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

class TerminationListener implements WindowListener {
    public void windowActivated(WindowEvent e) {}
    public void windowClosed(WindowEvent e) {}
    public void windowClosing(WindowEvent e) {
        System.exit(0) ;
    }
    public void windowDeactivated(WindowEvent e) {}
    public void windowDeiconified(WindowEvent e) {}
    public void windowIconified(WindowEvent e) {}
    public void windowOpened(WindowEvent e) {}
}

class RadioButtonPanel extends JPanel implements ActionListener {
    public RadioButtonPanel() {
        redButton = new JRadioButton("Red", true) ;
        blueButton = new JRadioButton("Blue", false) ;
        greenButton = new JRadioButton("Green", false) ;

        add(redButton) ;
        add(blueButton) ;
        add(greenButton) ;

        redButton.addActionListener(this) ;
        blueButton.addActionListener(this) ;
        greenButton.addActionListener(this) ;

        ButtonGroup group = new ButtonGroup() ;
        group.add(redButton) ; 
        group.add(blueButton) ; 
        group.add(greenButton) ;

        setBackground(Color.red) ;
    }

    public void actionPerformed(ActionEvent evt) {
        if(redButton.isSelected())
            setBackground(Color.red) ;
        else if(blueButton.isSelected())
            setBackground(Color.blue) ;
        else if(greenButton.isSelected())
            setBackground(Color.green) ;

        repaint() ;
    }

    private JRadioButton redButton ;
    private JRadioButton blueButton ;
    private JRadioButton greenButton ;
}

public class RadioButtonTest {
    public static void main(String [] args) {
        
        JFrame frame = new JFrame() ;

        frame.setTitle("RadioButtonTest") ;
        frame.setSize(450, 300) ;

        frame.addWindowListener(new TerminationListener()) ;

        frame.getContentPane().add(new RadioButtonPanel()) ;

        frame.setVisible(true) ;
    }
}