Class Not Found Issues

Preface

This page discusses the various ways you see Class Not Found errors or very similar errors. It is strongly advised you read the following topics:

• Classloader HOWTO pages: Tomcat 7.0, Tomcat 6.0.
• Don't use packageless classes and declare all imported classes!
• Another answer to a classloader issue

If you get a NoClassDefFoundError exception, the root cause might be the same as for a ClassNotFound exception.

Questions

1. Why is jsp:useBean is not working?
2. Why do I get java.lang.NoClassDefFoundError: javax/servlet/Filter?
3. Why do I get java.lang.NoClassDefFoundError: org/xml/sax/InputSource?

Answers

 jsp:useBean 

...

• Your bean is packaged in a class.

• You have fully qualified your class name (e.g.:

  No Format
  com.bar.package.MyClass

  ) OR

• You have imported your class into your jsp (e.g.:

  No Format
  <%@ page import="com.bar.package.MyClass"%>

  )

 java.lang.NoClassDefFoundError: javax/servlet/Filter

...

You have conflicting XML api jar files in your classpath. Read the README or RELEASE-NOTES for more information.CategoryFAQ