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JavaTM 2 Platform
Std. Ed. v1.3.1

Class ButtonGroup

All Implemented Interfaces:

public class ButtonGroup
extends Object
implements Serializable

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. A future release of Swing will provide support for long term persistence.

See Also:
Serialized Form

Field Summary
protected  Vector buttons
Constructor Summary
          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()
          Return all the buttons that are participating in this group.
 ButtonModel getSelection()
          Return the selected button model.
 boolean isSelected(ButtonModel m)
          Returns the selected value for the button.
 void remove(AbstractButton b)
          Removes the button from the group.
 void setSelected(ButtonModel m, boolean b)
          Sets the selected value for the button.
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()
Creates a new ButtonGroup.
Method Detail


public void add(AbstractButton b)
Adds the button to the group.


public void remove(AbstractButton b)
Removes the button from the group.


public Enumeration getElements()
Return all the buttons that are participating in this group.


public ButtonModel getSelection()
Return the selected button model.


public void setSelected(ButtonModel m,
                        boolean b)
Sets the selected value for the button.


public boolean isSelected(ButtonModel m)
Returns the selected value for the button.


public int getButtonCount()
Returns the number of buttons in the group.

JavaTM 2 Platform
Std. Ed. v1.3.1

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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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