Question 16, Practice Exam from K&B Book

[Konrad Till]

Can anybody explain me, why does this code print also "0"?
(the code is slightly modified by me - added the println statement)
It looks like 0 > 0 returns true. I'm quite confused about that.

public class Stubborn implements Runnable{
	static Thread t1;
	static int x = 5;
	public void run(){
		if(Thread.currentThread().getId() == t1.getId()) shove();
		else push();
	}
	static synchronized void push(){shove();}
	static void shove(){
		synchronized(Stubborn.class){
			System.out.print(x-- + " ");
			try{ Thread.sleep(2000); } catch (Exception e) {;}
			System.out.println("\nbefore if statement, x is: " + x);
			if(x > 0) push();
		}
	}
	public static void main(String [] args){
		t1 = new Thread(new Stubborn());
		t1.start();
		new Thread(new Stubborn()).start();
	}
}

[dennis deems]

Try printing the current thread Id just before x is printed, and see if that helps to clear things up.

[Konrad Till]

Thanks! I totally forgot about that statement ;)