Applet Code Error

[Linda Weeks]

When I try to run DonnaApplet, the appletviewer screen comes up and I'm able to feed in the name and numbers but when I click Submit Scores I get this error message:
A:\>appletviewer DonnaApplet.html
Exception occurred during event dispatching:
java.lang.NumberFormatException:
at java.lang.Integer.parseInt(Compiled Code)
at java.lang.Integer.parseInt(Integer.java:458)
at DonnaApplet.actionPerformed(DonnaApplet.java:126)
at java.awt.AWTEventMulticaster.actionPerformed(AWTEventMulticaster.java
:351)
at java.awt.Button.processActionEvent(Button.java:308)
at java.awt.Button.processEvent(Button.java:281)
at java.awt.Component.dispatchEventImpl(Compiled Code)
at java.awt.Component.dispatchEvent(Compiled Code)
at java.awt.EventQueue.dispatchEvent(Compiled Code)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:68)
Here's my code:

<font size=2.5>
/*
  Project 4Arrays
  Programmer:Linda Weeks
  Date:November 19, 2001
  Program Name:DonnaApplet
*/
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class DonnaApplet extends Applet implements ActionListener
{
    //Declaring Variables
    String firstName, lastName;
    int size, content, delivery, organization, rank;
    int i = 1;
    float totalContent = 0;
    float totalDelivery = 0;
    float totalOrganization = 0;
    float totalRank = 0;
    Person[] debateGroup = new Person[50];
    //Create components for applet
    Label headerLabel = new Label("Please enter forensic score data");
    Label firstNameLabel = new Label ("First Name:");
TextField firstNameField = new TextField(15);
    Label lastNameLabel = new Label ("Last Name:");
TextField lastNameField = new TextField(15);
    Label contentLabel = new Label ("Content Score:");
Choice contentChoice = new Choice();
    Label deliveryLabel = new Label ("Delivery Score:");
Choice deliveryChoice = new Choice();
    Label organizationLabel = new Label ("Organization Score:");
Choice organizationChoice = new Choice();
    Label rankLabel = new Label ("Rank:");
TextField rankField = new TextField(4);
    Button submitButton = new Button("Submit Scores");
    Button displayButton = new Button("Display Averages");
    Label avgContentLabel = new Label ("Average Content:");
      Label displayAvgContentLabel = new Label("");
    Label avgDeliveryLabel = new Label ("Average Delivery:");
      Label displayAvgDeliveryLabel = new Label("");
    Label avgOrganizationLabel = new Label ("Average Organization:");
      Label displayAvgOrganizationLabel = new Label("");
    Label avgRankLabel = new Label ("Average Rank:");
      Label displayAvgRankLabel = new Label("");
  public void init()
  {
    //Add components to window and set colors
    setBackground(Color.green);
    add(headerLabel);
    add(firstNameLabel);
    add(firstNameField);
firstNameField.requestFocus();
    add(lastNameLabel);
    add(lastNameField);
    add(contentLabel);
    add(contentChoice);
contentChoice.addItem("1");
contentChoice.addItem("2");
contentChoice.addItem("3");
contentChoice.addItem("4");
contentChoice.addItem("5");
    add(deliveryLabel);
    add(deliveryChoice);
deliveryChoice.addItem("1");
deliveryChoice.addItem("2");
deliveryChoice.addItem("3");
deliveryChoice.addItem("4");
deliveryChoice.addItem("5");
    add(organizationLabel);
    add(organizationChoice);
organizationChoice.addItem("1");
organizationChoice.addItem("2");
organizationChoice.addItem("3");
organizationChoice.addItem("4");
organizationChoice.addItem("5");
    add(rankLabel);
    add(rankField);
    add(submitButton);
submitButton.addActionListener(this);
    add(displayButton);
submitButton.addActionListener(this);
    add(avgContentLabel);
    add(displayAvgContentLabel);
    add(avgDeliveryLabel);
    add(displayAvgDeliveryLabel);
    add(avgOrganizationLabel);
    add(displayAvgOrganizationLabel);
    add(avgRankLabel);
    add(displayAvgRankLabel);
}
  public void actionPerformed(ActionEvent e)
  {
    String arg = e.getActionCommand();
    if (arg == "Submit Scores")
    {
//Assigning data
firstName = firstNameField.getText();
lastName = lastNameField.getText();
content = Integer.parseInt(contentChoice.getSelectedItem());
delivery = Integer.parseInt(deliveryChoice.getSelectedItem());
organization = Integer.parseInt(organizationChoice.getSelectedItem());
rank = Integer.parseInt(rankField.getText());
size = i++;
debateGroup[i] = new Person(firstName, lastName, content, delivery, organization, rank);
//Accumulate totals for each category
totalContent += debateGroup[i].getContent();
totalDelivery += debateGroup[i].getDelivery();
totalOrganization += debateGroup[i].getOrganization();
totalRank += debateGroup[i].getRank();
//Reset text fields and choice boxes
firstNameField.setText("");
lastNameField.setText("");
contentChoice.select(0);
deliveryChoice.select(0);
organizationChoice.select(0);
rankField.setText("");
firstNameField.requestFocus();
    }
    if (arg == "Display Averages")
    {
    
displayAvgContentLabel.setText(String.valueOf(totalContent/size));
displayAvgDeliveryLabel.setText(String.valueOf(totalDelivery/size));
        displayAvgOrganizationLabel.setText(String.valueOf(totalOrganization/size));
        displayAvgRankLabel.setText(String.valueOf(totalRank/size));
repaint();
    }
  }
}

Thanks
Linda

[This message has been edited by Cindy Glass (edited December 03, 2001).]

[Paul Stevens]

In your init() method you do this line twice:
submitButton.addActionListener(this);
The second one should be
displayButton.addActionListener(this);
You still need to put error checking in for the rank textfield in case a non number is entered in or nothing at all.
What is currently happening is the action listers actionPerformed() is being fired twice for every click. The second time in the textfield contains nothing so you get the exception. Which is why you need to put in error checking.