Core Java اسئلة واجوبة المقابلات

Question: Whats the difference between notify() and notifyAll()?

Answer: notify() is used to unblock one waiting thread; notifyAll() is used to unblock all of them. Using notify() is preferable (for efficiency) when only one blocked thread can benefit from the change (for example, when freeing a buffer back into a pool). notifyAll() is necessary (for correctness) if multiple threads should resume (for example, when releasing a 'writer'?? lock on a file might permit all 'readers'?? to resume).