How do I check if a thread is a daemon thread?

You can test if a thread is a daemon thread or a user thread by calling the isDaemon() method of the Thread class. If it return true then the thread is a daemon thread, otherwise it is a user thread.

package org.kodejava.example.lang;

public class ThreadCheckDaemon implements Runnable {
    public void run() {
        System.out.println("Running [" +
            Thread.currentThread().getName() + "]");
    }

    public static void main(String[] args) {
        Thread t1 = new Thread(new ThreadCheckDaemon(), "FirstThread");
        Thread t2 = new Thread(new ThreadCheckDaemon(), "SecondThread");

        t1.setDaemon(true);
        t1.start();
        t2.start();

        if (t1.isDaemon()) {
            System.out.format("%s is a daemon thread.%n", t1.getName());
        } else {
            System.out.format("%s is a user thread.%n", t1.getName());
        }

        if (t2.isDaemon()) {
            System.out.format("%s is a daemon thread %n", t2.getName());
        } else {
            System.out.format("%s is a user thread %n", t2.getName());
        }
    }
}

The code snippet print the following output:

Running [SecondThread]
Running [FirstThread]
FirstThread is a daemon thread.
SecondThread is a user thread 

Wayan Saryada

Programmer, runner, recreational diver, live in the island of Bali, Indonesia. Mostly programming in Java, creating web based application with Spring Framework, Hibernate / JPA.

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