Java multithreading - thread scheduling (daemon thread)

The daemon thread is basically the same as the ordinary thread writing method. You can set it as a daemon thread by calling the method setDaemon(true) of the thread object.

Daemon threads are rarely used, but not useless. For example, JVM garbage collection, memory management and other threads are daemon threads. There is also the database connection pool used when doing database applications. The connection pool itself also contains many background threads to monitor the number of connections, timeout, status, and so on.

Detailed description of the setDaemon method:
public final void setDaemon(boolean on): Mark the thread as a daemon thread or a user thread. When the running threads are all daemon threads, the Java virtual machine exits.

This method must be called before starting the thread.

The method first calls the thread's checkAccess method without any parameters. This may throw a SecurityException (in the current thread).

Parameters: 
on - if true, marks the thread as a daemon thread. 
Throws: 
IllegalThreadStateException - if the thread is active. 
SecurityException - if the current thread cannot modify the thread. 
See also: 
isDaemon(), checkAccess()

package cn.thread;

/**
 * Thread scheduling (daemon thread)
 *
 * @author Lin Jiqin
 * @version 1.0 2013-7-24 09:30:42 AM
  */ 
public  class ThreadDaemon {
    
    public static void main(String[] args) {
           ThreadDaemon thread=new ThreadDaemon();
           Thread t1 = thread.new MyThread1(); 
           Thread t2 = new Thread(thread.new MyRunnable()); 
           t2.setDaemon( true ); // Set as a daemon thread
           
           t2.start();
           t1.start();
    }
    
    class MyThread1 extends Thread {
        public void run() {
            for (int i = 0; i < 5; i++) {
                System.out.println( "Thread 1" + i + "execution!" );
                 try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace ();
                }
            }
        }
    }

    class MyRunnable implements Runnable {
        public void run() {
            for (long i = 0; i < 9999999L; i++) { 
                System.out.println( "Background thread" + i + "execution!" ); 
                 try {
                        Thread.sleep(7); 
                } catch (InterruptedException e) { 
                        e.printStackTrace ();
                }
        }
        }
    }
}

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