Exception Handling & Concurrency Flashcards

Which method of ExecutorService blocks until all submitted tasks complete or a timeout occurs?

Answer: awaitTermination(long, TimeUnit)

awaitTermination() blocks the calling thread until the executor terminates or the specified timeout elapses, returning a boolean result.

What kind of exception is java.io.IOException?

Answer: Checked exception

IOException extends Exception (not RuntimeException), making it a checked exception that must be declared or handled.

What does Callable differ from Runnable in terms of return value and exceptions?

Answer: Callable returns a typed value and can throw checked exceptions

Callable defines call() which returns V and declares throws Exception, unlike Runnable's run() which returns void and cannot throw checked exceptions.

Which exception is thrown by BlockingQueue.take() when the current thread is interrupted?

Answer: InterruptedException

BlockingQueue.take() blocks until an element is available and throws InterruptedException if the thread is interrupted while waiting.

In a multi-catch block 'catch (IOException | SQLException e)', what is the type of 'e'?

Answer: A union type that can only be rethrown

In a multi-catch, the variable is implicitly final and typed as the union; it can only be rethrown as-is, not reassigned.

What is a race condition?

Answer: When program output depends on unpredictable relative timing of threads

A race condition occurs when correctness depends on the relative execution order of concurrent threads, which is non-deterministic.

Which atomic class provides a compareAndSet(expected, update) method for lock-free integer updates?

Answer: AtomicInteger

AtomicInteger in java.util.concurrent.atomic provides compareAndSet() (CAS) for lock-free, thread-safe integer manipulation.