Currently I'm using netbeans 7.2 using glassfish server. I want to put two numbers using HTML+ Servelet. I'm just a beginner I have no idea. Would somebody help me? I also don't know why I got error: Incompatible types required int found string although I used parseInt to convert String into Integer. Here's the code:

INDEX.JSP:

<%-- 
    Document   : index
    Created on : Oct 3, 2012, 4:06:09 PM
    Author     : len
--%>

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <form="add/addpackage">
            Name:<input type="text" name="name" value="" />
            Num1:<input type="text" name="num1" value="" />
            Num2:<input type="text" name="num2" value="" />
            <br>
            <input type="submit" value="button" />
        </form>
    </body>
</html>

Servelet:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

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;

/**
 *
 * @author len
 */
@WebServlet(name = "HelloServelet", urlPatterns = {"/HelloServelet"})
public class HelloServelet extends HttpServlet {

    /**
     * Processes requests for both HTTP
     * <code>GET</code> and
     * <code>POST</code> methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();

            String name = request.getParameter("name");
            int a = request.getParameter("num1");
            int b = request.getParameter("num2");
            int sum = 0;

            int x,y;

            x = Integer.parseInt(a);
            y = Integer.parseInt(b);

            sum = x + y;

            out.println("Hi!" + name + "The sum is" + sum);     
            out.close();
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP
     * <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP
     * <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}

int a = request.getParameter("num1");
int b = request.getParameter("num2");

here a and b are integer variable,
request.getparameter() method will return integer value,
change those variable type as string

Integer.parseInt

this method reuqires string as argument

request.getParameter() method returns the value in string.

So you have to take String object to store the value of that text field instead of int a write String a and String b.

Then convert into integer using INTEGER.parseInt(a) and then add both.

Thank you.