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.

Subclass JFrame

Call ContextPane together with a layout manager

Declare and configure a set of radio buttons or toggle buttons

Instantiate a ButtonGroup object

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

目的

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. 例如：

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.

例子

Where Described

Notes

RadioButtonDemo

How to Use Radio Buttons

Uses radio buttons to determine which of five images it should display.