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

public class ButtonGroupTest extends JFrame {
    public ButtonGroupTest() {
        super("ButtonGroupTest");
        Container cp = getContentPane();
        cp.setLayout(new FlowLayout());

        ButtonGroup group = new ButtonGroup();
        JPanel panel = new JPanel();
        panel.setBorder(new TitledBorder("3 x JRadioButton"));

        JRadioButton button1 = new JRadioButton("Tripp");
        group.add(button1);
        panel.add(button1);

        JRadioButton button2 = new JRadioButton("Trapp");
        group.add(button2);
        panel.add(button2);

        JRadioButton button3 = new JRadioButton("Trull");
        group.add(button3);
        panel.add(button3);

        cp.add(panel);
    }

    public static void main(String[] args) {
        ButtonGroupTest frame = new ButtonGroupTest();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 100);
        frame.setVisible(true);
    }
} // class ButtonGroupTest