Question

Write a class CircularArrayQueue such that all the following methods are implemented:

1. enqueue

2. dequeue

3. first

4. isEmpty

5. size

6. toString

Answer 1

public class CircularArrayQueue {

    private static final int capacity = 100;
    private int front, rear, size;
    private Object[] data;

    public CircularArrayQueue() {
        front = rear = size = 0;
        data = new Object[capacity];
    }

    public CircularArrayQueue(int init) {
        front = rear = size = 0;
        data = new Object[init];
    }

    public void enqueue(Object element) {
        data[rear] = element;
        rear = (rear + 1) % data.length;
        size++;
    }


    public Object dequeue() {
        Object value = data[front];
        data[front] = null;
        front = (front + 1) % data.length;
        size--;
        return value;
    }


    public Object first() {
        return data[front];
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public int size() {
        return size;
    }

    public String toString() {
        String value = "";
        int s = 0;
        while (s < size) {
            if (data[s] != null) {
                value += data[s].toString() + "\n";
            }
            s++;
        }
        return value;
    }
}