Session object problem. help needed

Question

Hi,
I have an application where I am showing records in a chunk of 10 a time and have NEXT/PREVIOUS buttons to iterate.
The user fills in the search criteria and hits the search button that inturn shows the data in a chunk of 10.
I am adding an ArrayList to a session object in a servlet. The first time when user submits the search I create the ArrayList and add to a session object. When I try to access that ArrayList in my jsp page it always gives me null but when I click on a NEXT button the ArrayList is no more null.
Here is the servlet code where I am creating adding ArrayList to a session object:
//The following code is executed everytime the user hits search button or clicks NEXT/PREVIOUS buttons
ArrayList data = getData(val1,val2);
boolean val = false;
Enumeration enum = session.getAttributeNames();
while(enum.hasMoreElements())
  String s = (String)enum.nextElement();
  if(s.equals("arr"))
     val = true;
if(val)
   session.removeAttribute("arr");
//the following returns the correct size everytime even if it's the first time
System.out.println("****************************** ArrayList Size = " + data.size());
session.setAttribute("arr", data);
System.out.println("****************************** ArrayList Size After = " + ((ArrayList)session.getValue("arr")).size());Here is the jsp code where I am calling the servlet:
<img src="http://<%= request.getServerName() %>:<%= request.getServerPort() %><%= request.getContextPath()%>/servlet/DataReq"></a>    
    <%       
        //first time it's returning null which is not right
//I SHOULD NOT GET null I ALWAYS HAVE THE ARRAYLIST. BUT SOMEHOW FIRST-TIME I GET IT null
       ArrayList al = (ArrayList)session.getAttribute("arr");
        if (al != null && (al.size() >0))
            System.out.println("******* DEBUG = " + al.size());
     else
         System.out.println("******* DEBUG NO VALUES ");     
    %>I don't know why the first time ArrayList is null even though I have created and added to a session in a servlet but when clicking NEXT it always returns me the values in it and it's no more null.
Any help is really appreciated.
Thanks!

Answer 1

I keep 10 records a time in an ArrayList but before displaying the data in jsp page I want to call a servlet that gets the data from the DB and stores it in a session object and then I iterate through that session object. The image tag here is for my testing purpose as I am trying to figure out some other way to call a servlet before displaying the data. Here is the code:
//...... Here I want to call a servlet ......
  ArrayList al = (ArrayList)session.getAttribute("arr");
  Iterator iterator = al.iterator();
  while(iterator.hasNext())
    DataRet s = (DataRet)iterator.next());
%>
<tr>
<td align="left" nowrap="nowrap"><%= s.getName()</td>
<td align="left" nowrap="nowrap"><%= s.getID()</td>
<td align="left" nowrap="nowrap"><%= s.getAmount()</td>
<td align="left" nowrap="nowrap"><%= s.getAddr()</td>
<td align="left" nowrap="nowrap"><%= s.getCity()</td>
</tr>
<%
%>
Before getting an ArrayList from a session object I want to call a servlet. How do I call a servlet directly from jsp page.
Any help is really appreciated.
Thanks