/*
* Copyright (c) 1997, 2005, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
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 <code>ButtonGroup</code> object means that
* turning "on" one of those buttons
* turns off all other buttons in the group.
* <p>
* A <code>ButtonGroup</code> can be used with
* any set of objects that inherit from <code>AbstractButton</code>.
* Typically a button group contains instances of
* <code>JRadioButton</code>,
* <code>JRadioButtonMenuItem</code>,
* or <code>JToggleButton</code>.
* It wouldn't make sense to put an instance of
* <code>JButton</code> or <code>JMenuItem</code>
* in a button group
* because <code>JButton</code> and <code>JMenuItem</code>
* don't implement the selected state.
* <p>
* Initially, all buttons in the group are unselected.
* <p>
* For examples and further information on using button groups see
* <a href="http://java.sun.com/docs/books/tutorial/uiswing/components/button.html#radiobutton">How to Use Radio Buttons</a>,
* a section in <em>The Java Tutorial</em>.
* <p>
* <strong>Warning:</strong>
* 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 JavaBeans<sup><font size="-2">TM</font></sup>
* has been added to the <code>java.beans</code> package.
* Please see {@link java.beans.XMLEncoder}.
*
* @author Jeff Dinkins
*/
public class ButtonGroup implements Serializable {
// the list of buttons participating in this group
protected Vector<AbstractButton> buttons = new Vector();
/**
* The current selection.
*/
ButtonModel selection = null;
/**
* Creates a new <code>ButtonGroup</code>.
*/
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);
}
/**
* Clears the selection such that none of the buttons
* in the <code>ButtonGroup</code> are selected.
*
* @since 1.6
*/
public void clearSelection() {
if (selection != null) {
ButtonModel oldSelection = selection;
selection = null;
oldSelection.setSelected(false);
}
}
/**
* Returns all the buttons that are participating in
* this group.
* @return an <code>Enumeration</code> of the buttons in this group
*/
public Enumeration<AbstractButton> getElements() {
return buttons.elements();
}
/**
* Returns the model of the selected button.
* @return the selected button model
*/
public ButtonModel getSelection() {
return selection;
}
/**
* Sets the selected value for the <code>ButtonModel</code>.
* Only one button in the group may be selected at a time.
* @param m the <code>ButtonModel</code>
* @param b <code>true</code> if this button is to be
* selected, otherwise <code>false</code>
*/
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 <code>ButtonModel</code> is selected.
* @return <code>true</code> if the button is selected,
* otherwise returns <code>false</code>
*/
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();
}
}
}