如图所示，报错原因是啥？

Question

如图所示，报错原因是啥？Class 'ListNode' is public, should be declared in a file named 'ListNode.java'
我的文件是.java后缀啊

完整代码：

package title.反转链表206;
public class ListNode {
    int val;
    ListNode next;
    ListNode() {};
    ListNode(int val) {this.val = val;};
    ListNode(int val, ListNode next) {this.val = val; this.next = next;};
}
public class test {
    public static void main(String[] args) {
        ListNode ans = new ListNode();
        ListNode head = CreateList();
        ans = new Solution().reverseList(ListNode head);
    }
    static ListNode CreateList() {
        ListNode head = new ListNode();
        for (int i = 0; i < 10; i++) {
            head = new ListNode(i, head);
        }
        return head;
    }
}

//法1：模拟
class Solution {
    public ListNode reverseList(ListNode head) {
        ListNode ans = new ListNode();
        ans.next = null;
        for (ListNode p = head; p != null; p = p.next) {
            ans = new ListNode(p.val, ans);
        }
        return ans;
    }
}

Answer 1

一个java 源码文件中，同级的只能有 一个 public修饰的类，并且这个public 修饰的类 要和 java文件同名