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.

/**
 * 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) {
        
            if (l1==null || l2==null) {
                if (l1 != null) {
                    return l1;
                }
                if (l2 != null) {
                    return l2;
                }
                return null;
            }
            ListNode first;
            ListNode curr;
            if (l1.val < l2.val) {
                curr=l1;
                l1=l1.next;
            }else {
                curr=l2;
                l2=l2.next;
            }
            first=curr;
            while (l1!=null && l2!=null) {
                if (l1.val<l2.val) {
                    curr.next=l1;
                    l1=l1.next;
                    curr=curr.next;
                }else {
                    curr.next=l2;
                    l2=l2.next;
                    curr=curr.next;
                }
            }
            if (l1!=null) {
                curr.next=l1;
            }
            if (l2!=null) {
                curr.next=l2;
            }
            return first;
    }
}