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javax.swing

Class ButtonGroup

Implemented Interfaces:
Serializable
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 AbstractButton, it is normally only used for JRadioButtons, JRadioButtonMenuItems and JToggleButtons. You could use it for JCheckBoxes, 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 JButtons or JMenuItems in a ButtonGroup because they don't implement the selected semantics.
See Also:
Serialized Form

Field Summary

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

Constructor Summary

ButtonGroup()
Creates a new button group.

Method Summary

void
add(AbstractButton b)
Adds a button to this group.
int
getButtonCount()
Return the number of buttons in this button group.
Enumeration
getElements()
Returns the currently added buttons.
ButtonModel
getSelection()
Returns the currently selected button model.
boolean
isSelected(ButtonModel m)
Checks if the given ButtonModel is selected in this button group.
void
remove(AbstractButton b)
Removes the specified button from this group.
void
setSelected(ButtonModel m, boolean b)
Sets the currently selected button model.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

buttons

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

Constructor Details

ButtonGroup

public ButtonGroup()
Creates a new button group.

Method Details

add

public void add(AbstractButton b)
Adds a button to this group. If the button is in the selected state, then:
  • if the group has no current selection, the new button becomes the selected button for the group;
  • if the group already has a selected button, the new button is set to "not selected".
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 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
ButtonGroup.java -- Copyright (C) 2002, 2006, Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

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