今天在写实验报告，遇到一个问题在开启服务器时报404手动输入地址后报500仔细看一下500页面的报错信息，发现了这个提示java.lang.IllegalStateException: Optional int parameter 'cno' is present but cannot be translated into a null value due to being declared as

import java.util.*;public class Main {public static void main(String[] args) {// TODO Auto-generated method stubScanner reader = new Scanner(System.in);int a = reader.nextInt();int b = reader.nextInt(