Trail: Creating a GUI With JFC/Swing
Lesson: Using Swing Components
Section: How to Use Various Components
How to Use the ButtonGroup Component
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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 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.

Problems with the examples? Try Compiling and Running the Examples: FAQs.
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