Use ButtonGroup to group buttons in Java

/*  w w  w. j ava2 s  .c  om*/
import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.AbstractButton;
import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.JCheckBox;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.JToggleButton;
import javax.swing.border.Border;

public class Main {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Button Group");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel(new GridLayout(0, 1));
    Border border = BorderFactory.createTitledBorder("Examples");
    panel.setBorder(border);
    ButtonGroup group = new ButtonGroup();
    AbstractButton abstract1 = new JToggleButton("Toggle Button");
    panel.add(abstract1);
    group.add(abstract1);
    AbstractButton abstract2 = new JRadioButton("Radio Button");
    panel.add(abstract2);
    group.add(abstract2);
    AbstractButton abstract3 = new JCheckBox("Check Box");
    panel.add(abstract3);
    group.add(abstract3);
    AbstractButton abstract4 = new JRadioButtonMenuItem("Radio Button Menu Item");
    panel.add(abstract4);
    group.add(abstract4);
    AbstractButton abstract5 = new JCheckBoxMenuItem("Check Box Menu Item");
    panel.add(abstract5);
    group.add(abstract5);
    frame.add(panel, BorderLayout.CENTER);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}