Reverse The Doubly Linked List

Objective: Reverse The Doubly Linked List.

Example:

Approach:

Every Node in a doubly linked list has next and previous pointer.
Do the linear traversal of the linked list and keep swapping the next and previous pointers.
At the end, make the last pointer as the head of the list.

Complete Code:

	public class reverseDoublyLinkedList {
	public static Node head=null;
	public static Node tail = null;
	public static int size = 0;

	public Node reverseDLL(){
	Node current = head;
	Node temp = null;
	while(current!=null){
	temp = current.prev; //swap the next and prev pointer
	current.prev = current.next;
	current.next = temp;
	current = current.prev;
	}
	return temp.prev;
	}
	public void print(Node head){
	Node current = head;
	while(current!=null){
	System.out.print(" " + current.data);

	current = current.next;
	}
	}

	public void add(int data){
	Node n = new Node(data);
	if(head==null){
	head = n;
	tail = n;
	}else{
	head.prev = n;
	n.next = head;
	head = n;
	}
	size++;
	}
	public static void main(String args[]){
	reverseDoublyLinkedList r = new reverseDoublyLinkedList();
	r.add(1);r.add(2);r.add(3);r.add(4);
	r.print(head);
	Node x = r.reverseDLL();
	System.out.println("");
	r.print(x);
	}
	}

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

Output:

->4->3->2->1
->1->2->3->4