java.lang.NoClassDefFoundError

here is index.jsp

<%@ 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>

<body>
<form action="welcome" method="post">
<table align="left">
 <tr><td>Name<input type="text" name="name"></td></tr>
 <tr><td>Age<input type="text" name="age"></td></tr>
 <tr><td>City<input type="text" name="city"></td></tr>
 <tr><td>Course<input type="text" name="course"></td></tr>
<tr><td>username<input type="text" name="username"></td></tr>
<tr><td>password<input type="text" name="password"></td></tr>
<tr><td><input type="submit" name="action" value="New" width=50/></td></tr> 
</table>
</form>

<form action="welcome" method="post">
<table align="right">
<tr><td>username<input type="text" name="username"></td></tr>
<tr><td>password<input type="text" name="password"></td></tr>
<tr><td><input type="submit" name="action" value="Old" width=50/></td></tr> 
</table>
</form>

</body>
</html>

this is welcomeprocessor

package voter.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import voter.bean.student;
import voter.db.hibernateClass;

public class WelcomeProcessor extends GenericProcessors {
	
       
   
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		this.doGet(request, response);
	}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		/*if(!isUserPresent(request)){
			response.sendRedirect("error.jsp");
		}
		*/
		PrintWriter out=response.getWriter();
		out.println("DOPOST");
		
		String action=request.getParameter("action");
		
		
		
		if(action.equals("New")){
			out.println("NEWWWWWWWW "+action);
			String name=request.getParameter("name");
			String age=request.getParameter("age");
			String city=request.getParameter("city");
			String course=request.getParameter("course");
			String username=request.getParameter("username");
			String password=request.getParameter("password");
			
			//dbHandler.addStudent(name, age, city, course, username, password);
			student s=new student();
			s.setName(name);
			s.setAge(age);
			s.setCity(city);
			s.setCourse(course);
			s.setPassword(password);
			s.setUsername(username);
			
			hibernateClass h=new hibernateClass();
			h.save(s);
		}
		else if(action.equals("Old")){
			
			out.println("OLDDDDDDD "+action);
			
			String username=request.getParameter("username");
			String password=request.getParameter("password");
			
			boolean checkStudent=dbHandler.checklogin(username, password);
			if(checkStudent){
				addUser(username, request);
				out.println("User is authenticated");
				//response.sendRedirect("welcome.jsp");
			}
			else{
				out.println("User is not authenticated");
			}
		}
	}

}

this is student bean class

this is the error

but why welcomeprocessor need session class???

Hi

WelcomeProcessor is creating a new instance of hibernateClass. Since hibernateClass is using the Session class, welcomeprocessor is indirectly dependent on Session. Include the hibernate jar in your war file.

Thanks!

i am using eclips.
i added the hibernate3.jar to lib folder at WEB-INF.
anyway now nullpointer exception

session null means it is not created the sessionFactory .why it is not created ?
this is my hbm file

this is my config file

i think there is some confuse with generato element in hbm file.because there is no any long values in object.All are String .then i add generator as String .is it wrong?