This section provides a tutorial example on how to use the javax.swing.JRadioButtonMenuItem class to create multiple radio button menu items and added them into a button group. If one radio button menu item is selected in a group, all others will be unselected.
Other the regular menu item class, javax.swing.JMenuItem, Swing supports a special menu item class,
javax.swing.JRadioButtonMenuItem, which represents radio button menu items with following special features:
A radio button menu item will be listed with a radio button icon.
The radio button icon will be displayed as checked if the radio button menu item is selected.
The radio button icon will be displayed as unchecked if the radio button menu item is unselected.
Multple radio button menu items are added into a ButtonGroup object to form button group.
If one radio button menu item in a button group is selected, all other radio button menu items will be unselected.
Here is an example program I wrote to test the JRadioButtonMenuItem classes:
/**
* JRadioButtonMenuItemTest.java
* Copyright (c) 2009 by Dr. Herong Yang, http://www.herongyang.com/
*/
import javax.swing.*;
public class JRadioButtonMenuItemTest {
JFrame myFrame = null;
public static void main(String[] a) {
(new JRadioButtonMenuItemTest()).test();
}
private void test() {
myFrame = new JFrame("Radio Button Menu Item Test");
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myFrame.setBounds(50,50,250,150);
myFrame.setContentPane(new JDesktopPane());
JMenuBar myMenuBar = new JMenuBar();
JMenu myMenu = getFileMenu();
myMenuBar.add(myMenu);
myMenu = getColorMenu();
myMenuBar.add(myMenu);
myMenu = getOptionMenu();
myMenuBar.add(myMenu);
JMenuItem myItem = new JMenuItem("Help");
myMenuBar.add(myItem);
myFrame.setJMenuBar(myMenuBar);
myFrame.setVisible(true);
}
private JMenu getFileMenu() {
JMenu myMenu = new JMenu("File");
JMenuItem myItem = new JMenuItem("Open");
myMenu.add(myItem);
myItem = new JMenuItem("Close");
myItem.setEnabled(false);
myMenu.add(myItem);
myMenu.addSeparator();
myItem = new JMenuItem("Exit");
myMenu.add(myItem);
return myMenu;
}
private JMenu getColorMenu() {
JMenu myMenu = new JMenu("Color");
ButtonGroup myGroup = new ButtonGroup();
JRadioButtonMenuItem myItem = new JRadioButtonMenuItem("Red");
myItem.setSelected(true);
myGroup.add(myItem);
myMenu.add(myItem);
myItem = new JRadioButtonMenuItem("Green");
myGroup.add(myItem);
myMenu.add(myItem);
myItem = new JRadioButtonMenuItem("Blue");
myGroup.add(myItem);
myMenu.add(myItem);
return myMenu;
}
private JMenu getOptionMenu() {
JMenu myMenu = new JMenu("Option");
JMenuItem myItem = new JMenuItem("Sound");
myMenu.add(myItem);
myItem = new JMenuItem("Auto save");
myMenu.add(myItem);
return myMenu;
}
}
If you run this example, you will see the frame window shows up with the menu bar like this:
Interesting notes about this tutorial example:
A radio button menu item can be listed as selected by default, if the setSelected(true) method is called on the item.
The "Red" radio button menu item selected by default in this example.
Sample programs listed in this section have been tested with JDK 1.6.0.
