Re: HTTP 500 Tomcat help

Nigel Wade <>
Mon, 29 Jan 2007 10:16:05 +0000
<epkhh5$k7p$> wrote:


I'm getting an HTTP 500 Status error using Apache Tomcat. I'm
learning Servlets and JSPs from the Head First book. I've searched
the groups and on the Internet, and can't seem to resolve my problem.

I have a webpage, form.html, that displays just fine with http://
localhost:8080/beer-V1/form.html. This web page is mapped in web.xml
to /

- <servlet>
  <servlet-name>Ch3 Beer</servlet-name>
- <servlet-mapping>
  <servlet-name>Ch3 Beer</servlet-name>
  </web-app> maps the BeerSelect servlet class, which controls the
BeerExpert model.

package com.example.web;

import com.example.model.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;

public class BeerSelect extends HttpServlet {

      public void doPost(HttpServletRequest request, HttpServletResponse
                              throws IOException, ServletException {

              PrintWriter out = response.getWriter();
              out.println("Beer Selection Advice<br>");
              String c = request.getParameter("color");

              BeerExpert be = new BeerExpert();
              List result = be.getBrands(c);
              Iterator it = result.iterator();
              while (it.hasNext()) {
                      out.println("<br>try: " +;
      } //end doPost
} //end class


When I hit the submit button on form.html, I get this HTTP 500 error:
java.lang.NoClassDefFoundError: com/example/web/BeerSelect (wrong
name: BeerSelect)

I think that that message means that the class file which the classloader has
found in com/example/web/BeerSelect.class doesn't actually contain the class
for com.example.web.BeerSelect, but rather the class BeerSelect. Is there any
chance that the file contains an old version of the class which didn't have the
correct package declaration? Have a look at the contents of the class file
using javap, and see what it says for the class package.

Nigel Wade, System Administrator, Space Plasma Physics Group,
            University of Leicester, Leicester, LE1 7RH, UK
E-mail :
Phone : +44 (0)116 2523548, Fax : +44 (0)116 2523555

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