javax.swing

Class ButtonGroup

public class ButtonGroup extends Object implements Serializable

Logically groups a set of buttons, so that only one of the buttons in a ButtonGroup can be selected at the same time. If one button in a ButtonGroup is selected, all other buttons are automatically deselected. While ButtonGroup can be used for all buttons that are derived from {@link AbstractButton}, it is normally only used for {@link JRadioButton}s, {@link JRadioButtonMenuItem}s and {@link JToggleButton}s. You could use it for {@link JCheckBox}es, but for the sake of usability this is strongly discouraged because the common expectation of checkboxes is that the user is allowed to make multiple selections. It makes no sense to put {@link JButton}s or {@link JMenuItem}s in a ButtonGroup because they don't implement the selected semantics.
Field Summary
protected Vector<AbstractButton>buttons
Stores references to the buttons added to this button group.
Constructor Summary
ButtonGroup()
Creates a new button group.
Method Summary
voidadd(AbstractButton b)
Adds a button to this group.
intgetButtonCount()
Return the number of buttons in this button group.
Enumeration<AbstractButton>getElements()
Returns the currently added buttons.
ButtonModelgetSelection()
Returns the currently selected button model.
booleanisSelected(ButtonModel m)
Checks if the given ButtonModel is selected in this button group.
voidremove(AbstractButton b)
Removes the specified button from this group.
voidsetSelected(ButtonModel m, boolean b)
Sets the currently selected button model.

Field Detail

buttons

protected Vector<AbstractButton> buttons
Stores references to the buttons added to this button group.

Constructor Detail

ButtonGroup

public ButtonGroup()
Creates a new button group.

Method Detail

add

public void add(AbstractButton b)
Adds a button to this group. If the button is in the selected state, then:

Parameters: b the button to add (null is ignored).

getButtonCount

public int getButtonCount()
Return the number of buttons in this button group.

Returns: the number of buttons

Since: 1.3

getElements

public Enumeration<AbstractButton> getElements()
Returns the currently added buttons.

Returns: Enumeration over all added buttons

getSelection

public ButtonModel getSelection()
Returns the currently selected button model.

Returns: the currently selected button model, null if none was selected yet

isSelected

public boolean isSelected(ButtonModel m)
Checks if the given ButtonModel is selected in this button group.

Parameters: m the button model (null permitted).

Returns: true if m is the selected button model in this group, and false otherwise.

remove

public void remove(AbstractButton b)
Removes the specified button from this group. If the button is the selected button, the current selection is set to null. The group for the removed button's model is set to null.

Parameters: b the button to remove (null is ignored).

setSelected

public void setSelected(ButtonModel m, boolean b)
Sets the currently selected button model. Only one button of a group can be selected at a time.

Parameters: m the model to select b true if this button is to be selected, false otherwise