Java Programming - MCQ Practice Questions

What will happen if you try to call start() on a thread that has already completed execution?

Consider the code: synchronized void method1() { wait(); } If wait() is called without a lock, what happens?

What is the purpose of the yield() method in Java threading?

Which Java class provides thread-safe operations using Compare-And-Swap (CAS)?

What does the volatile keyword guarantee in multithreading?

In Java 21, which new feature was introduced for concurrent programming?

What is the output of this code snippet? ExecutorService es = Executors.newFixedThreadPool(2); es.execute(() -> System.out.println("Task 1")); es.shutdown();

What exception does CyclicBarrier throw when a thread is interrupted while waiting?

In a producer-consumer scenario using BlockingQueue, what happens when a consumer thread calls take() on an empty queue?

A multi-threaded application experiences poor performance despite having adequate CPU cores. Code inspection reveals frequent calls to synchronized blocks on shared objects. Which modern Java feature (2024-25) could optimize this without major refactoring?