Servlet-JSP population

In refernce to this Question
http://www.roseindia.net/answers/viewanswers/9843.html

I reduced my servlet code and JSP code as shown below. I have one problem. If I check all the items i'm displaying in my jsp page my code is working fine. If I dont check any of the item in my table in jsp page, it is throwing me an error.

Please let me know how to change my code.

ServletCode:
------------------------------------
package com.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
* Servlet implementation class updateCart
*/
public class updateCart extends HttpServlet {

private static final long serialVersionUID = 1L;

/**
* @see HttpServlet#HttpServlet()
*/
public updateCart() {
super();
// TODO Auto-generated constructor stub
}

/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}

/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
HttpSession session = request.getSession();

String paynow =null;
paynow = request.getParameter("direction").toString();
if(paynow.equals("PayNow")){

RequestDispatcher rd;
rd = request.getRequestDispatcher("/thankyou.jsp");
rd.forward(request,response);

}

String edit_to_cart = null;
edit_to_cart = request.getParameter("direction").toString();

String add_to_cart = null;
String checkout = null;
ArrayList <Integer> total = new ArrayList <Integer>();

add_to_cart=request.getParameter("direction").toString();

checkout = request.getParameter("direction").toString();

//PrintWriter pw = response.getWriter();
//pw.println(add_to_cart);

if (add_to_cart.equals("Add2Cart")||edit_to_cart.equals("EditCart")){
String[] checkValues=request.getParameterValues("box");
int i=0;

for(String Value:checkValues){
int chair_num;

String number =request.getParameter("number");
chair_num = Integer.parseInt(number);
String price = request.getParameter("price");
int price_num = Integer.parseInt(price);
total.add((chair_num*price_num));
i++;

session.setAttribute("c1", chair_num);
}

RequestDispatcher rd;
rd = request.getRequestDispatcher("/cartupdate.jsp");
rd.forward(request,response);

}

if (checkout.equals("checkout1")){

session.setAttribute("efg",total);

RequestDispatcher rd;
rd = request.getRequestDispatcher("/checkout.jsp");
rd.forward(request,response);

}
}
}

JSP CODE:
-------------------------------------
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><%@page
language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<html>
<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%@page import ="java.util.ArrayList" %>
<head>
<title>cartupdate</title>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
</head>
<body>
<%@ include file="header.jsp"%>
<%@ include file="left.jsp"%>

<style>
div.form {
float: center;
width: 30%;
height:50%;
margin-right: auto;
}

</style>
<form method="post" action="updateCart">

<%
Class.forName("oracle.jdbc.driver.OracleDriver");

String serverName = "127.0.0.1";
String portNumber = "1521";
String sid = "orcl";
String url = "jdbc:oracle:thin:@" + serverName + ":" + portNumber + ":" + sid;
String username = "scott"; String password = "tiger";
Connection connection = DriverManager.getConnection(url, username, password);

Statement statement = connection.createStatement() ;
ResultSet rs;
rs = statement.executeQuery("select * from cartlist");
int i=1;
out.println("connection made");%>
<TABLE cellpadding="5" border="1">
<tr>
<td>&nbsp</td>
<td>Item</td>
<td>Price</td>
<td>Units</td>
</tr><%

while (rs.next()){

%>
<tr><td><input type="checkbox" name="box" value= "<%=i%>"/></td>
<td><input type="text" name= "name" value="<%=rs.getString(1)%>" readonly/></td>
<td><input type="text" name="price" value="<%=rs.getString(2)%>" readonly/></td>
<td><input type="text" name="number" /></td>
</tr>
<%i++;}%>

</table>
<p><input type="submit" name="direction" value="Add2Cart">
<input type="submit" name="direction" value="checkout1"><b>Click checkout once you Add2Cart</b> </p>
<p><br></p>
<p></p>
</form>

</body>

</html>

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