Need help with ActionListener (Code posted)

[CJ78]

I'm learning Java and I am trying to get this class to work, this is only my second time using ActionListener. In this application my buttons do not work when I click them. A system exit should occur, but it doesn't...and I just can't figure out whats wrong. I'd greatly appreciate any help or insight. This code compiles correctly, but you can get the complete file here (cheesy name,eh).

http://www.geocities.com/mr_uniq1/LunchOrder.java

==========================================================


import javax.swing.*;
import java.awt.*;
import java.text.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.border.*;

public class LunchOrder extends JFrame
{
public LunchOrder()
{
setTitle("Lunch Order"
addWindowListener(
new WindowAdapter()
{
public void windowClosing(WindowEvent eex)
{
System.exit(0);
}
});

Toolkit tk = Toolkit.getDefaultToolkit();
Dimension d = tk.getScreenSize();
int width = 400;
int height = 300;
setBounds((d.width - width)/2, (d.height - height)/2, width, height);

Container contentPane = getContentPane();
LunchPanel lnPanel = new LunchPanel();
contentPane.add(lnPanel);
setResizable(false);
}

public static void main(String[] args)
{
JFrame frame = new LunchOrder();
frame.show();
}
}

class LunchPanel extends JPanel implements ActionListener
{
public JButton orderButton, exitButton;
private JRadioButton hamburgerButton, pizzaButton, saladButton;
private JCheckBox lettuceCheck, mayoCheck, mustardCheck;

public LunchPanel()
{
//panels
JPanel coursePanel = new JPanel();
JPanel addOnsPanel = new JPanel();
JPanel totalPanel = new JPanel();

//borders
Border etchedBorder = BorderFactory.createEtchedBorder();
Border courseBorder = BorderFactory.createTitledBorder(etchedBorder,"Main Course"
Border addOnsBorder = BorderFactory.createTitledBorder(etchedBorder,"Add-Ons($.25/each)"
Border totalsBorder = BorderFactory.createTitledBorder(etchedBorder,"Order Total"
coursePanel.setBorder(courseBorder);
addOnsPanel.setBorder(addOnsBorder);
totalPanel.setBorder(totalsBorder);

//radiobuttons
coursePanel.setLayout(new BorderLayout());
hamburgerButton = new JRadioButton("Hamburger - $6.95 ", true);
pizzaButton = new JRadioButton("Pizza - $5.95"
saladButton = new JRadioButton("Salad - $4.95"
pizzaButton.addActionListener(this);
saladButton.addActionListener(this);
hamburgerButton.addActionListener(this);
ButtonGroup radioGroup= new ButtonGroup();
radioGroup.add(hamburgerButton);
radioGroup.add(pizzaButton);
radioGroup.add(saladButton);
coursePanel.add(hamburgerButton, BorderLayout.NORTH);
coursePanel.add(pizzaButton, BorderLayout.CENTER);
coursePanel.add(saladButton, BorderLayout.SOUTH);

//buttons
JButton orderButton = new JButton("Place Order"
JButton exitButton = new JButton("Exit"
orderButton.addActionListener(this);
exitButton.addActionListener(this);

//checks
addOnsPanel.setLayout(new BorderLayout());
lettuceCheck = new JCheckBox("Lettuce, tomato, and onions"
mayoCheck = new JCheckBox("Mayonnaise"
mustardCheck = new JCheckBox("Mustard"
addOnsPanel.add(lettuceCheck, BorderLayout.NORTH);
addOnsPanel.add(mayoCheck, BorderLayout.CENTER);
addOnsPanel.add(mustardCheck, BorderLayout.SOUTH);

//textfields
totalPanel.setLayout(new BorderLayout());
JLabel subtLabel = new JLabel("SubTotal:"
JLabel taxLabel = new JLabel("Tax(7.85%)"
JLabel totalLabel = new JLabel("Total due:"
JTextField subtText = new JTextField(7);
JTextField taxText = new JTextField(7);
JTextField totalText = new JTextField(7);
JPanel subtPanel = new JPanel();
JPanel taxPanel = new JPanel();
JPanel totPanel = new JPanel();
subtPanel.add(subtLabel, BorderLayout.WEST);
taxPanel.add(taxLabel, BorderLayout.WEST);
totPanel.add(totalLabel, BorderLayout.WEST);
subtPanel.add(subtText, BorderLayout.EAST);
taxPanel.add(taxText, BorderLayout.EAST);
totPanel.add(totalText, BorderLayout.EAST);
totalPanel.add(subtPanel, BorderLayout.NORTH);
totalPanel.add(taxPanel, BorderLayout.CENTER);
totalPanel.add(totPanel, BorderLayout.SOUTH);

setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
c.weightx = 100;
c.weighty = 100;
c.ipadx = 5;

//c.anchor = GridBagConstraints.WEST;
c = getConstraints(c, 1, 1, 1, 2);
add(coursePanel, c);

//c.anchor = GridBagConstraints.EAST;
c = getConstraints(c, 3, 1, 2, 2);
add(addOnsPanel, c);

//c.anchor = GridBagConstraints.WEST;
c = getConstraints(c, 1, 3, 2, 2);
add(totalPanel, c);

//c.anchor = GridBagConstraints.EAST;
c = getConstraints(c, 3, 3, 1, 1);
add(orderButton, c);
c = getConstraints(c, 3, 4, 1, 1);
add(exitButton, c);
}


private GridBagConstraints getConstraints(GridBagConstraints c, int x, int y, int width, int height)
{
c.gridx = x;
c.gridy = y;
c.gridwidth = width;
c.gridheight = height;
return c;
}

public void actionPerformed(ActionEvent e)
{
//try
//{
Object source = e.getSource();

if (source == exitButton)
System.exit(0);

if (source == orderButton)
{
System.exit(0);
}
// }
// catch(NullPointerException exc)
// {
// JOptionPane.showMessageDialog(this,"Invalid data entered. \nPlease check all numbers and try again"
// }
//
// catch (NumberFormatException nfe)
// {
// JOptionPane.showMessageDialog(this,"Invalid data entered. \nPlease check all numbers and try again"
// }

}
}

 

[FredrikN]

Hello
The problem is that method actionPerformed does not have access to your button.
You are creating the two buttons inside the LunchPanel constructor.

If you create them in the LunchOrder order class it will work just fine.



public void actionPerformed(ActionEvent e)
{
//try
//{
Object source = e.getSource();

if (source == exitButton)
System.exit(0);


exitButton will always be null here, so source==exitButton will never be true.

You can change the

//buttons
JButton orderButton = new JButton("Place Order"
JButton exitButton = new JButton("Exit"

to

//buttons
orderButton = new JButton("Place Order"
exitButton = new JButton("Exit"

and then make a deklaration above the lunch order constructor like

public class LunchOrder extends JFrame
{
private JButton exitButton;
private JButton orderButton;