从尾到头打印链表

 1 package com.algorithm;
 2 
 3 import java.util.ArrayList;
 4 import java.util.Collections;
 5 
 6 
 7 public class PrintList {
 8      public ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
 9          ArrayList<Integer> list = new ArrayList<>();
10          
11          if (listNode == null) {
12              return list;
13          }
14          
15          while (listNode != null) {
16             list.add(listNode.val);
17             listNode = listNode.next;
18          }
19          Collections.reverse(list);
20          return list;
21      }
22 }
23 
24 
25 
26 class ListNode {
27     int val ;
28     ListNode next = null ;
29     
30     public ListNode(int val) {
31         this.val = val ;
32     }
33 }