Merge Two Sorted Lists

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

Solution:

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode rts = new ListNode(0);
        ListNode r = rts;
        while(l1 != null || l2 != null){
            if(l1 == null){rts.next = l2; return r.next;}
            if(l2 == null){rts.next = l1; return r.next;}
            if(l1.val < l2.val) {rts.next = l1; l1 = l1.next;}
            else {rts.next = l2; l2 = l2.next;}
            rts = rts.next;
        }
        return r.next;
    }
}