JavaWeb运行出错，怎么解决呀

有没有帮忙看看的呀，一直报错这个，代码如下

img

package bean;
public class Student{
    private String sno,sname,sex;
    public Student(){}
    public Student(String sno,String sname,String sex){
        this.sno = sno;
        this.sname = sname;
        this.sex = sex;
    }
    public String getSno(){return sno;}
    public void setSno(String sno){this.sno = sno;}
    public String getSname(){    return sname;}
    public void setSname(String sname){this.sname = sname;}
    public String getSex(){return sex;}
    public void setSex(String sex){this.sex = sex;}
}



package servlet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import bean.Student;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

public class SetStudent extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        List studentlist=new ArrayList<>();//查询结果
        studentlist.add(new Student("001","张三","男"));
        studentlist.add(new Student("002","李四","女"));
        studentlist.add(new Student("003","王五","男"));
        request.setAttribute("result", studentlist);//将查询结果保存到request对象中
        //转发到show.jsp显示查询结果
        request.getRequestDispatcher("show.jsp").forward(request, response);
    }
}


<%@ page  pageEncoding="utf-8" import="java.util.*,bean.Student"%>
<%@ page import="servlet.SetStudent" %>
<%@ taglib  uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
<body>
显示结果(用EL和JSTL)<br/>
<table>
  <tr><th>学号th><th>姓名th><th>性别th>tr>
  <c:forEach var="student" items="${result}">
    <tr><td>${student.sno}td><td>${student.sname}td><td>${student.sex}td>tr>
  c:forEach>
table>
<hr/>查询显示结果(用代码)<br/>
<% List<Student> studentlist=(List<Student>)request.getAttribute("result");%>
  <tr><th>学号th><th>姓名th><th>性别th>tr>
  <%  for(Student student:studentlist){%>
  <tr><td><%=student.getSno()%>td>
    <td><%=student.getSname()%>td>
    <td><%student.getSex();%>td>tr>")
  <%} %>
table>
body>
html>

空指针异常啦，后端传过来的 studentlist 为null