A little applet that demonstrates JRadionButton with a group of radio buttons that control the background color of a label.

[code=’java’]
/*******************************************************
* MYCPLUS Sample Code – http://www.mycplus.com *
* *
* This code is made available as a service to our *
* visitors and is provided strictly for the *
* purpose of illustration. *
* *
* Please direct all inquiries to saqib at mycplus.com *
*******************************************************/

// A little applet that demonstrates JRadionButton with a group
// of radio buttons that control the background color of a label.

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

public class RadioButtonDemo extends JApplet implements ActionListener {

JRadioButton redRadio, blueRadio, greenRadio, blackRadio; // the buttons

JLabel label; // Will show the background color specified by
// the selected radio button.

public void init() {

getContentPane().setLayout( new GridLayout(5,1) );

ButtonGroup colorGroup = new ButtonGroup();
// A ButtonGroup is needed to synchronize the radio
// buttons so that no more than one of them will
// be selected at any given time. Each button will be
// added to this group.

redRadio = new JRadioButton(“Red”);
colorGroup.add(redRadio);
redRadio.addActionListener(this);
getContentPane().add(redRadio);

blueRadio = new JRadioButton(“Blue”);
colorGroup.add(blueRadio);
blueRadio.addActionListener(this);
getContentPane().add(blueRadio);

greenRadio = new JRadioButton(“Green”);
colorGroup.add(greenRadio);
greenRadio.addActionListener(this);
getContentPane().add(greenRadio);

blackRadio = new JRadioButton(“Black”);
colorGroup.add(blackRadio);
blackRadio.addActionListener(this);
getContentPane().add(blackRadio);

redRadio.setSelected(true); // Set an initial selection.

label = new JLabel(“Red is selected”, JLabel.CENTER);
label.setForeground(Color.white);
label.setBackground(Color.red);
label.setOpaque(true);
getContentPane().add(label);

} // end init()

public void actionPerformed(ActionEvent evt) {
// The applet serves as a listener for all the radio buttons,
// so this method is called whenever the user clicks on one
// of the buttons.
if ( redRadio.isSelected() ) {
label.setBackground(Color.red);
label.setText(“Red is selected”);
}
else if ( blueRadio.isSelected() ) {
label.setBackground(Color.blue);
label.setText(“Blue is selected”);
}
else if ( greenRadio.isSelected() ) {
label.setBackground(Color.green);
label.setText(“Green is selected”);
}
else if ( blackRadio.isSelected() ) {
label.setBackground(Color.black);
label.setText(“Black is selected”);
}
} // end actionPerformed()

} // end class RadioButtonDemo
[/code]

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