HO un problema con una servlet ,che ho copiato da un corso , però non funziona ecco la jsp:

codice:
<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
<%@ page import="java.util.Date" %>
<!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=UTF-8">
<title>Data odierna</title>
</head>
<body>
<% Date data= new Date(); %>

<h1>La data di oggi è : <%=data.toLocaleString() %></h1>

<form action="HelloRequest" method ="post">

Nome: <input type="text" name="nome"></br>
Cognome: <input type="text" name="nome"></br>
 <input type="submit" value="invia">
 </form>

</body>
</body>
</html>
e la servlet
codice:
	package Esempio;

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

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

/**
 * Servlet implementation class HelloRequest
 */
@WebServlet("/HelloRequest")
public class HelloRequest extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public HelloRequest() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request,response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out=response.getWriter();
		String nome =request.getParameter("nome").toString();
		String cognome =request.getParameter("cognome").toString();
		out.println("<html>");
		out.println("<head>");
		out.println("<title>Primo esempio Servlet");
		out.println("</title>");
		out.println("<body>");
		
		out.println("Benvenuto "+nome+" "+cognome+"");

		out.println("</body>");
		out.println("</html>");

	}

}
La jsp funziona ma quando inserisco i dati e clicco su invia ho:

codice:
mag 11, 2013 7:33:20 PM org.apache.catalina.core.AprLifecycleListener init
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /usr/java/packages/lib/amd64:/usr/lib/jni:/lib:/usr/lib
mag 11, 2013 7:33:20 PM org.apache.tomcat.util.digester.SetPropertiesRule begin
WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:Sito' did not find a matching property.
mag 11, 2013 7:33:20 PM org.apache.tomcat.util.digester.SetPropertiesRule begin
WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:Web1' did not find a matching property.
mag 11, 2013 7:33:20 PM org.apache.tomcat.util.digester.SetPropertiesRule begin
WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:CorsoDoc' did not find a matching property.
mag 11, 2013 7:33:20 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-bio-8081"]
mag 11, 2013 7:33:20 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]
mag 11, 2013 7:33:20 PM org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 1459 ms
mag 11, 2013 7:33:20 PM org.apache.catalina.core.StandardService startInternal
INFO: Starting service Catalina
mag 11, 2013 7:33:20 PM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet Engine: Apache Tomcat/7.0.39
mag 11, 2013 7:33:25 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-bio-8081"]
mag 11, 2013 7:33:25 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
mag 11, 2013 7:33:25 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 4469 ms
mag 11, 2013 7:33:36 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [Esempio.HelloRequest] in context with path [/CorsoDoc] threw exception
java.lang.NullPointerException
	at Esempio.HelloRequest.doPost(HelloRequest.java:41)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:722)