Daemon Thread In Java | Daemon Thread In Java In Hindi | Daemon Thread In Java Program

Daemon Thread in Java

Daemon thread in java is a service provider thread that provides services to the user thread. Its life depend on the mercy of user threads i.e. when all the user threads dies, JVM terminates this thread automatically.

There are many java daemon threads running automatically e.g. gc, finalizer etc.

You can see all the detail by typing the jconsole in the command prompt. The jconsole tool provides information about the loaded classes, memory usage, running threads etc.

Fig:  Daemon Thread 

Why JVM terminates the daemon thread if there is no user thread?

The sole purpose of the daemon thread is that it provides services to user thread for background supporting task. If there is no user thread, why should JVM keep running this thread. That is why JVM terminates the daemon thread if there is no user thread.

Simple example of Daemon thread in java

File: MyThread.java

  public class TestDaemonThread1 extends Thread{  

    public void run(){  

  if(Thread.currentThread().isDaemon()){//checking for daemon thread  

   System.out.println("daemon thread work");  

  }  

  else{  

  System.out.println("user thread work");  

  }  

   }  

   public static void main(String[] args){  

  TestDaemonThread1 t1=new TestDaemonThread1();//creating thread  

  TestDaemonThread1 t2=new TestDaemonThread1();  

  TestDaemonThread1 t3=new TestDaemonThread1();  

     

  t1.setDaemon(true);//now t1 is daemon thread  

      

  t1.start();//starting threads  

  t2.start();  

  t3.start();  

 }  

   }  

Output:

daemon thread work

user thread work

user thread w