Switching Between Stack and Queue with ArrayDeque

In this problem, you will create methods that receive a comma-separated string of elements and use ArrayDeque to reorder them in either stack (LIFO) or queue (FIFO) order.

Learning Objective: Understand how to use Deque as both a stack (LIFO) and a queue (FIFO)

Overview

Create methods using ArrayDeque to demonstrate the difference between stack and queue operations on the same data.

Specifications

stackOrder(String elements) method

• Receives a comma-separated element string (e.g., "A,B,C")
• Adds each element using push() and retrieves all using pop()
• Returns elements joined by newlines (LIFO order)

queueOrder(String elements) method

• Receives a comma-separated element string (e.g., "A,B,C")
• Adds each element using add() and retrieves all using poll()
• Returns elements joined by newlines (FIFO order)

Example

stackOrder("A,B,C") → "C\nB\nA"
queueOrder("A,B,C") → "A\nB\nC"