Exam 1z0-819 topic 1 question 81 discussion

There is no right answer here. Variables that form the object's state are int a = 0; int b = 0; int c = 0; The problem is with policy for managing concurrent access to the object's state. Concurrent access to it can be done within the package directly. Reads and writes are atomic for reference variables and for most primitive variables (all types except long and double). So, there is the guarantee that it is atomic, but with no guarantees about the visibility of the (potentially) new value from other threads.

answer: B public class A int a = 0; int b = 0; int c = 0; First of all, class A is thread-safe because declaring variables a,b,c is not private. It is possible to change the value of them within the package directly. C. Failed Reads and writes are atomic for reference variables and for most primitive variables (all types except long and double). Method setB does not establish a happens-before relationship, so it’s simply that there is no guarantee that the modification it causes is visible in other threads. All you get in this case is the guarantee that the it is atomic, but with no guarantees about the visibility of the (potentially) new value. So, that means that both methods should be synchronized

B is correct!

Obviously B.

The correct answer is B. Make foo and setB synchronized. Class A is not thread-safe because the methods foo and setB can be called concurrently by multiple threads, leading to race conditions when accessing and modifying the shared variables a, b, and c. To make class A thread-safe, both methods foo and setB should be made synchronized. This ensures that only one thread can execute either method at a time, preventing race conditions.

Answer: B