instantiating objects in servlets

[davidr69]

I am completely new to servlets. I have an extensive programming background (C, C++, assembler, PHP, python, javascript, others) and I am trying to get into servlet programming. I have done several jsp's and small java apps, and I have code that works both as a java app and as a jsp:

class foobar {
        int x = 0;
        public void foobar() { }
}
 
public class mytest {
        public static void main(String[] args) {
                foobar blah = new foobar();
        }
}

No problem when I compile and run. Even as a jsp, it's not a problem:

<%
class foobar {
        int x = 0;
        public void foobar() { }
}
 
foobar blah = new foobar();
%>

That also works perfectly fine. When I try to do it as a servlet, Tomcat complains:

exception

javax.servlet.ServletException: Servlet execution threw an exception

root cause

java.lang.NoClassDefFoundError: foobar
mytest.doGet(datacenter_matrix.java:160)
javax.servlet.http.HttpServlet.service(HttpServlet .java:690)
javax.servlet.http.HttpServlet.service(HttpServlet .java:803)

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
 
class foobar {
    int x = 0;
    public void foobar() { }
}
 
public class mytest extends HttpServlet {
    public void doGet(HttpServletRequest req, HttpServletResponse res)
                    throws ServletException, IOException {
 
        foobar blah = new foobar();
    }
}

I searched the web all day yesterday and couldn't find why my object won't instantiate within my servlet. The servlet works so long as I don't try to instantiate a foobar object. Any idea?!?

[JosAH]

Your servlet does want to instantiate the objects but it can't find the appropriate class(es). Check your documentation for your servlet container: it mentions where you are supposed to store your classes (stored in a jar or just a .class file).

btw, a constructor doesn't have a return type; remove that 'void' type from your attempt of a constructor.

kind regards,

Jos