Java.lang.NullPointerException in a servlet

Question

I'm having a problem, and need help as quick as I can get it.
I'm coding a program that takes input from an HTML file, gives it to a servlet, which processes the information and spits it back out to the web browser in HTML.
I'm using NetBeans 3.6 with Java 1.5.0.
The error that TomCat is giving me is:
java.lang.NullPointerException
     java.util.Hashtable.get(Hashtable.java:333)
     org.apache.tomcat.util.http.Parameters.getParameterValues(Parameters.java:231)
     org.apache.tomcat.util.http.Parameters.getParameter(Parameters.java:276)
     org.apache.coyote.tomcat5.CoyoteRequest.getParameter(CoyoteRequest.java:1094)
     org.apache.coyote.tomcat5.CoyoteRequestFacade.getParameter(CoyoteRequestFacade.java:312)
     org.netbeans.modules.web.monitor.server.MonitorRequestWrapper.getParameter(MonitorRequestWrapper.java:177)
     edu.usf.CCC.doPost(CCC.java:57)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
     org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:305)I don't understand why it's giving me the NullPointerException at the first "request.getParamter(name)" line, but it is.
Any Suggestions?
My servlet code:
package edu.usf;
import java.net.*;
import java.lang.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
public class CCC extends HttpServlet {
  float drive_cost = 0.00f;
  float engine_cost = 0.00f;
  float sunroof_cost = 0.00f;
  float brakes_cost = 0.00f;
  float interior_cost = 0.00f;
  float style_cost = 0.00f;
  float roofrack_cost = 0.00f;
  String name,style,engine,drive,brakes,interior,sunroof,roofrack,basecost,totalcost;
  String namevar,stylevar,enginevar,drivevar,brakesvar,interiorvar,sunroofvar,roofrackvar,basecostvar,totalcostvar;
  String namastr,stylestr,enginestr,drivestr,brakesstr,interiorstr,sunroofstr,roofrackstr,basecoststr,totalcoststr;
  String name_field,style_option,engine_option,brakes_option,drive_option,interior_option;
  float base_cost = 15000.00f;
  float total_cost = base_cost;
  //static final String CONTENT_TYPE = "text/html";
  public void init() throws ServletException {
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {
  response.setContentType( "text/html" );
  PrintWriter out = response.getWriter();
  namevar = request.getParameter(name);
  stylevar = request.getParameter(style);
  enginevar = request.getParameter(engine);
  drivevar = request.getParameter(drive);
  brakesvar = request.getParameter(brakes);
  interiorvar = request.getParameter(interior);
  sunroofvar = request.getParameter(sunroof);
  roofrackvar = request.getParameter(roofrack);   
  //Time to do some work
  //Check to see what style of car was selected.
  { if ( stylevar.equals("hatch") )
      {style_option = "Hatchback";
      style_cost = 0.00f;}
     if ( stylevar.equals("sedan") )
      {style_option = "Sedan";
      style_cost = 800.00f;}
     if ( stylevar.equals("wagon") )
      {style_option = "Wagon";
      style_cost = 1400.00f;}
  //Drivetrain calculation time
    { if ( drivevar.equals("2") )
      {drive_option = "2-Wheel Drive";
       drive_cost = 0.00f;}
      else if (drivevar.equals("4") )
       drive_option = "4-Wheel Drive";
       drive_cost = 7000.00f;}
   //Engine calculation time
    { if ( enginevar.equals("4"))
      {engine_option = "4-Cylinder";
       engine_cost = 0.00f;}
      else if ( enginevar.equals("6"))
      {engine_option = "6-Cylinder";
       engine_cost = 2200.00f;}
   //Brake calculation time
    { if ( brakesvar.equals("s") )
       {brakes_option = "Standard";
        brakes_cost = 0.00f;}
      else if ( brakesvar.equals("a") )
        {brakes_option = "Anti-Lock";
         brakes_cost = 900.00f;}
   //Sunroof calculation time
    { if ( sunroofvar.equals("1") )
        sunroof_cost = 800.00f;
   //Interior calculation time
    { if ( interiorvar.equals("deluxe"))
      {interior_option = "Deluxe";
      interior_cost = 0.00f;}
    { if ( interiorvar.equals("luxury") )
      {interior_option = "Luxury";
      interior_cost = 800.00f;}
    { if ( interiorvar.equals("executive") )
      {interior_option = "Executive";
      interior_cost = 1400.00f;}
   //Roofrack calculation time
    { if ( roofrackvar.equals("1") )
        roofrack_cost = 200.00f;
   //Total cost calculation time
      total_cost = style_cost + drive_cost + engine_cost +  brakes_cost +
                sunroof_cost + interior_cost + roofrack_cost;
//OUTPUT HTML SECTION
    //Print up HTML Header section
    out.println("<html>");
    out.println("<head><title>Tri-C: Results</title></head>");
    out.println("<body bgcolor=\"#FFFFFF\">");
    out.println("<center>");
    out.println("<p>Tri-C: ResultsCar Calculation</p>");
    out.println("<table border=1>");
    out.println("<tr><td> </td><td>Option</td><td>Cost</td></tr>");
    //Print up name
    namastr = ("<tr><td>Name:</td><td>" + name + "</td></tr>");
    out.println(namastr);
    out.println("<tr><td> </td><td> </td><td> </td></tr>");
    //Print up Base Cost
    basecoststr = ("<tr><td>Base Cost:</td><td> </td><td>$" + base_cost + "</td></tr>");
    out.println(basecoststr);
    //Print up Style selection
    stylestr = ("<tr><td>Style:</td><td>" + style_option + "</td><td>$" + style_cost + "</td></tr>");
    out.println(stylestr);
    //Print up Engine selection
    enginestr = ("<tr><td>Engine:</td><td>" + engine_option + "</td><td>$" + engine_cost + "</td></tr>");
    out.println(enginestr);
    //Print up Drivetrain selection
    drivestr = ("<tr><td>Drivetrain:</td><td>" + drive_option + "</td><td>$" + drive_cost + "</td></tr>");
    out.println(drivestr);
    //Print up Brakes selection
    brakesstr = ("<tr><td>Brakes:</td><td>" + brakes_option + "</td><td>$" + brakes_cost + "</td></tr>");
    out.println(brakesstr);
    //Print up Sunroof Selection
    sunroofstr = ("<tr><td>Sunroof:</td><td> </td><td>$" + sunroof_cost + "</td></tr>");
    out.println(sunroofstr);
    //Print up Interior Selection
    interiorstr = ("<tr><td>Interior:</td><td>" + interior_option + "</td><td>$" + interior_cost + "</td></tr>");
    out.println(interiorstr);
    //Print up Roofrack Selection
    roofrackstr = ("<tr><td>Roofrack:</td><td> </td><td>$" + roofrack_cost + "</td></tr>");
    out.println(roofrackstr);
    //Print up Total Cost section
    out.println("<tr><td> </td></tr>");
    totalcoststr = ("<tr><td>Total Cost:</td><td> </td><td>$" + total_cost + "</td></tr>");
    out.println(totalcoststr);
    //Print up HTML Footer section
    out.println("</table>");
    out.println("</body>");
    out.println("</html>");
And here is the HTML file that calls it:
<html>
<head>
<title>Tri-C: Car Cost Calculator</title>
</head>
<body background="#000000">
<form action="CCC" method="post">
<center>
<table border=1>
<tr><td>Enter your name:</td><td><input type="text" name="name" /></td></tr>
<tr><td> </td><td> </td></tr>
<tr><td>Style:</td><td><SELECT name="style">
<OPTION SELECTED value="hatch">Hatchback</OPTION>
<OPTION value="sedan">Sedan (+$800.00)</OPTION>
<OPTION value="wagon">Wagon (+$1400.00)</OPTION>
</SELECT></td></tr>
<tr><td>Drivetrain:</td><td>
<input type="radio" name="drive" value="2">2-Wheel Drive</input><br>
<input type="radio" name="drive" value="4">4-Wheel Drive (+$7000.00)</input>
</td></tr>
<tr><td>Engine:</td><td>
<input type="radio" name="engine" value="4">4-Cylinder</input><br>
<input type="radio" name="engine" value="6">6-Cylinder (+$2200.00)</input>
</td></tr>
<tr><td>Brakes:</td><td>
<input type="radio" name="brakes" value="0">Standard</input><br>
<input type="radio" name="brakes" value="1">Anti-Lock (+$900.00)</input>
</td></tr>
<tr><td>Sunroof:</td><td>
<input type="checkbox" name="sunroof" value="1">Add Option (+$800.00)</input>
</td></tr>
<tr><td>Interior:</td><td><SELECT name="interior">
<OPTION SELECTED value="deluxe">Deluxe</OPTION>
<OPTION value="luxury">Luxury (+$800.00)</OPTION>
<OPTION value="executive">Executive (+$1400.00)</OPTION>
</SELECT></td></tr>
<tr><td>RoofRack:</td><td>
<input type="checkbox" name="roofrack" value="1">Add Option (+$200.00)</input>
</td></tr>
<tr><td></td><td><input type="SUBMIT" value="Process">    <input type="reset" name="Clear Form"></td></tr>
</form>
</body>
</html>

Answer 1

It's because name is null. You declared it but didn't initialize it, so it's null. What did you expect to happen there?
By the way, declaring instance variables in a servlet class is a bad practice. If you get two requests at the same time, they both share the same instance of the servlet so they are both accessing and updating the same variables. Make them local variables in your doPost() method and you should not have that problem.