Java.lang.ThreadGroup.activeCount() Method
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Description
The java.lang.ThreadGroup.activeCount() method returns an estimate of the number of active threads in this thread group.
Declaration
Following is the declaration for java.lang.ThreadGroup.activeCount() method
public int activeCount()
Parameters
NA
Return Value
This method returns an estimate of the number of active threads in this thread group and in any other thread group that has this thread group as an ancestor.
Exception
NA
Example
The following example shows the usage of java.lang.ThreadGroup.activeCount() 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(); // display the number of active threads System.out.println("Active threads in \"" + pGroup.getName() + "\" = " + pGroup.activeCount()); // 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<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... Active threads in "Parent ThreadGroup" = 2 Thread-0 finished executing. Thread-1 finished executing.
java_lang_threadgroup.htm
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