Reverse a Linked List in groups of given size

Question:

Given a linked list, write a function to reverse every k nodes (where k is an input to the function).

Example:
Inputs:  1->2->3->4->5->6->7->8->NULL and k = 3
Output:  3->2->1->6->5->4->8->7->NULL.

Inputs:   1->2->3->4->5->6->7->80->NULL and k = 5
Output:  5->4->3->2->1->8->7->6->NULL.

Solution:

      /**

        * Reverse every k nodes in a given linked list

        *

        * @param l

        * @param k

        * @return

        */

       public ListNode ReverseBlock(ListNode l, int k)

       {

              if(l==null) {

                     return null;

              }

              else {

                     int count=0;

                     ListNode current, prev, next;

                     current=l;

                     prev=next=null;

                     while(current!=null && count<k){

                           next = current.next;

                           current.next = prev;

                           prev=current;

                           current=next;

                           count++;

                     }

                     // reverse remaining block of nodes

                     if(next!=null) {

                           l.next = ReverseBlock(next, k);

                     }

                     // return new header node

                     return prev;

              }

       }