How to Use the ButtonGroup Component

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 . It shows how to use a ButtonGroup component to group a set of RadioButtons set into a JPanel.

The ButtonGroup API

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