// Two constructors are provided: one that creates a queue of default 
// capacity & one that allows the main method to specify the capacity.

public class ArrayBoundedQueue implements BoundedQueueInterface {

	protected final int DEFAULTCAP = 100; // default capacity
	protected Object[] queue; // array that holds queue elements
	protected int numElements = 0; // number of elements in the queue
	protected int front = 0; // index of front of queue
	protected int rear; // index of rear of queue

	public ArrayBoundedQueue() {
		queue = new Object[DEFAULTCAP];
		rear = DEFAULTCAP - 1;
	}

	public ArrayBoundedQueue(int maxSize) {
		queue = new Object[maxSize];
		rear = maxSize - 1;
	}

	@Override
	public void enqueue(Object element) {
		if (isFull())
			System.out.println("Enqueue was attempted on a full queue!");
		else {
			rear = (rear + 1) % queue.length;
			queue[rear] = element;
			numElements = numElements + 1;
		}
	}

	@Override
	public Object dequeue() {
		if (isEmpty()) {
			System.out.println("Dequeue attempted on an empty queue!");
			return null;
		} else {
			Object itemToReturn = queue[front];
			queue[front] = null;
			front = (front + 1) % queue.length;
			numElements = numElements - 1;
			return itemToReturn;
		}
	}

	@Override
	public boolean isEmpty() {
		return (numElements == 0);
	}

	@Override
	public boolean isFull() {
		return (numElements == queue.length);
	}

}