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

What difference does a PriorityQueue introduce in its behavior?

1. Allows random access to elements

2. Keeps elements sorted according to their natural order

3. Sorts elements in FIFO order

4. Positions elements based on their priority

The correct answer is: Positions elements based on their priority

A priority queue follows a particular order, i.e., the "priority" of the elements. The element with the highest priority is placed at the front of the queue, and so on. This is different from a regular queue, which follows the "first in, first out" (FIFO) rule. Option A is incorrect because priority queues do not allow for random access. Option B is incorrect because it does not necessarily keep elements sorted according to their natural order, only according to their priority. Option C is incorrect because, as mentioned, priority queues do not follow the FIFO rule. Therefore, option D is the correct answer as it accurately describes the unique behavior introduced by a priority queue.