Leetcode-21:Merge Two Sorted Lists

Question:
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.
合并两个有序链表，新列表要求顺序拼接前两个列表来完成。

Answer:

public class Solution {    public ListNode margeTwoLists(ListNode l1, ListNode l2){        if(l1==null)            return l2;        else if(l2==null)            return l1;        else{            return connect(l1,l2);        }    }    public ListNode connect(ListNode l1, ListNode l2){        ListNode res = new ListNode(0);//头结点        ListNode ress = res;        while(l1!=null && l2!=null){            if(l1.val>=l2.val){                res.next = l2;                l2 = l2.next;            }            else if(l1.val<l2.val){                res.next = l1;                l1 = l1.next;            }            res = res.next;        }        if(l1!=null){            res.next = l1;        }        else{            res.next = l2;        }        return ress.next;    }}class ListNode{    int val;    ListNode next;    ListNode(int x){val = x;}}