以上答案都是好的。下面是一个简单的小代码片段，以说明两者的区别。在setDaemon中分别尝试true和false值。

public class DaemonTest {
    
    public static void main(String[] args) {
        new WorkerThread().start();

        try {
            Thread.sleep(7500);
        } catch (InterruptedException e) {
            // handle here exception
        }

        System.out.println("Main Thread ending") ;
    }

}

class WorkerThread extends Thread {
    
    public WorkerThread() {
        // When false, (i.e. when it's a non daemon thread),
        // the WorkerThread continues to run.
        // When true, (i.e. when it's a daemon thread),
        // the WorkerThread terminates when the main 
        // thread or/and user defined thread(non daemon) terminates.
        setDaemon(true); 
    }
    
    public void run() {
        int count = 0;

        while (true) {
            System.out.println("Hello from Worker "+count++);

            try {
                sleep(5000);
            } catch (InterruptedException e) {
                // handle exception here
            }
        }
    }
}

守护线程就像一个普通的线程，除了JVM只会在其他非守护线程不存在时关闭。守护进程线程通常用于为应用程序执行服务。

java线程中的用户线程与守护线程

守护进程的线程

这些线程在Java中是低优先级的线程，在后台运行以执行诸如垃圾收集之类的任务。Java中的守护线程也是一个服务提供者线程，它向用户线程提供服务。

用户线程

这些线程是高优先级线程。JVM将等待任何用户线程在终止它之前完成它的任务

“请记住用户和守护线程都包装在操作系统线程上”

最近OpenJdk在Loom项目中提出了虚拟线程(它们也是基于用户的)，你可以在这里找到更多关于Java虚拟机线程的纤维和延续。

守护线程是在进程的其他非守护线程仍在运行时在后台运行的线程。因此，当所有非守护进程线程完成时，守护进程线程将终止。非守护进程线程的一个例子是运行Main的线程。 通过在线程启动之前调用setDaemon()方法，将线程设置为守护进程

更多参考:Java中的守护进程线程

守护进程： d（isk） a（nd） e（xecution） mon（itor） or or from de（vice） mon（itor）

Daemon(计算)的定义:

处理打印假脱机和文件传输等服务请求的后台进程，在不需要时处于休眠状态。

——来源:牛津词典英文版

Java中的守护线程是什么?

Daemon threads can shut down any time in between their flow, Non-Daemon i.e. user thread executes completely. Daemon threads are threads that run intermittently in the background as long as other non-daemon threads are running. When all of the non-daemon threads complete, daemon threads terminates automatically. Daemon threads are service providers for user threads running in the same process. The JVM does not care about daemon threads to complete when in Running state, not even finally block also let execute. JVM do give preference to non-daemon threads that is created by us. Daemon threads acts as services in Windows. The JVM stops the daemon threads when all user threads (in contrast to the daemon threads) are terminated. Hence daemon threads can be used to implement, for example, a monitoring functionality as the thread is stopped by the JVM as soon as all user threads have stopped.

Java中的守护线程是指运行在后台的线程，主要由JVM创建，用于执行后台任务，如垃圾收集和其他家政任务。

注意事项:

Any thread created by main thread, which runs main method in Java is by default non daemon because Thread inherits its daemon nature from the Thread which creates it i.e. parent Thread and since main thread is a non daemon thread, any other thread created from it will remain non-daemon until explicitly made daemon by calling setDaemon(true). Thread.setDaemon(true) makes a Thread daemon but it can only be called before starting Thread in Java. It will throw IllegalThreadStateException if corresponding Thread is already started and running.

Java中守护线程与非守护线程的区别:

1) JVM在存在之前不会等待任何守护线程完成。

2)当JVM终止时，守护线程与用户线程被区别对待，最终块不被调用，堆栈不受伤，JVM只是退出。