Synchronization and Lock Confusion - Enthuware Sample

[Arhaan Singhania]

Hi,

I am trying to solve mocks in enthuware regarding concurrency. Here is the code given below

public class Test extends Thread
{
 static int x, y;
 public synchronized void setX(int i) { x++; }
 public synchronized void setY(int j) {y++; }
 public void setXY(int i, int j) { setX(i); setY(j); }
 public boolean testXY() { return x != y;}
 public void run(){  setXY(1, 2); System.out.println(testXY()); }
 public static void main(String[] args)
 {
   new Test().start();
   new Test().start();
 }
}

The options are
True
False

The answer is b. My first question is that, as these are two different instances over which a non-synchronized
method is invoked which in turn invokes the two synchronized methods simultaneously. My first question is that,
as they are invoked on two different instances, so calling of the synchronized methods should not block each other.
Is that correct? Will these two thread executing parallel or one will be in the runnable pool. Please sorry for the stupid
questions, but really confused in threads.

Though seems like my first assumption is incorrect. Please help.

Thanks,
Arhaan

[Ankit Garg]

Yes since there are two instances here, the two threads can execute setX and setY method at the same time. Now you've only written the options and not the actual question so I can't say whether your answer is right or not...

[Arhaan Singhania]

Thanks Ankit. I have cleared the confusion i was facing. Thanks a ton.
Arhaan