usage of extends directive in eclipse

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JSP

I am developing a web based project using eclipse in jsp. Now i need to extends one class to another.

I wrote the following code to extend a class in jsp

<%@ page extends="packagename.sample" %>
<%= sum(10,20)%>


But it is showing error as follows


An error occurred at line: 22 in the generated java file
The method getServletConfig() is undefined for the type First_jsp

An error occurred at line: 23 in the generated java file
The method getServletConfig() is undefined for the type First_jsp


Can anybody suggest how to extend one class into another using eclipse.....