queue_array_list

import java.util.ArrayList;

class GenericQueue<T> {
    private ArrayList<T> queue;

    // Constructor
    public GenericQueue() {
        queue = new ArrayList<>();
    }

    // Enqueue method to add an element to the end of the queue
    public void enqueue(T value) {
        queue.add(value);
    }

    // Dequeue method to remove and return the front element of the queue
    public T dequeue() {
        if (isEmpty()) {
            throw new IllegalStateException("Queue is empty");
        }
        return queue.remove(0);
    }

    // Peek method to return the front element without removing it
    public T peek() {
        if (isEmpty()) {
            throw new IllegalStateException("Queue is empty");
        }
        return queue.get(0);
    }

    // Check if the queue is empty
    public boolean isEmpty() {
        return queue.isEmpty();
    }

    // Get the size of the queue
    public int size() {
        return queue.size();
    }
}

public class GenericQueueDemo {
    public static void main(String[] args) {
        // Integer queue
        GenericQueue<Integer> intQueue = new GenericQueue<>();
        intQueue.enqueue(1);
        intQueue.enqueue(2);
        intQueue.enqueue(3);
        System.out.println("Front of Integer queue: " + intQueue.peek());
        System.out.println("Dequeue from Integer queue: " + intQueue.dequeue());
        System.out.println("Size of Integer queue: " + intQueue.size());

        // Double queue
        GenericQueue<Double> doubleQueue = new GenericQueue<>();
        doubleQueue.enqueue(1.1);
        doubleQueue.enqueue(2.2);
        doubleQueue.enqueue(3.3);
        System.out.println("Front of Double queue: " + doubleQueue.peek());
        System.out.println("Dequeue from Double queue: " + doubleQueue.dequeue());
        System.out.println("Size of Double queue: " + doubleQueue.size());

        // String queue
        GenericQueue<String> stringQueue = new GenericQueue<>();
        stringQueue.enqueue("Hello");
        stringQueue.enqueue("World");
        System.out.println("Front of String queue: " + stringQueue.peek());
        System.out.println("Dequeue from String queue: " + stringQueue.dequeue());
        System.out.println("Size of String queue: " + stringQueue.size());
    }
}