Java Thread enumerate() method

The enumerate() method of thread class is used to copy every active thread's thread group and its subgroup into the specified array. This method calls the enumerate method with the tarray argument.

This method uses the activeCount method to get an estimate of how big the array should be. If the length of the array is too short to hold all the threads, the extra threads are silently ignored.

Syntax

Parameter

tarray: This method is an array of Thread objects to copy to.

Return

This method returns the number of threads put into the array.

Example

public class JavaEnumerateExp extends Thread 
{
    JavaEnumerateExp(String threadname, ThreadGroup tg)
    {
        super(tg, threadname);
        start();
    }
    public void run()
    {
        for (int i = 0; i < 5; i++) 
        {
            try
            {
                Thread.sleep(10);
            }	
            catch (InterruptedException ex) {
                System.out.println("Exception encounterted");}
        }
        System.out.println(Thread.currentThread().getName() +" completed executing");
    }
    public static void main(String arg[]) throws InterruptedException,SecurityException
    {
        // creating the ThreadGroup
        ThreadGroup g1 = new ThreadGroup("Parent thread");
        // creating a child ThreadGroup for parent ThreadGroup
        ThreadGroup g2 = new ThreadGroup(g1, "child thread");
 
        // creating a thread 
        JavaEnumerateExp t1 = new JavaEnumerateExp("Thread-1", g1);
        System.out.println("Starting of Thread-1");
        // creating another thread 
        JavaEnumerateExp t2 = new JavaEnumerateExp("Thread-2", g1);
        System.out.println("Starting of Thread-2");
 
        // returns the number of threads put into the array
        Thread[] group = new Thread[g1.activeCount()];
        int count = g1.enumerate(group);
        
        // prints active threads
        for (int i = 0; i < count; i++) 
        {
            System.out.println(group[i].getName() + " found");
        }
    }
}

Test it Now

Output:

Starting of Thread-1
Starting of Thread-2
Thread-1 found
Thread-2 found
Thread-1 completed executing
Thread-2 completed executing

Next TopicMultithreading Java

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