Changing a JButton color...

Question

This is probably a simple question to most of you out there. I apologise in advance.
I am writing a kind of robot simulator program for a university project, at the moment all I need is for the buttons in the centre window to change colour on click and remain that colour. I cannot get it to work and was wondering if anyone had any not too complicated suggestions.
The place I have the problem is in the action performed area.
My code looks like this:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class RoboSim extends JFrame implements ActionListener
    private JButton button1, button2, button3, button4, button5, squareButton;
    private JPanel panel1;
    private JLabel squareLabel, directionLabel;
    private JTextField squareField, directionField;
    public static void main(String[] args)
        RoboSim frame = new RoboSim();
        frame.setSize(500, 450);
        frame.createGUI();
        frame.setVisible(true);
    private void createGUI()
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        Container window = getContentPane();
        window.setLayout(new BorderLayout() );
          Toolkit toolkit = Toolkit.getDefaultToolkit();
             Image icon = toolkit.getImage(getClass().getResource("icon.gif"));
             setIconImage(icon);
             //EAST PANEL START
        JPanel eastPanel = new JPanel();
        eastPanel.setPreferredSize(new Dimension(100, 500));
        eastPanel.setLayout(new FlowLayout());
       button1 = new JButton("Forward");
       eastPanel.add(button1);
       button1.addActionListener(this);
       button2 = new JButton("  Rotate ");
       eastPanel.add(button2);
       button2.addActionListener(this);
       button3 = new JButton("   Clear  ");
       eastPanel.add(button3);
       button3.addActionListener(this);
       button4 = new JButton("    Exit    ");
       eastPanel.add(button4);
       button4.addActionListener(this);
       button5 = new JButton("  About  ");
       eastPanel.add(button5);
       button5.addActionListener(this);
        eastPanel.setBackground(Color.GRAY);
        window.add(eastPanel, BorderLayout.EAST);
        //EAST PANEL END
        //SOUTH PANEL START
        JPanel southPanel = new JPanel();
        southPanel.setLayout(new FlowLayout());
       squareLabel = new JLabel("Square ");
       southPanel.add(squareLabel);
       squareField = new JTextField(3);
       southPanel.add(squareField);
       directionLabel = new JLabel("Direction ");
       southPanel.add(directionLabel);
       directionField = new JTextField(3);
       southPanel.add(directionField);
        southPanel.setBackground(Color.GRAY);
        window.add(southPanel, BorderLayout.SOUTH);
        //SOUTH PANEL END
        //CENTRE PANEL START
        JPanel centrePanel = new JPanel();
        centrePanel.setLayout(new GridLayout(10,10));
          for (int square = 0; square <= 99; square++)
               squareButton = new JButton();
               squareButton.addActionListener(this);                    
               squareButton.setBackground(Color.GREEN);
               centrePanel.add(squareButton);
        centrePanel.setBackground(Color.LIGHT_GRAY);
        window.add(centrePanel, BorderLayout.CENTER);
        //CENTRE PANEL END
    public void actionPerformed(ActionEvent event)
         Object source = event.getSource();
        if (source == squareButton)
               // I CANNOT WORK OUT WHAT TO PUT HERE
        if (source == button5)
             JOptionPane.showMessageDialog(null,"� RoboSim \n "+
             "Created By !Removed for post! \n "+
             "!Removed for post! \n "+
             "!Removed for post!");
          if (source == button4)
             System.exit(0);
        if (source == button3)
        if (source == button2)
        if (source == button1)
}

Answer 1

Im not sure I understand the last bit of help, how do
I apply the ActionListener to all 100 of the buttons?You already are "applying" the same listener to all the 100 buttons, the listener being your "RoboSim" instance.
The problem with your code (at least the problem camickr targetted) is this line:
if (source == squareButton)That's because "squareButton" will be only one of the one hundred buttons, as a matter of fact the last one created.
But, on the other hand, you have to check the source in that ActionListener because the event could also come from other sources than those one hundred buttons.
So, what camickr suggested was that you create:
- one ActionListener for the 100 buttons, and only for those, so that, when it gets invoked, you know the event comes from one of these buttons
- another ActionListener for the other events, wherein you check the source. For that you can keep the one you already have.
You can easily create EventListeners as anonymous inner classes. See examples here: http://java.sun.com/docs/books/tutorial/uiswing/events/generalrules.html#innerClasses.
For an overview, see this: http://java.sun.com/docs/books/tutorial/uiswing/events/index.html.