Java ThreadGroup parentOf() method

The parentOf() method of ThreadGroup class tests if the thread group is either the argument of thread group or one of its ancestor thread groups.

Syntax

Parameter

g: It is the thread group

Return

It returns true if the invoking thread is the parent of group. Otherwise, it returns false.

Example

class NewThread extends Thread 
{
    NewThread(String threadname, ThreadGroup tg)
    {
        super(tg, threadname);
    }
public void run()
    {
        for (int i = 0; i < 5; i++) 
        {
            try
            {
                Thread.sleep(10);
            }
            catch (InterruptedException ex){
            }
        }
        System.out.println(Thread.currentThread().getName() + " completed executing");
    }
} 
public class ThreadGroupParentOfExp 
{
    public static void main(String arg[]) throws InterruptedException,
        SecurityException, Exception
    {
        // creating the thread group
        ThreadGroup g1 = new ThreadGroup("Parent thread");
        ThreadGroup g2 = new ThreadGroup(g1, "Child thread");
 
        // creating a thread 
        NewThread t1 = new NewThread("Thread-1", g1);
        System.out.println(t1.getName()+" starts");
        t1.start();
        
        // creating another thread 
        NewThread t2 = new NewThread("Thread-2", g1);
        System.out.println(t2.getName()+" starts");
        t2.start();
        
        // checking who is parent thread
        boolean isParent = g2.parentOf(g1);
        System.out.println(g2.getName() + " is the parent of " + g1.getName() +": "+ isParent);
        
        isParent = g1.parentOf(g2);
        System.out.println(g1.getName() + " is the parent of " + g2.getName() +": "+ isParent);
    }
}

Test it Now

Output:

Thread-1 starts
Thread-2 starts
Child thread is the parent of Parent thread: false
Parent thread is the parent of Child thread: true
Thread-1 completed executing
Thread-2 completed executing

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