request.getParameterをint型に変更

Javaで新規会員登録を制作しているのですが、Integer.parseIntでint変更時エラーが出ています。
入力画面からPOST送信でフィールド値をセットしたいです。

発生している問題・エラーメッセージ

java.lang.NumberFormatException: null
	java.base/java.lang.Integer.parseInt(Integer.java:614)
	java.base/java.lang.Integer.parseInt(Integer.java:770)
	controller.InsertController.doPost(InsertController.java:26)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

入力画面

<%@ page contentType="text/html; charset=UTF-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>マイページ</title>
		<link href="style.css" rel="stylesheet" type="text/css">
	</head>
	<body>
		<div id="main">
			<h1>入力画面</h1>
			<form action="insert" method="post">
					<label for="email">Email</label>
					<input type="text" id="email=" name="email" value ="${customer.email}">
					<label for="password">Passowrd</label>
					<input type="text" id="password" name="password" value ="${customer.password}">
					<label for="name">氏名</label>
					<input type="text" id="name=" name="name" value="${customer.name}">
					<label for="gender">性別</label>
					<c:if test="${customer.gender == 0}">
						<input type="radio" name="gender" value="0" checked=checked>男
						<input type="radio" name="gender" value="1">女
					</c:if>
					<c:if test="${customer.gender == 1}">
						<input type="radio" name="gender" value="0">男
						<input type="radio" name="gender" value="1" checked=checked>女
					</c:if>
					<label for="blood">血液型</label>
					<select name="blood">
						<option value="${customer.blood}">${customer.blood}型</option>
						<option value="A">A型</option>
						<option value="B">B型</option>
						<option value="O">O型</option>
						<option value="AB">AB型</option>
					</select>
					<label for="name">年齢</label>
					<input type="text" id="nane" name="name" value ="${customer.name}">
					<label for="memo">メモ</label>
					<textarea name="memo" rows="4" cols="41" maxlength="100">${customer.memo}</textarea>
					<input type="submit" value="確認">
			</form>
		</div>
	</body>
</html>

POST送信した値をフィールド値セットするコード

package controller;

import java.io.IOException;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import data.Customer;

@WebServlet("/insert")
public class InsertController extends HttpServlet {
	protected void doPost (HttpServletRequest request, HttpServletResponse response)
			throws ServletException,IOException{
		request.setCharacterEncoding("UTF-8");
		String email = request.getParameter("email");
		String password = request.getParameter("password");
		String name = request.getParameter("name");
		String blood = request.getParameter("blood");
		String gender = request.getParameter("gender");
		int old =Integer.parseInt(request.getParameter("old"));
		String memo= request.getParameter("memo");
		Customer customer = new Customer();
		customer.setEmail(email);
		customer.setPassword(password);
		customer.setName(name);
		customer.setGender(gender);
		customer.setBlood(blood);
		customer.setOld(old);
		customer.setMemo(memo);
		request.setAttribute("customer", customer);
		ServletContext sc = getServletContext();
		sc.getRequestDispatcher("/" + "confirm.jsp").forward(request, response);
	}
}