Reverse Linked List

 1 public class Solution {
 2     public static ListNode reverseList(ListNode head) {
 3        if(head==null) return null;
 4        ListNode newHead=new ListNode(0);
 5        ListNode prehead=head.next;
 6        while(true){
 7        head.next=newHead.next;
 8        newHead.next=head;
 9        if(prehead==null) break;
10        head=prehead;
11        prehead=head.next;
12        }
13        return newHead.next;
14     }
15     public static class ListNode {
16     int val;
17     ListNode next;
18     ListNode(int x) {
19         val = x;
20     }
21     }
22     public static void main(String[]args){
23     ListNode[]node=new ListNode[4];
24     for(int i=0;i<node.length;i++){
25         node[i]=new ListNode(i);
26     }
27     node[0].next=node[1];
28     node[1].next=node[2];
29     node[2].next=node[3];
30     ListNode head=reverseList(node[0]);
31     while(head!=null){
32         System.out.println(head.val);
33         head=head.next;
34     }
35     }
36 }