Java Tips - How to implement group of buttons in an application

This Java tip illustrates a method of creating a group of buttons in an application. A ButtonGroup is usually created when developer wants to provide a list of choices to users and wants him to choose one from them. If user selects second choice his first choice will be deselected.

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;



public class SimpleButtonGroupExample {

    

    public static void main(String[] args) {

        // Some choices

        JRadioButton choice1, choice2, choice3;

        choice1 = new JRadioButton("Bach: Well Tempered Clavier, Book I");

        choice1.setActionCommand("bach1");

        choice2 = new JRadioButton("Bach: Well Tempered Clavier, Book II");

        choice2.setActionCommand("bach2");

        choice3 = new JRadioButton("Shostakovich: 24 Preludes and Fugues");

        choice3.setActionCommand("shostakovich");

        

        // A group, to ensure that we only vote for one.

        final ButtonGroup group = new ButtonGroup();

        group.add(choice1);

        group.add(choice2);

        group.add(choice3);

        

        // A simple ActionListener, showing each selection 

        // using the ButtonModel

        class VoteActionListener implements ActionListener {

            public void actionPerformed(ActionEvent ev) {

                String choice = group.getSelection().getActionCommand();

                System.out.println("ACTION Choice Selected: " + choice);

            }

        }

        

        // A simple ItemListener, showing each selection and deselection

        class VoteItemListener implements ItemListener {

            public void itemStateChanged(ItemEvent ev) {

                boolean selected = (ev.getStateChange() == 

                        ItemEvent.SELECTED);

                

                AbstractButton button = 

                        (AbstractButton)ev.getItemSelectable();

                

                System.out.println("ITEM Choice Selected: " + selected +

                        ", Selection: " + button.getActionCommand());

            }

        }

        

        // Add listeners to each button

        ActionListener alisten = new VoteActionListener();

        choice1.addActionListener(alisten);

        choice2.addActionListener(alisten);

        choice3.addActionListener(alisten);

        

        ItemListener ilisten = new VoteItemListener();

        choice1.addItemListener(ilisten);

        choice2.addItemListener(ilisten);

        choice3.addItemListener(ilisten);

        

        // Throw everything together

        JFrame frame = new JFrame();

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Container c = frame.getContentPane();

        c.setLayout(new GridLayout(0, 1));

        c.add(new JLabel("Vote for your favorite prelude & fugue cycle"));

        c.add(choice1);

        c.add(choice2);

        c.add(choice3);

        frame.pack();

        frame.setVisible(true);

    }

}
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