Circular_queue.java

public class CircularQueue {
    private int[] arr;
    private int front;
    private int rear;
    private int capacity;
    private int size;

    public CircularQueue(int capacity) {
        this.capacity = capacity;
        this.arr = new int[capacity];
        this.front = -1;
        this.rear = -1;
        this.size = 0;
    }

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

    public boolean isFull() {
        return size == capacity;
    }

    public void enqueue(int element) {
        if (isFull()) {
            System.out.println("Queue is full. Cannot enqueue more elements.");
            return;
        }

        if (isEmpty()) {
            front = 0;
        }

        rear = (rear + 1) % capacity;
        arr[rear] = element;
        size++;
    }

    public int dequeue() {
        if (isEmpty()) {
            System.out.println("Queue is empty. Cannot dequeue elements.");
            return -1;
        }

        int element = arr[front];
        if (front == rear) {
            front = -1;
            rear = -1;
        } else {
            front = (front + 1) % capacity;
        }

        size--;

        return element;
    }

    public int front() {
        if (isEmpty()) {
            System.out.println("Queue is empty. No front element.");
            return -1;
        }

        return arr[front];
    }
}
 public static void main(String[] args) {
        CircularQueue queue = new CircularQueue(5);
        queue.enqueue(1);
        queue.enqueue(2);
        queue.enqueue(3);

        System.out.println(queue.dequeue()); // Output: 1
        System.out.println(queue.front());  // Output: 2
    }