I need help in GUI

Question

Hi every one..
I need help in this class. I want to do a modification to the project AddGUI so that it will do subtraction, multiplication and division of two integre numbers, in addition to addition.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GUIAddition extends JFrame {
   private String output;
   private int number1, number2, sum;
   private JLabel number1Label, number2Label, sumLabel;
   private JTextField number1TextField, number2TextField;
   private JButton addButton, exitButton;
   private JTextArea textArea;
   public GUIAddition()   {
   super("Sum of Two Integer Numbers");
// Create an instance of inner class ActionEventHandler
   ActionEventHandler handler = new ActionEventHandler();
// set up GUI
   Container container = getContentPane();
   container.setLayout( new FlowLayout() );
   // set up Label Fields and Text Fields for number1
   number1Label = new JLabel( "Number1" );
   number1TextField = new JTextField( 10 );
   number1TextField.addActionListener( handler );
   container.add( number1TextField );
   container.add( number1Label );
   // for number2
   number2Label = new JLabel( "Number2" );
   number2TextField = new JTextField( 10 );
   number2TextField.addActionListener( handler );
   container.add( number2TextField );
   container.add( number2Label );
   // for sum
   sumLabel = new JLabel( "Sum" );
   textArea = new JTextArea( 1,10 );  // only output, no addAction
   textArea.setEditable( false );
   container.add( textArea );
   container.add( sumLabel );
   // set up Add Button
   addButton = new JButton( "Add" );
   addButton.addActionListener( handler );
   container.add( addButton );
   // set up Exit Button
   exitButton = new JButton( "Exit" );
   exitButton.addActionListener( handler );
   container.add( exitButton );
  }// end constructor
// Display The Sum of the Two Numbers in displayfield
   public void displayAddition() {
       textArea.setText(output);
  }// end display method
   public static void main( String args[] )   {
      GUIAddition window = new GUIAddition();
      window.setSize(500, 100);
      window.setVisible( true );
  }// end main
   private class ActionEventHandler implements ActionListener {
     public void actionPerformed(ActionEvent event) {
       // process Text Fields: number1 and number2 as well as Add Button events
       if (event.getSource() == number1TextField)
           number1 = Integer.parseInt(event.getActionCommand());
       else if (event.getSource() == number2TextField)
           number2 = Integer.parseInt(event.getActionCommand());
       else if (event.getSource() == addButton){
               sum = number1 + number2;
               output = "" + sum;
               System.out.println("The Result of adding number1: " + number1 +
               " and number2: " + number2 + " is: " + sum);
       // process Exit Button event
       else if (event.getSource() == exitButton) System.exit(0);
// Display Information
       displayAddition();
     } // end method actionPerformed
   }// end inner class ActionEventHandler
}  // end Class GUIAddition

Answer 1

I try to do it for subtraction, but it didn't work correctly.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GUIAddition extends JFrame {
   private String output;
   private int number1, number2, sum, sub;
   private JLabel number1Label, number2Label, sumLabel, subLabel;
   private JTextField number1TextField, number2TextField;
   private JButton addButton, subButton, exitButton;
   private JTextArea textArea;
   public GUIAddition()   {
   super("Sum of Two Integer Numbers");
// Create an instance of inner class ActionEventHandler
   ActionEventHandler handler = new ActionEventHandler();
// set up GUI
   Container container = getContentPane();
   container.setLayout( new FlowLayout() );
   // set up Label Fields and Text Fields for number1
   number1Label = new JLabel( "Number1" );
   number1TextField = new JTextField( 10 );
   number1TextField.addActionListener( handler );
   container.add( number1TextField );
   container.add( number1Label );
   // for number2
   number2Label = new JLabel( "Number2" );
   number2TextField = new JTextField( 10 );
   number2TextField.addActionListener( handler );
   container.add( number2TextField );
   container.add( number2Label );
   // for sum
   sumLabel = new JLabel( "Sum" );
   textArea = new JTextArea( 1,10 );  // only output, no addAction
   textArea.setEditable( false );
   container.add( textArea );
   container.add( sumLabel );
   // for sub
   subLabel = new JLabel( "Subtraction" );
   textArea = new JTextArea( 1,10 );  // only output, no addAction
   textArea.setEditable( false );
   container.add( textArea );
   container.add( subLabel );
   // set up Add Button
   addButton = new JButton( "Add" );
   addButton.addActionListener( handler );
   container.add( addButton );
   // set up Sub Button
    subButton = new JButton( "Subtraction" );
   subButton.addActionListener( handler );
   container.add( subButton );
   // set up Exit Button
   exitButton = new JButton( "Exit" );
   exitButton.addActionListener( handler );
   container.add( exitButton );
  }// end constructor
// Display The Sum of the Two Numbers in displayfield
   public void displayAddition() {
       textArea.setText(output);
  }// end display method
   public static void main( String args[] )   {
      GUIAddition window = new GUIAddition();
      window.setSize(500, 100);
      window.setVisible( true );
  }// end main
   private class ActionEventHandler implements ActionListener {
     public void actionPerformed(ActionEvent event) {
       // process Text Fields: number1 and number2 as well as Add Button events
       if (event.getSource() == number1TextField)
           number1 = Integer.parseInt(event.getActionCommand());
       else if (event.getSource() == number2TextField)
           number2 = Integer.parseInt(event.getActionCommand());
       else if (event.getSource() == addButton){
               sum = number1 + number2;
               output = "" + sum;
               System.out.println("The Result of adding number1: " + number1 +
               " and number2: " + number2 + " is: " + sum);
       else if (event.getSource() == subButton){
               sub = number1 - number2;
               output = "" + sub;
               System.out.println("The Result of subtraction number1: " + number1 +
               " and number2: " + number2 + " is: " + sub);
       // process Exit Button event
       else if (event.getSource() == exitButton) System.exit(0);
// Display Information
       displayAddition();
     } // end method actionPerformed
   }// end inner class ActionEventHandler
}  // end Class GUIAddition