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Threads & Synchronization

v iyer
Greenhorn

Joined: Nov 15, 2000
Posts: 3
Which is true is a(), b() & c() can be called at any time
1> i.v is guaranteed always to be 0 or 1
2> j.v is guaranteed always to be 0 or 1
3> k.v is guaranteed always to be 0 or 1
4> j.v will always be >= k.v at any given time
5> k.v will always be >= j.v at any given time
I felt a,b,& c are all true as all methods are synchronized
and hence when the thread is in a() only i is inc & dec
so j & k remain unchanged
similarly b() & c().
But the answer given is only a & b.
Can someone please explain how this works?

class Counter{
int v = 0;
synchronized void inc() {v++;}
synchronized void dec() {v--;}
}
public class test extends Thread{
Counter i;
Counter j;
Counter k;
public synchronized void a(){
i.inc();
System.out.println("a");
i.dec();
}

public synchronized void b(){
i.inc(); j.inc(); k.inc();
System.out.println("b");
i.dec(); j.dec(); k.dec();
}
public synchronized void c(){
k.inc();
System.out.println("c");
k.dec();
}
}
Thanks
V Iyer
 
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subject: Threads & Synchronization