public class LinkedListRevert {

    public static void main(String[] args) {

        Node next3 = new Node(4,null);

        Node next2 = new Node(3,next3);

        Node next = new Node(2,next2);

        Node head =new Node(1,next);

        Node tmp = head; // 保存首节点

        while (head!=null){

            System.out.println(head.value);

            head=head.next;

        }

        Node revertHead = revert(tmp);

        while (revertHead!=null){

            System.out.println(revertHead.value);

            revertHead=revertHead.next;

        }

    }

    public static Node revert(Node head){

        Node prev = null;

        Node next = head.next;

        while(head!=null){

            next = head.next;

            head.next = prev;

            prev = head;

            head = next;

        }

        return prev;

    }

}

class Node{

    int value;

    Node next;

    public Node (int value,Node next){

        this.value = value;

        this.next = next;

    }

}