Thread Operation - daemon thread

Question

What will be the output of the following program (with explaination)?
public class A extends Thread {
A() {
setDaemon(true);
public void run() {
(new B()).start();
try{
Thread.sleep(60000);
} catch (InterruptedException x) {}
System.out.println("A done");
class B extends Thread{
public void run() {
try{
Thread.sleep(60000);
} catch (InterruptedException x) {}
System.out.println("B done");
public static void main(String[] args) {
(new A()).start();
}

Answer 1

If you consult the documentation for Thread.setDaemon to see what a daemon thread means; and the docs for the constructors of Thread to see what the default daemon status is, then you will understand why this program prints nothing.
Now if you moved those prints ahead of the sleeps it might print something but it need not - all depends on scheduling.