Mastering Java: The Ultimate Quiz for 'Thinking in Java'

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Dive into the depths of Java with our quiz based on "Thinking in Java, Fourth Edition" by Bruce Eckel. Test your knowledge, solidify concepts, and prepare for certification with challenging questions and insightful feedback.

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

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The DelayQueue holds elements that are instances of which interface?

Runnable
Callable
Future
Delayed

The correct answer is: Delayed

The DelayQueue holds elements that are instances of the Delayed interface, which allows for scheduling an object to be retrieved after a specified delay. Option A, Runnable, is incorrect because it is used to create a thread without any return value. Option B, Callable, is incorrect because it is used to define a task that can return a result, but is not specifically related to a delay. Option C, Future, is incorrect because it represents the result of an asynchronous computation and is not directly related to delays. Therefore, the correct answer is D, as it is the only interface specifically designed for delaying the retrieval of objects from a queue.