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Thread Question

Daniel
Greenhorn

Joined: Dec 01, 2000
Posts: 9
Given the following code, which statements concerning the objects referenced through the member variables i, j and k are true, given that any thread may call the methods a, b and c at any time?
class Counter {
int v = 0;
synchronized void inc() { v++; }
synchronized void dec() { v--; }
}
public class Q7ed5 {
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 void c() {
k.inc();
System.out.println("c");
k.dec();
}
}
Select all valid answers
1. i.v is guaranteed always to be or 1.
2. j.v is guaranteed always to be or 1.
3. k.v is guaranteed always to be or 1.
4. j.v will always be greater than or equal to k.v at any given time.
5. k.v will always be greater than or equal to j.v at any given time.
Ajith Kallambella
Sheriff

Joined: Mar 17, 2000
Posts: 5782
Actually none of the answers are right. I started writing my explanation, but soon found out this exact topic has been discussed here before -
http://www.javaranch.com/ubb/Forum24/HTML/000446.html
Ajith


Open Group Certified Distinguished IT Architect. Open Group Certified Master IT Architect. Sun Certified Architect (SCEA).
 
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subject: Thread Question