Add Two Numbers

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        ListNode t1 = l1, t2 = l2, start = null, current = null;
        int carry = 0;
        while(t1 != null || t2 != null || carry != 0)
        {
            int num1 = t1 == null ? 0 : t1.val;
            int num2 = t2 == null ? 0 : t2.val;
            int temp = (num1+num2+carry)%10;
            carry = (num1+num2+carry)/10;
            if(start == null)
            {
                start = new ListNode(temp);
                current = start;
            }//end if
            else{
                current.next = new ListNode(temp);
                current = current.next;
            }//end else
            t1 = t1 == null ? null : t1.next;
            t2 = t2 == null ? null : t2.next;
        }//end while
        return start;
    }
}