Newbie - JSP & bean shopping cart logic error?

Question

Hello,
I am attempting to bulid a shopping cart facility on a JSP site that I am building.
I am having difficulties adding an item to the basket.
The page below (bookDetail.jsp) displays items for sale from a database. At the foot of the page, I have set up a hyperlink to add an item to a basket bean instance created in this page.
What happens is the page will load correctly, when i hover the mouse over the hyperlink to add the item to the basket, the status bar shows the URL of the current page with the details of the book appended. This is what I want. But when I click the link, the page will only reload showing 20% of the content.
Netbeans throws up no errors, neither does Tomcat, so I am assuming I have made a logical error somewhere.
I have enclosed the Book class, and the ShoppingCart class for your reference.
Any help would be really appreciated as I am at a loss here.
Cheers.
Edited highlights from bookDetail.jsp
//page header importing 2 classes - Book and ShoppingCart
<%@ page import="java.util.*, java.sql.*, com.shopengine.Book, com.shopengine.ShoppingCart" errorPage="errorpage.jsp" %>
//declare variables to store data retrieved from database
String rs_BookDetail_bookRef = null;
String rs_BookDetail_bookTitle = null;
String rs_BookDetail_author = null;
String rs_BookDetail_price = null;
//code that retrieves recordset data, displays it, and places it in variables shown above
<%=(((rs_BookDetail_bookRef = rs_BookDetail.getString("book_ref"))==null || rs_BookDetail.wasNull())?"":rs_BookDetail_bookRef)%>
<%=(((rs_BookDetail_author = rs_BookDetail.getString("author"))==null || rs_BookDetail.wasNull())?"":rs_BookDetail_author)%>
<%=(((rs_BookDetail_bookTitle = rs_BookDetail.getString("book_title"))==null || rs_BookDetail.wasNull())?"":rs_BookDetail_bookTitle)%>
<%=(((rs_BookDetail_price = rs_BookDetail.getString("price"))==null || rs_BookDetail.wasNull())?"":rs_BookDetail_price)%>
//this link is to THIS PAGE to send data to server as request parameters in Key/Value pairs
// this facilitates the add to basket function
<a href="<%= response.encodeURL(bookDetail.jsp?title=
"+rs_BookDetail_bookTitle+"
&item_id=
"+rs_BookDetail_bookRef +"
&author="+rs_BookDetail_author +"
&price=
"+rs_BookDetail_price) %> ">
<img src="images\addtobasket.gif" border="0" alt="Add To Basket"></a></td>
// use a bean instance to store basket items
<jsp:useBean id="basket" class="ShoppingCart" scope="session"/>
<% String title = request.getParameter("title");
if(title!=null)
String item_id = request.getParameter("item_id");
double price = Double.parseDouble(request.getParameter("price"));
Book item = new Book(item_id, title, author, price);
basket.addToBasket( item );
%>
ShoppingCart class that is used as a bean in bookDetail.jsp shown above
package com.shopengine;
//import packages
import java.util.*;
//does not declare explicit constructor which automatically creates a zero argument constructor
//as this class will be instantiated as a bean
public class ShoppingCart
//using private instance variables as per JavaBean api
     private Vector basket;
     public ShoppingCart()
          basket = new Vector();
     }//close constructor
//add object to vector
     public void addToBasket (Book book)
          basket.addElement(book);
     }//close addToBasket method
//if strings are equal, delete object from vector
     public void deleteFromBasket (String foo)
for(Enumeration enum = getBasketContents();
enum.hasMoreElements();)
//enumerate elements in vector
Book item = (Book)enum.nextElement();
//if BookRef is equal to Ref of item for deletion
//then delete object from vector.
if (item.getBookRef().equals(foo))
basket.removeElement(item);
break;
}//close if statement
}//close for loop
     }//close deleteFromBasket method
//overwrite vector with new empty vector for next customer
     public void emptyBasket()
basket = new Vector();
     }//close emptyBasket method
     //return size of vector to show how many items it contains
public int getSizeOfBasket()
return basket.size();
     }//close getSizeOfBasket method
//return objects stored in Vector
     public Enumeration getBasketContents()
return basket.elements();
     }//close getBasketContents method
     public double getTotalPrice()
//collect book objects using getBasketContents method
Enumeration enum = getBasketContents();
//instantiate variable to accrue billng total for each enummeration
double totalBillAmount;
//instantiate object to store data for each enummeration
Book item;
//create a loop to add up the total cost of items in basket
for (totalBillAmount=0.0D; enum.hasMoreElements(); totalBillAmount += item.getPrice())
item = (Book)enum.nextElement();
}//close for loop
return totalBillAmount;
     }//close getTotalPrice method
}//close shopping cart class
Book Class that is used as an object model for items stored in basket
package com.shopengine;
import java.util.*;
public class Book{
     //define variables
private String bookRef, bookTitle, author;
     private double price;
//define class
public Book(String bookRef, String bookTitle, String author, double price)
this.bookRef= bookRef;
this.bookTitle=bookTitle;
this.author=author;
this.price=price;
//create accessor methods
     public String getBookRef()
          return this.bookRef;
     public String getBookTitle()
          return this.bookTitle;
     public String getAuthor()
          return this.author;
     public double getPrice()
          return this.price;
}//close class

Answer 1

page will only reload showing 20% of the content.Im building some carts too and I had a similiar problem getting null values from the mysql database. Are you getting null values or are they just not showing up or what?
On one of the carts I'm building I have a similiar class to yours called products that I cast onto a hashmap works alot better. Mine looks like this, maybe this is no help I don't know.......
public class Product {
    /**An Item that is for sale.*/
      private String productID = "Missing";
      private String categoryID = "Missing";
      private String modelNumber = "Missing";
      private String modelName = "Missing";
      private String productImage = "Missing";
      private double unitCost;
      private String description = "Missing";
      public Product( 
                       String productID,
                       String categoryID,
                       String modelNumber,
                       String modelName,
                       String productImage,
                       double unitCost,
                       String description) {
                       setProductID(productID);
                       setCategoryID(categoryID);
                       setModelNumber(modelNumber);
                       setModelName(modelName);
                       setProductImage(productImage);
                       setUnitCost(unitCost);
                       setDescription(description);        
      public String getProductID(){
         return(productID);
      private void setProductID(String productID){
         this.productID = productID;
      public String getCategoryID(){
         return(categoryID);
      private void setCategoryID(String categoryID){
         this.categoryID = categoryID;
      public String getModelNumber(){
         return(modelNumber);
      private void setModelNumber(String modelNumber){
         this.modelNumber = modelNumber;
      public String getModelName(){
         return(modelName);
      private void setModelName(String modelName){
         this.modelName = modelName;
      public String getProductImage(){
         return(productImage);
      private void setProductImage(String productImage){
         this.productImage = productImage;
      public double getUnitCost(){
          return(unitCost);
      private void setUnitCost(double unitCost){
          this.unitCost = unitCost;
      public String getDescription(){
          return(description);
      private void setDescription(String description){
          this.description = description;