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java.lang.Object | +--javax.swing.ButtonGroup
This class is used to create a multiple-exclusion scope for
a set of buttons. Creating a set of buttons with the
same ButtonGroup
object means that
turning "on" one of those buttons
turns off all other buttons in the group.
A ButtonGroup
can be used with
any set of objects that inherit from AbstractButton
.
Typically a button group contains instances of
JRadioButton
,
JRadioButtonMenuItem
,
or JToggleButton
.
It wouldn't make sense to put an instance of
JButton
or JMenuItem
in a button group
because JButton
and JMenuItem
don't implement the selected state.
Initially, all buttons in the group are unselected. Once any button is selected, one button is always selected in the group. There is no way to turn a button programmatically to "off", in order to clear the button group. To give the appearance of "none selected", add an invisible radio button to the group and then programmatically select that button to turn off all the displayed radio buttons. For example, a normal button with the label "none" could be wired to select the invisible radio button.
For examples and further information on using button groups see How to Use Radio Buttons, a section in The Java Tutorial.
Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing. As of 1.4, support for long term storage
of all JavaBeansTM
has been added to the java.beans
package.
Please see XMLEncoder
.
Field Summary | |
protected Vector |
buttons
|
Constructor Summary | |
ButtonGroup()
Creates a new ButtonGroup . |
Method Summary | |
void |
add(AbstractButton b)
Adds the button to the group. |
int |
getButtonCount()
Returns the number of buttons in the group. |
Enumeration |
getElements()
Returns all the buttons that are participating in this group. |
ButtonModel |
getSelection()
Returns the model of the selected button. |
boolean |
isSelected(ButtonModel m)
Returns whether a ButtonModel is selected. |
void |
remove(AbstractButton b)
Removes the button from the group. |
void |
setSelected(ButtonModel m,
boolean b)
Sets the selected value for the ButtonModel . |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
protected Vector buttons
Constructor Detail |
public ButtonGroup()
ButtonGroup
.
Method Detail |
public void add(AbstractButton b)
b
- the button to be addedpublic void remove(AbstractButton b)
b
- the button to be removedpublic Enumeration getElements()
Enumeration
of the buttons in this grouppublic ButtonModel getSelection()
public void setSelected(ButtonModel m, boolean b)
ButtonModel
.
Only one button in the group may be selected at a time.
public boolean isSelected(ButtonModel m)
ButtonModel
is selected.
true
if the button is selected,
otherwise returns false
public int getButtonCount()
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JavaTM 2 Platform Std. Ed. v1.4.0 |
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