Queue.java

package queque.dsa.lab;

import java.util.LinkedList;

public class Queue {
    private LinkedList<Integer> items;

    public Queue() {
        items = new LinkedList<>();
    }

    public boolean isEmpty() {
        return items.isEmpty();
    }

    public void enqueue(int item) {
        items.addLast(item);
    }

    public int dequeue() {
        if (isEmpty()) {
            System.out.println("Queue is empty.");
            return -1;
        }
        return items.removeFirst();
    }

    public int peek() {
        if (isEmpty()) {
            System.out.println("Queue is empty.");
            return -1;
        }
        return items.getFirst();
    }

    public int size() {
        return items.size();
    }

    public static void main(String[] args) {
        Queue queue = new Queue();

        queue.enqueue(10);
        queue.enqueue(20);
        queue.enqueue(30);

        System.out.println("Front element: " + queue.peek());
        System.out.println("Dequeued element: " + queue.dequeue());

        System.out.println("Queue size: " + queue.size());
    }
}