Which statement is true?

Question

Options

• AIllegalStateException is thrown if a thread in waiting state is moved back to runnable.
• BThread in waiting state consumes CPU cycles.
• CA thread in waiting state must handle InterruptedException.
• DAfter the timed wait expires, the waited thread moves to the terminated state.

• A
  6% (3)
• B
  2% (1)
• C
  78% (39)
• D
  14% (7)

Explanation

Option C is correct because methods that place a thread in a waiting state - such as Object.wait(), Thread.sleep(), and Thread.join() - all declare throws InterruptedException. Since this is a checked exception, the Java compiler mandates that calling code either catches it or propagates it, making handling it a syntactic requirement, not just a best practice.

Why the distractors are wrong:

• A - No IllegalStateException is thrown during a waiting-to-runnable transition. That exception is thrown for invalid state in other contexts (e.g., calling start() on an already-started thread).
• B - A waiting thread is deliberately not consuming CPU cycles; the entire purpose of wait() is to release the CPU (and the monitor lock) until notified.
• D - When a timed wait expires, the thread returns to the runnable state, not terminated. Terminated means run() has finished.

Memory tip: InterruptedException is a checked exception - the compiler won't let you ignore it. Anytime you see wait(), sleep(), or join(), think "I must handle InterruptedException" because Java enforces it at compile time.

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