Leetcode-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;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode preHead = new ListNode(0);
        ListNode end = preHead;
        while (l1!=null || l2!=null){
            if (l1==null){
                end.next = l2;
                break;
            }

            if (l2==null){
                end.next = l1;
                break;
            }

            if (l1.val<l2.val){
                end.next = l1;
                end = l1;
                l1 = l1.next;
            } else {
                end.next=l2;
                end = l2;
                l2 = l2.next;
            }
        }

        return preHead.next;
    }
}