Exam 1z0-819 topic 1 question 38 discussion

answer: CD Thread safety is the avoidance of data races When the result of multiple threads executing a critical section may differ depending on the sequence in which the threads execute The reason of that could be visibility and atomicity problem. Note that atomicity is very different to visibility. After atomic operation we can see another value without the happens-before relationship (see Java Memory Model). To avoid data inconsistency we can use synchronized statements or atomic operator like AtomicInteger. B Failed the use of volatile variables are limited, in non atomic operations (auto increment) E. Failed by definition synchronized statement synchronized(sync_object) {}

D => 0nly one observarion, Notice atomic.incrementAndGet is ++testcont atomicinteget.getAndIncrement is testcount ++

Option C replaces line 3 with a synchronized block that synchronizes on the test object. This ensures that only one thread can execute the code within the synchronized block at a time, preventing race conditions when multiple threads try to increment the count variable simultaneously. Option D replaces line 1 with an AtomicInteger variable, which provides atomic operations for updating its value. The incrementAndGet method is then used on line 3 to atomically increment the value of the count variable. This also prevents race conditions when multiple threads try to increment the count variable simultaneously.

D & C is correct And E is not because synchronized can only be used with objects or references to objects and used to lock objects.

E is syntactically wrong