Understanding error messages from console...help please

Question

Hi,
I am getting there...almost...my classes compiled...so far so good...
However, when I hit the "Submit" button (class Booking) the program seems to get stuck on something ...and I don't how to understand the error message:
Here is the error message, underneath are the two classes involved (code):
D:\JBuilder8\jdk1.4\bin\appletviewer.exe Booking.html
java.lang.NumberFormatException: null
     at java.lang.Integer.parseInt(Integer.java:394)
     at java.lang.Integer.parseInt(Integer.java:476)
     at Order.getPeople(Order.java:57)
     at ConfirmationPopup.<init>(ConfirmationPopup.java:72)
     at DetailsPopup.actionPerformed(DetailsPopup.java:152)
     at java.awt.Button.processActionEvent(Button.java:381)
     at java.awt.Button.processEvent(Button.java:350)
     at java.awt.Component.dispatchEventImpl(Component.java:3598)
     at java.awt.Component.dispatchEvent(Component.java:3439)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:450)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:197)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:144)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)
import java.awt.*;
import java.awt.event.*;
import java.util.StringTokenizer;
public class DetailsPopup extends Frame implements ActionListener,ItemListener
  TextField SName;
  TextField FName;
  TextField Email;
  TextField CCard;
  Choice ChoiceExpMonth;
  Choice ChoiceExpYear;
  Color LightBlue = new Color(180,180,255);
  String a6;
  String a7;
  String a8;
  String a4 = "1";
  String a5 = "2003";
  public DetailsPopup(String f,String co,String pr,String pe)
    super(f);
    a6 = co;
    a7 = pr;
    a8 = pe;
    Button b3 = new Button ("Submit");
    b3.addActionListener(this);
    Panel panel = new Panel();
    panel.setBackground(Color.yellow);
    panel.add(b3);
    add("South", panel);
    Panel fieldPanel = new Panel();
    fieldPanel.setBackground(LightBlue);
    fieldPanel.setLayout(new GridLayout(0,1));
    panel = new Panel();
    panel.add(new Label("Surname"));
    SName = new TextField(15);
    panel.add(SName);
    fieldPanel.add(panel);
    panel = new Panel();
    panel.add( new Label("First Name"));
    FName = new TextField(15);
    panel.add(FName);
    fieldPanel.add(panel);
    panel = new Panel();
    panel.add( new Label("E-mail"));
    Email = new TextField(15);
    panel.add(Email);
    fieldPanel.add(panel);
    panel = new Panel();
    panel.add( new Label("Credit/Debit Card"));
    CCard = new TextField(16);
    panel.add(CCard);
    fieldPanel.add(panel);
    panel = new Panel();
    panel.add( new Label("Expiry Date"));
    panel.add( new Label("Month"));
    ChoiceExpMonth = new Choice();
    ChoiceExpMonth.addItemListener(this);
    panel.add(ChoiceExpMonth);
    fieldPanel.add(panel);
    int i = 1;
    while (i < 13)
      ChoiceExpMonth.addItem(new Integer(i).toString());
      i++;
    panel = new Panel();
    panel.add(new Label("Year"));
    ChoiceExpYear = new Choice();
    ChoiceExpYear.addItemListener(this);
    panel.add(ChoiceExpYear);
    fieldPanel.add(panel);
    int j = 2003;
    while (j < 2008)
      ChoiceExpYear.addItem(new Integer(j).toString());
      j++;
    add(fieldPanel, "Center");
    setSize(400, 300);
    setLocation(320,240);
    setVisible(true);
    //addWindowListener(new WindowAdapter() {
      //public void windowClosing(WindowEvent e) {
        //System.exit(0);
  public void itemStateChanged(ItemEvent e) //read choice from ChoiceExpMonth and/or ChoiceExpYear DropDowns
   if (e.getSource().equals (ChoiceExpMonth))
     a4 = (String) e.getItem();  // When ChoiceExpMonth is modified
   if (e.getSource().equals (ChoiceExpYear))
     a5 = (String) e.getItem();  // When ChoiceExpYear is modified
  public void actionPerformed( ActionEvent e)
    String Name = "";
    String First = "";
    String Card = "";
    String Mail = "";
    String TestEmail = Email.getText();
    StringTokenizer st = new StringTokenizer(TestEmail,"@");
    if (SName.getText().length() == 0)
      Name = "bad";
    if (FName.getText().length() == 0)
      First = "bad";
    if (CCard.getText().length() != 16)
      Card = "bad";
    if(TestEmail.indexOf("@") == -1)
      System.out.println("TestEmail has no '@' symbol");
    if (st.countTokens() != 2)
      Mail = "bad";
    if (Name.equals("bad") || First.equals("bad") || Card.equals("bad") || Mail.equals("bad"))
     Dialog Err = new Erratum (new Frame (),Name,First,Card,Mail);
    else
     dispose();
     String a0 = SName.getText();
     String a1 = FName.getText();
     String a2 = Email.getText();
     String a3 = CCard.getText();
     ConfirmationPopup Conf = new ConfirmationPopup(new Frame(),a0,a1,a2,a3,a4,a5,a6,a7,a8);
    //System.out.println("Name = " + Name + "\n" +
                       //"First = " + First + "\n" +
                       //"Card = " + Card + "\n" +
                       //"Mail = " + Mail);
  //public static void main(String[] args) {
    //new DetailsPopup("Chaos!");
class ConfirmationPopup
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.awt.Dialog.*;
class ConfirmationPopup extends Dialog implements ActionListener
Dialog Confirmation;
Color LightBlue = new Color(180,180,255);
ConfirmationPopup(Frame f,String a0,String a1,String a2,String a3,String a4,String a5,String a6,String a7,String a8)
   super(f);
   String SName = a0;
   String FName = a1;
   String Email = a2;
   String CCard = a3;
   String ExpMonth = a4;
   String ExpYear = a5;
   String Course = a6;
   String Price = a7;
   String People = a8;
   String[] c = {SName,FName,Email,CCard,ExpMonth,ExpYear,Course,Price,People};
   Order order1 = new Order(c);  
   Button b6 = new Button ("OK"); //OK
   b6.addActionListener(this);
   Panel panel = new Panel();
   panel.setBackground(LightBlue);
   panel.add(b6);
   add("South", panel);
   Panel Datapanel = new Panel();
   Datapanel.setBackground(LightBlue);
   Datapanel.setLayout(new GridLayout(0,1));
   panel = new Panel();
   panel.add( new Label("Surname:"));
   panel.add( new Label(order1.getSName()));
   Datapanel.add(panel);
   panel = new Panel();
   panel.add( new Label("First Name:"));
   panel.add( new Label(order1.getFName()));
   Datapanel.add(panel);  
   panel = new Panel();
   panel.add( new Label("E-mail:"));
   panel.add( new Label(order1.getEmail()));
   Datapanel.add(panel);
   panel = new Panel();
   panel.add( new Label("Credit/Debit Card:"));
   panel.add( new Label(order1.getCCard()));
   Datapanel.add(panel);
   panel = new Panel();
   panel.add( new Label("Expiry Date:"));
   panel.add( new Label(order1.getExpMonth() +"/" +order1.getExpYear()));
   Datapanel.add(panel);
   panel = new Panel();
   panel.add( new Label("Course booked:"));
   panel.add( new Label(order1.getCourse()));
   Datapanel.add(panel);
   panel = new Panel();
   panel.add( new Label("Number of persons:"));
   panel.add( new Label(new Integer(order1.getPeople()).toString()));
   Datapanel.add(panel);
   panel = new Panel();
   panel.add( new Label("Total Cost of your order"));
   panel.add( new Label(new Integer(order1.getTotal()).toString()));
   Datapanel.add(panel);
   add(Datapanel, "Center");
   setSize(400,300);
   setLocation(320,240);
   setTitle("Order Confirmation");
   pack();
public void actionPerformed( ActionEvent e)
   dispose();

Answer 1

here is also the class Order
import java.util.*;
public class Order
private String[] OrderDetails = new String[9]; //create array 9 elements
Order(String[] c)
   this.OrderDetails = c;
String getSName()  //return Surname
   String s = OrderDetails[0];
   return s;
String getFName()  //return First Name
   String f = OrderDetails[1];
   return f;
String getEmail() //return E-mail
   String email = OrderDetails[2];
   return email;
String getCCard() //return CCard number
   String cc = OrderDetails[3];
   return cc;
String getExpMonth() //return CCard Expiry Month
   String expm = OrderDetails[4];
   return expm;
String getExpYear() //return CCard Expiry Year
   String expy = OrderDetails[5];
   return expy;
String getCourse() //return Course's name
   String course = OrderDetails[6];
   return course;
int getPrice() //return Price (Full-Time, Part-Time, Concessions)
   String price1 = OrderDetails[7];
   int price = Integer.parseInt(price1);  
   return price;
int getPeople() //return number of participants
   String people1 = OrderDetails[8];
   int people = Integer.parseInt(people1);
   return people;
int getTotal() //return total cost of booking
   int Total = getPrice()*getPeople();
   return Total;
}