1Z0-811 Question #7: Real Exam Question with Answer & Explanation

The correct answer is D. do-while. Option D (do-while) is correct because a do-while loop executes its body at least once before checking the condition. When traversing an array in reverse, you initialize an index at arr.length - 1. For an empty array, this is -1, and the loop will still execute once, attempting a

Control Flow

Question

You have been asked to develop a Java program that prints the elements of an array in reverse order.
Which looping statement cannot be used to meet the requirement?

Options

Aenhanced for
Bstandard for
Cwhile
Ddo-while

Explanation

Option D (do-while) is correct because a do-while loop executes its body at least once before checking the condition. When traversing an array in reverse, you initialize an index at arr.length - 1. For an empty array, this is -1, and the loop will still execute once, attempting arr[-1] and throwing an ArrayIndexOutOfBoundsException - making it fundamentally unreliable for this task.

Why the distractors are wrong:

A (enhanced for) - while it iterates forward, it can be used indirectly (e.g., pushing elements onto a stack then printing), so it is not disqualified outright.
B (standard for) - easily handles reverse iteration: for (int i = arr.length - 1; i >= 0; i--).
C (while) - also works: initialize outside, check condition before entering, decrement inside - it safely handles empty arrays by never entering the loop.

Memory tip: Think "Do-while = Does it No Matter What." Any loop that forces at least one execution is dangerous when zero iterations may be needed - and an empty array in reverse needs exactly zero iterations.

Topics

#Loop Constructs#Array Iteration#Edge Cases#Control Flow

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