The ButtonGroup component manages the selected/unselected state for a set of buttons. For the group, the ButtonGroup instance guarantees that only one button can be selected at a time.

Initially, all buttons managed by a ButtonGroup instance are unselected.

How to Use ButtonGroup Features

You can use ButtonGroup with any set of objects that inherit from AbstractButton. Typically a button group contains instances of JRadioButton, JRadioButtonMenuItem, or JToggleButton. It would not make sense to put an instance of JButton or JMenuItem in a button group because JButton and JMenuItem do not implement the select/deselect button state.

In general, you will typically follow these steps to write code that uses a ButtonGroup component.

1. Subclass JFrame
2. Call ContextPane together with a layout manager
3. Declare and configure a set of radio buttons or toggle buttons
4. Instantiate a ButtonGroup object
5. Call the add method on that buttongroup object in order to add each button to the group.

For details and a code example, see How to Use Radio Buttons. It shows how to use a ButtonGroup component to group a set of RadioButtons set into a JPanel.

The ButtonGroup API

 

Commonly Used Button Group Constructors/Methods

Constructor or Method	Purpose
ButtonGroup()	Create a ButtonGroup instance.
void add(AbstractButton) void remove(AbstractButton)	Add a button to the group, or remove a button from the group.
public ButtonGroup getGroup() (in DefaultButtonModel)	Get the ButtonGroup, if any, that controls a button. For example: ButtonGroup group = ((DefaultButtonModel)button.getModel()).getGroup();
public ButtonGroup clearSelection()	Clears the state of selected buttons in the ButtonGroup. None of the buttons in the ButtonGroup are selected .

ButtonGroup Examples

The following demonstration application uses the ButtonGroup component to group radio buttons displaying on a Window.

Example	Where Described	Notes
RadioButtonDemo	How to Use Radio Buttons	Uses radio buttons to determine which of five images it should display.