Question on synchronisation

[Lavanya Raguram]

wat will be the answer for this question? pls explain

public class SyncTest {
private int x;
private int y;
private synchronized void setX( int i ) { x = i; }
private synchronized void setY( int i ) { y = i; }
public void setXY( int i ) { setX(i); setY(i); }
public synchronized boolean check() { return x != y; }
}

Under which condition will check return true when called from a different class?
A. check can never return true.
B. check can return true when setXY is called by multiple threads.
C. check can return true when multiple threads call setX and setY separately.
D. check can return true only if SyncTest is changed to allow x and y to be set
separately.

[Melle Lee]

My answer:

B. True
Since setXY() is not synchronized, the following sequence is possible:
setX(1); // the first thread
setX(2); // the second thread
setY(1); // the first thread
check();
setY(2); // the second thread
[ April 16, 2006: Message edited by: Spring ]

[Shaliey Gowtham]

I too feel Spring is right.

[Amisha Shah]

hi ,

i think A and D are true ans. but i m not sure.

[Amirr Rafique]

Answer would be B.

[Sunil Kumar Gupta]

Originally posted by Amisha Shah:
hi ,

i think A and D are true ans. but i m not sure.

How A and D together can be the right answer, Please read carefully both answers.