/*
* @(#)ButtonGroup.java 1.37 04/05/05
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.swing;
import java.awt.event.*;
import java.util.Vector;
import java.util.Enumeration;
import java.io.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. As of 1.4, support for long term storage
* of all JavaBeansTM
* has been added to the java.beans
package.
* Please see {@link java.beans.XMLEncoder}.
*
* @version 1.37 05/05/04
* @author Jeff Dinkins
*/
public class ButtonGroup implements Serializable {
// the list of buttons participating in this group
protected VectorButtonGroup
.
*/
public ButtonGroup() {}
/**
* Adds the button to the group.
* @param b the button to be added
*/
public void add(AbstractButton b) {
if(b == null) {
return;
}
buttons.addElement(b);
if (b.isSelected()) {
if (selection == null) {
selection = b.getModel();
} else {
b.setSelected(false);
}
}
b.getModel().setGroup(this);
}
/**
* Removes the button from the group.
* @param b the button to be removed
*/
public void remove(AbstractButton b) {
if(b == null) {
return;
}
buttons.removeElement(b);
if(b.getModel() == selection) {
selection = null;
}
b.getModel().setGroup(null);
}
/**
* Returns all the buttons that are participating in
* this group.
* @return an Enumeration
of the buttons in this group
*/
public EnumerationButtonModel
.
* Only one button in the group may be selected at a time.
* @param m the ButtonModel
* @param b true
if this button is to be
* selected, otherwise false
*/
public void setSelected(ButtonModel m, boolean b) {
if (b && m != null && m != selection) {
ButtonModel oldSelection = selection;
selection = m;
if (oldSelection != null) {
oldSelection.setSelected(false);
}
m.setSelected(true);
}
}
/**
* Returns whether a ButtonModel
is selected.
* @return true
if the button is selected,
* otherwise returns false
*/
public boolean isSelected(ButtonModel m) {
return (m == selection);
}
/**
* Returns the number of buttons in the group.
* @return the button count
* @since 1.3
*/
public int getButtonCount() {
if (buttons == null) {
return 0;
} else {
return buttons.size();
}
}
}