// tasks/Daemons.java

// (c)2016 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://mindviewinc.com/Books/OnJava/ for more book information.

// Daemon threads spawn other daemon threads

import java.util.concurrent.*;

class Daemon implements Runnable {

private Thread[] t = new Thread[10];

@Override

public void run() {

for(int i = 0; i < t.length; i++) {

t[i] = new Thread(new DaemonSpawn());

t[i].start();

System.out.print("DaemonSpawn " + i + " started, ");

}

for(int i = 0; i < t.length; i++)

System.out.print("t[" + i + "].isDaemon() = " +

t[i].isDaemon() + ", ");

while(true)

Thread.yield();

}

}

class DaemonSpawn implements Runnable {

@Override

public void run() {

while(true)

Thread.yield();

}

}

public class Daemons {

public static void

main(String[] args) throws Exception {

Thread d = new Thread(new Daemon());

d.setDaemon(true);

d.start();

System.out.print(

"d.isDaemon() = " + d.isDaemon() + ", ");

// Allow the daemon threads to

// finish their startup processes:

TimeUnit.SECONDS.sleep(1);

}

}

/* Output:

d.isDaemon() = true, DaemonSpawn 0 started, DaemonSpawn 1

started, DaemonSpawn 2 started, DaemonSpawn 3 started,

DaemonSpawn 4 started, DaemonSpawn 5 started, DaemonSpawn 6

started, DaemonSpawn 7 started, DaemonSpawn 8 started,

DaemonSpawn 9 started, t[0].isDaemon() = true,

t[1].isDaemon() = true, t[2].isDaemon() = true,

t[3].isDaemon() = true, t[4].isDaemon() = true,

t[5].isDaemon() = true, t[6].isDaemon() = true,

t[7].isDaemon() = true, t[8].isDaemon() = true,

t[9].isDaemon() = true,

*/