Jsp – What causes this jsp Error 500

jspservletstomcat

I wrote a very simple jsp problem that gets a number from a class and show it but I encountered error 500.

I use eclipse with tomcat 5.5:

 <%@page import="java.io.IOException"%>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!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>Insert title here</title>
</head>
<h1>number of shown :</h1>
<body>
<%
try{
out.print(Model.getCount());
}
catch(IOException k)
{
    out.println("Eror");
}
%>
</body>
</html>

my Model class=>

public class Model {
    static int number=0;
    public static int getCount()
    {
        number++;
        return number;
    }
}

any my model class is default package.

The error I see:

type Exception report

message

description The server encountered an
internal error () that prevented it
from fulfilling this request.

exception

org.apache.jasper.JasperException:
Unable to compile class for JSP:

An error occurred at line: 14 in the
jsp file: /show.jsp Model cannot be
resolved 11: 12: <% 13: try{
14: out.print(Model.getCount()); 15: }
16: catch(IOException k) 17: {

Stacktrace:
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:93)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:330)
org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:451)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:328)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:307)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:295)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:565)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:309)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

note The full stack trace of the root
cause is available in the Apache
Tomcat/5.5.33 logs.

Apache Tomcat

Best Answer

Never put any class in the default package. The default package is not accessible to classes in a package, and since the JSP is transformed in a servlet class by Tomcat, and this class is in a package, it can't access your Model class.

Once it's in a well-defined package, you'll have to import it, as mschonaker shows in his answer:

<%@page import="somepackage.Model"%>
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