Java 链表反转

package com.example.leetcode;

public class ReverseList {
    public ListNode reverse(ListNode head){
        if (head==null){
            return null;
        }
        ListNode pre=head;
        ListNode current=head.next;
        //最初的时候要指向null
        pre.next=null;
        while (current!=null){
            //先判断下个节点有没有值
            ListNode next =current.next;
            //将当前节点指向前一个节点
            current.next=pre;
            //向后移动
            pre=current;
            //向后移动
            current=next;
        }
        return pre;
    }
}