Q:

ClassNotFound exception in struts 2

<filter>
    <filter-name>struts2</filter-name>
    <filter-class>apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
<session-config>
    <session-timeout>
        30
    </session-timeout>
</session-config>
<welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
</welcome-file-list>

javax.servlet.ServletException:
  PWC1243: Filter execution threw an
  exception
  java.lang.ClassNotFoundException:
  apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter

Exception comes when I run the JSP page.

A:

It was more easy  to check that that class existed (looking inside your jar, or just googling) than writing a question here, but...
You missed the org. prefix:  org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter

