Addtwonumbers

/**
 * 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) {
        long number1 = Long.parseLong(getNumber(l1, ""));
        long number2 = Long.parseLong(getNumber(l2, ""));
        long sum = number1 + number2;

        ListNode result = fromString(String.valueOf(sum));
        return result;
    }
    
    ListNode fromString(String num) {
        int size = num.length();
        ListNode head = new ListNode(Character.getNumericValue(num.charAt((size - 1))));
        ListNode current = head;
        for (int i = size - 2; i >= 0; i--) {
            current.next = new ListNode(Character.getNumericValue(num.charAt(i)));
            current = current.next;
        }
        return head;
    }

     String getNumber(ListNode head, String num) {
        if (head == null) {
            return new StringBuilder(num).reverse().toString();
        } else {
            num += "" + head.val;
            return getNumber(head.next, num);
        }
    }
}