Bull (15) reverse linked list

 //     Title description
     //     Input a linked list, after reversing the linked list, output all elements of the linked list. 
    public  static  class ListNode {
         int val;
        ListNode next = null;

        ListNode(int val) {
            this.val = val;
        }
    }

    public static ListNode ReverseList(ListNode head) {
        if (head == null) {
            return head;
        }
        ListNode pre = null;
        ListNode now = null;
        while (head != null) {
            ListNode next = head.next;

            now = head;
            now.next = pre;
            pre = now;

            head = next;

        }
//        while (now!=null){
//            System.out.println(now.val);
//            now = now.next;
//        }
        return now;
    }