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Null Pointer Exception in JSP

843840Oct 23 2008 — edited Oct 25 2008
Hi there. I'm fairly new to Java and I hope this is the correct place to post this. :)

I'm trying to build a partial Bulletin Board using a servlet, two java beans, and JSP. One of the JSP pages lists all messages from an associated MS Access database.

Am constantly getting a Null Pointer Exception when I try to view this page.

Please help! I have no idea where I'm going wrong, so all advice is appreciated.

I've posted the section of the servlet this pertains to, as well as the JSP, below.
//-------------------------------------------------------- 
  public void viewMessageList(HttpServletRequest request,
                      HttpServletResponse response )
                      throws IOException, ServletException
  {
    // Set up SQL...
    String query = "SELECT * from message";
    
    ResultSet rs = JDBCQuery( query );
    if( rs == null )
    {
      showError( request, response, errorMessage );
      return;
    }

    // Copy all records into objects and stick
    // the objects into a Collection...
    
    List messageList = null;
    messageList = new ArrayList();
    try
    {
      while( rs.next() )
      {
        MessageBean bean = new MessageBean();
        bean.setMessageID( rs.getString( "messageID" ) );
        bean.setUserID( rs.getString( "userID" ) );
        bean.setSubject( rs.getString( "subject" ) );
        bean.setMessage( rs.getString( "message" ) );
        bean.setDateposted( rs.getString( "dateposted" ) );
        messageList.add( bean );
      }
      rs.close();
    }
    catch( SQLException sqlx )
    {
      showError(  request, response, "Cannot retrieve records" );
      return;
    }
    
    // Place the collection into menory...
    HttpSession session = request.getSession( true );
    request.setAttribute( "messagelist", messageList );
    
    // Delegate to JSP for the presentation...
    RequestDispatcher rd = context.getRequestDispatcher( "/ViewMessages2.jsp" );
    rd.forward( request, response );
    
  }
JSP
<html>

<head>
		
	<title>Online Communication Forum - View Messages</title>
	
	<link rel="stylesheet" href="OnlineForum.css" />
	
</head>
	
<body>

<%@page import="java.util.*"%>
<%@page import="java.sql.*" %>
<%@page import="OnlineForum.TinOfBeans.MessageBean"%>


<div class="outer">
	<div class="banner"><h1>Online Communication Forum</h1>
	<p /></div> <!-- end banner -->
		<div class="header"><h2 align="left"><a href="ViewMessages2.jsp">View Messages</a>  |  <a href="PostMessage.jsp">Post Message</a>  |  <a href="Logout.jsp">Logout</a></h2></div> <!-- end header -->
		<div class="inner">
	

		
		<table>
			<%
				List list = (List)session.getAttribute("messagelist");
				
				if( list.size() == 0 )
				{
				%>
				<tr><td>Sorry, no messages have been returned.</td></tr>
				<%
				return;
								
				}
				
				
				for( int i=0; i < list.size(); i++)
				{
					MessageBean bean = (MessageBean)list.get(i);

				%>
				<TD align=center><dd><A HREF="servlet/MessageController?action=viewmessages&messageID=<%=bean.getMessageID()%>"><%=bean.getMessageID()%></A></td>
				<td><A HREF="servlet/MessageController?action=viewmessages&messageID=<%=bean.getMessageID()%>"><%=bean.getUserID()%></a></td>
				<td><A HREF="servlet/MessageController?action=viewmessages&messageID=<%=bean.getMessageID()%>"><%=bean.getSubject()%></a></td>
				<td><A HREF="servlet/MessageController?action=viewmessages&messageID=<%=bean.getMessageID()%>"><%=bean.getDateposted()%></a></td>
			</tr>
			<%
				}
			%>
			
		</table>
		
		
	</div><!-- end inner -->
	</div><!-- end outer -->
</BODY>
</HTML>
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Post Details
Locked on Nov 22 2008
Added on Oct 23 2008
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