Can't figure it out where this Exception comes from?

Question

I'm trying to make a little application with JSP. It's a homework. So, i have the index.jsp page, where the client enters his name, and if the client exists in the database, then it's making a forward to clientexists.jsp, with the attribute client saved in the session. Then, the client has to make a choice from 2 radio buttons, and depending it's choice, i need to show him his taxes to pay. But after his choice, I have this exception in the Console:

18: <INPUT TYPE="SUBMIT" NAME="buton2" VALUE="Continua"></form>
19: 
20: <%
21:     client = request.getAttribute("nume").toString();
22:     
23:     if (request.getParameter("buton2") != null)
24:     {


Stacktrace:] with root cause
java.lang.NullPointerException
    at org.apache.jsp.clientexists_jsp._jspService(clientexists_jsp.java:82)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:68)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:387)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:363)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:306)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:203)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:108)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:379)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:242)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:259)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:281)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

And in the web page, i have another one pointing to the same line:

org.apache.jasper.JasperException: An exception occurred processing JSP page /clientexists.jsp at line 21

Here is my index.jsp page:

<%@page import="dao.*"%>
<%@page import="model.*"%>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1" import="java.util.*,java.text.*,java.io.*"%>
<jsp:useBean id="rep" class="dao.RepositoryDb"></jsp:useBean>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Tax machine</title>
</head>
<body>

<div align="center">

<h1>Your name:</h1>
<form method="POST" action="index.jsp"><INPUT TYPE="TEXT"
    NAME="name"><BR>
<BR>
<INPUT TYPE="SUBMIT" NAME="buton" VALUE="Continua"></form>

</div>
<%
    if (request.getParameter("buton") != null)
    {
        String client = request.getParameter("name");

        if (rep.clientExists(client))
        {
            session.setAttribute("nume", client);
%>
            <jsp:forward page="clientexists.jsp"></jsp:forward>
<%
        }
        else
        {
%>
            <jsp:forward page="clientnotexists.jsp"></jsp:forward>
<%
        }
    }
%>

</body>
</html>

And the clientexists.jsp page:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
    <%! String client = null; %>
<jsp:useBean id="rep" class="dao.RepositoryDb"></jsp:useBean>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Choose your options</title>
</head>
<body>
<div align="center">

<form method="POST" action="clientexists.jsp">
<INPUT TYPE="RADIO" NAME="group" VALUE=paid" CHECKED>Paid taxes<BR>
<INPUT TYPE="RADIO" NAME="group" VALUE="unpaid">Unpaid taxes<BR>
<BR>
<INPUT TYPE="SUBMIT" NAME="buton2" VALUE="Continue"></form>

<%
    client = session.getAttribute("nume").toString();

    if (request.getParameter("buton2") != null)
    {
        String option = request.getParameter("group");

        if (option.equalsIgnoreCase("paid"))
        {
%>
            <%= rep.getImpozitePlatite(client).toString()%>
<%
        }
        else
        {
%>
            <%= rep.getImpoziteNeplatite(client).toString()%>
<%
        }
    }
%>
</div>
</body>
</html>

Could you help me please? Thanks

You should move your java code to a java class and just use your JSP to display values. For one thing: Java code is a lot easier to debug — Sean Patrick Floyd, Jan 05 '11 at 10:16
Thank you very much for you valuable comment. If you know a link with some example, it could be even better. Thank you — DaJackal, Jan 05 '11 at 10:23

score 3 · Accepted Answer · edited May 23 '17 at 10:33

3

It is here

request.getAttribute("nume").toString();

request.getAttribute("nume") seems null and you are invoking toString() over null

make it like

client = "SOME_DEFAULT_VALUE";
if(request.getAttribute("nume") != null){
client = request.getAttribute("nume").toString();
}

For Client.jsp the error is there because I&Compiler can't see the declaration of client variable

A suggestion

how-to-avoid-java-code-in-jsp-files

edited May 23 '17 at 10:33

Community

1
1

answered Jan 05 '11 at 10:16

jmj

237,923
42
401
438

This is incorrect. The error is not a null pointer in the jsp but a syntax exception causing a null pointer in the compiler. – LINEMAN78 Jan 05 '11 at 10:22
@LINEMAN78 That is for client.jsp – jmj Jan 05 '11 at 10:25

score 0 · Answer 2 · answered Jan 05 '11 at 10:22

0

Typo:

client = request.getAttribute("nume").toString();

Should be:

client = request.getAttribute("name").toString();

getAttribute() returns a null object because it can't find what you are asking it to find and you cant run toString() on null.

One other thing, your html does not need to be in all caps. It's still valid but it's ugly and makes your code look outdated.

Edit: As mentioned by the poster that got in just before myself, you would be wise to separate your application logic from your markup output, it makes things much easier to maintain. Your current design is fine for homework, but it would be less than ideal on a real project.

answered Jan 05 '11 at 10:22

rich97

2,809
2
28
34

And how about `Continua` is it a typo too? – Adeel Ansari Jan 05 '11 at 10:32
I doubt that it's really the strange *nume* that causes the NPE, because on `index.jsp` he sets exactly this attribute on session: `session.setAttribute("nume", client);`. – Andreas Dolk Jan 05 '11 at 10:35
If he instantiate as nume, it has no problem to try to request nume.. He's maybe from another country.. – Gondim Jan 05 '11 at 10:39

Can't figure it out where this Exception comes from?

2 Answers2