Passing database results from servlets to jsp

Question

Hi everyone,
I have been trying to do what i thought would be a very simple thing...perform a search based on some criteria, and return the query result back to be displayed on a jsp page.
I have a jsp page where some dropdown lists are populated on entry to the page. This works fine. I want to (eventually!) perform the search based on what is selected in these dropdowns. When i click the search button, i invoke a servlet called "SearchInventory.java" which gets the result. I then store this result in an ArrayList object. I then set a bean property (bean name->SearchBean, property->inventory) from within the servlet, and redirect back to the search page. This works if the query only gets back one column.
Unfortunately, when i ask for more than one column in the query, i get a "java.lang.NullPointerException" error.
Here is my code for all segments:
JSP:
<%@ page language="java" import="java.util.ArrayList,java.lang.*,java.sql.*,javax.sql.*,PopLists.PopInvLists,beans.SearchBean"%>
<%
SearchBean sbean=new SearchBean();
ArrayList myAry=sbean.getInventory();
int size=myAry.size();
%>
<%
          for(int i=0;i<size;i++){
               String pname=(String)myAry.get(i);
     %>               
<%}%>
Servlet:
String QueryStr="select ProdName,ManufName from products";// where ProdID="+ProdID;
Statement stmt=conn.createStatement();
rs=stmt.executeQuery(QueryStr);
while(rs.next()){
     rowAry.add(rs.getString(1));
     rowAry.add(rs.getString(2));
     rowSetAry.add(rowAry.clone());
sbean.setInventory(rowSetAry);
req.getSession(true).setAttribute("s_resbean",sbean);
res.sendRedirect("/DBTest/SearchInventory.jsp");
In the servlet, i have also tried the following method of redirecting back to jsp page:
String url="/SearchInventory.jsp";
RequestDispatcher dispatcher=getServletContext().getRequestDispatcher(url);
dispatcher.forward(req,res);
...this gives me a java.lang.ClassCastException
here is my "bean" class:
public class SearchBean extends HttpServlet{
     private int searchFlag=0;
     private static ArrayList inventory;
     public static ArrayList getInventory(){
          return inventory;
     public void setInventory(ArrayList rs){
          this.inventory=rs;
When i perform a query that selects just one column, and doesn't use any sort of search fields for selecting, it does seem to work. for eg, : "select ProdName from products" as the query will return the product names successfully.
Now, i realize what i'm doing is not correct....however, i don't know what the correct way of doing this is. Can someone please please show me how i should be going about doing all of this? It really shouldn't be difficult, but I just can't seem to get it to work.
Thanks in advance,
Aditya

Answer 1

U have instantiated a search bean and populated its member variable i.e Array list , and added that bean to the session as an attribute. Then again why u need to instantiate the search bean in the jsp page.
What has to be done.
In the jsp page instead of instantiating the search bean ,get the search bean from the session attribute.
statement to be removed : SearchBean bean=new SearchBean()
statement to be added : SearchBean bean = session.getAttribute("bean");