Count Active Thread in JAVA

In this tutorial, we are using activeCount() method of thread to count the current active threads.

Thread activeCount() :

Thread class provides you to check the current active thread by providing activeCount() method.

activeCount() :  This method returns the total number of active threads in the current thread group.

Example :

class ThreadCount implements Runnable {
	Thread th;
	String str;

	public ThreadCount(String str) {
		this.str = str;
		th = new Thread(this);
		th.start();
	}

	public void run() {
		try {
			Thread.sleep(500);

		} catch (InterruptedException e) {

			e.printStackTrace();
		}
	}
}

class ThreadActiveCount {

	public static void main(String args[]) {
		new ThreadCount("A");
		new ThreadCount("B");
		new ThreadCount("C");
		/* Thread.activeCount() returns active threads */
		System.out
				.println("Number of active threads : " + Thread.activeCount());
	}
}

Output :

Number of active threads : 4

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