JSP Shopping Cart problem

Question

Hello,
I'm writing a JSP page with a shopping cart so the user can add products to it, nfortunately the thing won't work.. I keep getting an NullPointerException.. I'm probably screwing up somewhere.. I would be very thankful if you could help me out..
this is the code for the Shopping Cart Bean:
[myCart.java]
package myCart;
import java.util.*;
public class myCart implements java.io.Serializable{
     private Vector items;
public String[] getItems(){
     String strTemp[] = new String[items.size()];
     items.copyInto(strTemp);
     return strTemp;
public void setItems(Vector newItems){
     items=newItems;
public void addItem(String newId){
     items.addElement(newId);
This is the JSP page that I'm using:
[myCart.jsp]
<%@ page import="java.sql.*" %>
<%@ page import="java.util.*" %>
<jsp:useBean id="myCart" class="myCart.myCart" scope="session" />
<%
Connection con;
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con = DriverManager.getConnection("jdbc:odbc:produkten");
Statement stmt = con.createStatement();
     ResultSet rs = stmt.executeQuery("SELECT * FROM tblProdukten WHERE NR= "+request.getParameter("nr")+"");
while (rs.next()) {
     String merk = rs.getString("MERK");
     long temp = rs.getLong("NR");
     String nr = Long.toString(temp);
-----> myCart.addItem(nr);
     %>
     <BR>Nr     : <%=nr%>
     <BR>test :     <%=merk%>
     <HR>
<% } %>
<%
     con.close();
     catch(ClassNotFoundException cnfex)
          out.println("jdbc odbc driver not found // muzz");
     catch(SQLException sqlex)     
          out.println(sqlex);
%>
</TABLE>
</BODY>
</HTML>
I think I probably(??) put the <myCart.addItem> in the wrong part of the code..??
Greetings,
Michael

Answer 1

yes, I see, I forgot to initiate that, I'm still
learning so please bare with me :)
I now initiated the <items> vector like this:
Vector items = new Vector();
and added this:
myCart.items.addItem(nr);
But it still won't work correctly >>
First error: Your Vector items is not a public variable. Therefore, outside classes will not be able to access it. No problem though, you have a method to take care of that. Instead of what you're doing, simply call
myCart.addItem(nr)This calls the public method addItem(String) which accesses your private Vector items, and adds a string to the vector.
Your second error should be taken care of. It is resulting from the fact that instead of calling the method addItem() from teh class instance, youre trying to access the Vector items first, and then trying to call addItem() from that... not only can you not access that variable, as stated above, but there is no method in Vector called addItems(). You could conceivably make items public, but I'd stick with what you've got.