Doubly Linked List Programs

class Node {
    int data;
    Node next;
    Node prev;

    public Node(int data) {
        this.data = data;
        this.next = null;
        this.prev = null;
    }
}

class DoublyLinkedList {
    private Node head;
    private Node tail;

    public void append(int data) {
        Node newNode = new Node(data);
        if (head == null) {
            head = newNode;
            tail = newNode;
        } else {
            newNode.prev = tail;
            tail.next = newNode;
            tail = newNode;
        }
    }

    public void prepend(int data) {
        Node newNode = new Node(data);
        if (head == null) {
            head = newNode;
            tail = newNode;
        } else {
            newNode.next = head;
            head.prev = newNode;
            head = newNode;
        }
    }

    public void delete(int data) {
        Node current = head;
        while (current != null) {
            if (current.data == data) {
                if (current.prev != null) {
                    current.prev.next = current.next;
                } else {
                    head = current.next;
                }
                if (current.next != null) {
                    current.next.prev = current.prev;
                } else {
                    tail = current.prev;
                }
                return;
            }
            current = current.next;
        }
    }

    public void displayForward() {
        Node current = head;
        while (current != null) {
            System.out.print(current.data + " <-> ");
            current = current.next;
        }
        System.out.println("null");
    }

    public void displayBackward() {
        Node current = tail;
        while (current != null) {
            System.out.print(current.data + " <-> ");
            current = current.prev;
        }
        System.out.println("null");
    }
}

public class DoublyLinkedListExample {
    public static void main(String[] args) {
        DoublyLinkedList dll = new DoublyLinkedList();
        dll.append(1);
        dll.append(2);
        dll.append(3);

        System.out.println("Doubly Linked List (Forward):");
        dll.displayForward();

        System.out.println("Doubly Linked List (Backward):");
        dll.displayBackward();

        dll.delete(2);
        System.out.println("Doubly Linked List after deleting 2 (Forward):");
        dll.displayForward();
    }
}