + cThreadGroup.isDestroyed());
         System.out.println("Status of gThreadGroup = " + gThreadGroup.isDestroyed());
		 
         // 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 < 4;i++) {
         i++;
         try {
			Thread.sleep(50);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
      }
      System.out.println(Thread.currentThread().getName() + " finished executing.");
   }
} 

Output

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

Starting Thread-0...
Starting Thread-1...
Status of pThreadGroup = false
Status of cThreadGroup = false
Status of gThreadGroup = false
Thread-0 finished executing.
Thread-1 finished executing.