Odd-Even Linked List solution #leetcode328

public ListNode oddEvenList(ListNode head){
    if(head == null || head.next == null) return head;
    ListNode oddHead = new ListNode(-1);
    ListNode evenHead = new ListNode(-1);
    ListNode oddptr = oddHead;
    ListNode evenptr = evenHead;
    ListNode current = head;
    int index = 1;
    while(current!= null){
       if(index%2 == 1){
         oddptr.next = current;
         oddptr = oddptr.next;
        }
        else{
          evenptr.next = current;
          evenptr = evenptr.next;
        }
        current = current.next;
        index++;
     }
     evenptr.next = null;
     oddptr.next = evenHead.next;
     return oddHead.next;
}