Reverse doubly linked list
If we are allowed to pass the tail node to the reversal method (Node reverseDLL(Node head, Node tail)), we can perform the reversal by reversing the data integer fields instead of restructuring the list. All in all, I had this in mind:

import java.util.ArrayList;
import java.util.List;

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

    Node(int data) {
        this.data = data;
    }
}

public class ReverseDLL {

    static void reverseDLL2(Node head, Node tail) {
        Node left = head; 
        Node right = tail;

        while (true) {
            if (left == right) {
                return;
            }

            int tmp = left.data;
            left.data = right.data;
            right.data = tmp;

            if (left.next == right) {
                return;
            }

            left = left.next;
            right = right.prev;
        }
    }

    static void printList(Node head) {
        for (Node current = head; current != null; current = current.next) {
            System.out.print(current.data);
            System.out.print(" ");
        }
    }

    public static void main(String[] args) {
        List&lt;Node&gt; nodes = new ArrayList&lt;&gt;();

        for (int i = 0; i &lt; 10; ++i) {
            nodes.add(new Node(i));
        }

        for (int i = 0; i &lt; 9; ++i) {
            nodes.get(i).next = nodes.get(i + 1);
        }

        for (int i = 1; i &lt; 10; ++i) {
            nodes.get(i).prev = nodes.get(i - 1);
        }

        printList(nodes.get(0));
        reverseDLL2(nodes.get(0), nodes.get(9));
        System.out.println();
        printList(nodes.get(0));
        reverseDLL2(null, null);
    }
}


Hope that helps.