public class Queue {

private Node front;

private Node back;

public void enqueue(int value) {

Node newNode = new Node(value);

if (front == null) {

front = newNode;

back = newNode;

} else {

back.next = newNode;

back = newNode;

}

System.out.println("Enqueued " + value);

}

public int dequeue() {

int value = front.value;

front = front.next;

System.out.println("Dequeued " + value);

return value;

}

public int peek() {

return front.value;

}

public boolean isEmpty() {

return front == null;

}

public String toString() {

return "FRONT -> " + ((front == null) ? "[EMPTY]" : front.toString()) + " -> BACK";

}

public static void main(String[] args) {

// example usage

Queue queue = new Queue();

queue.enqueue(1);

queue.enqueue(2);

queue.enqueue(3);

queue.enqueue(4);

System.out.println(queue);

queue.dequeue();

queue.dequeue();

System.out.println(queue);

queue.enqueue(5);

queue.enqueue(6);

queue.enqueue(7);

System.out.println(queue);

queue.dequeue();

queue.dequeue();

queue.dequeue();

queue.dequeue();

queue.dequeue();

System.out.println(queue);

}

}