J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2005 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | package javax.swing; |
| 26 | |
| 27 | import java.awt.event.*; |
| 28 | import java.util.Vector; |
| 29 | import java.util.Enumeration; |
| 30 | import java.io.Serializable; |
| 31 | |
| 32 | /** |
| 33 | * This class is used to create a multiple-exclusion scope for |
| 34 | * a set of buttons. Creating a set of buttons with the |
| 35 | * same <code>ButtonGroup</code> object means that |
| 36 | * turning "on" one of those buttons |
| 37 | * turns off all other buttons in the group. |
| 38 | * <p> |
| 39 | * A <code>ButtonGroup</code> can be used with |
| 40 | * any set of objects that inherit from <code>AbstractButton</code>. |
| 41 | * Typically a button group contains instances of |
| 42 | * <code>JRadioButton</code>, |
| 43 | * <code>JRadioButtonMenuItem</code>, |
| 44 | * or <code>JToggleButton</code>. |
| 45 | * It wouldn't make sense to put an instance of |
| 46 | * <code>JButton</code> or <code>JMenuItem</code> |
| 47 | * in a button group |
| 48 | * because <code>JButton</code> and <code>JMenuItem</code> |
| 49 | * don't implement the selected state. |
| 50 | * <p> |
| 51 | * Initially, all buttons in the group are unselected. |
| 52 | * <p> |
| 53 | * For examples and further information on using button groups see |
| 54 | * <a href="http://java.sun.com/docs/books/tutorial/uiswing/components/button.html#radiobutton">How to Use Radio Buttons</a>, |
| 55 | * a section in <em>The Java Tutorial</em>. |
| 56 | * <p> |
| 57 | * <strong>Warning:</strong> |
| 58 | * Serialized objects of this class will not be compatible with |
| 59 | * future Swing releases. The current serialization support is |
| 60 | * appropriate for short term storage or RMI between applications running |
| 61 | * the same version of Swing. As of 1.4, support for long term storage |
| 62 | * of all JavaBeans<sup><font size="-2">TM</font></sup> |
| 63 | * has been added to the <code>java.beans</code> package. |
| 64 | * Please see {@link java.beans.XMLEncoder}. |
| 65 | * |
| 66 | * @author Jeff Dinkins |
| 67 | */ |
| 68 | public class ButtonGroup implements Serializable { |
| 69 | |
| 70 | // the list of buttons participating in this group |
| 71 | protected Vector<AbstractButton> buttons = new Vector(); |
| 72 | |
| 73 | /** |
| 74 | * The current selection. |
| 75 | */ |
| 76 | ButtonModel selection = null; |
| 77 | |
| 78 | /** |
| 79 | * Creates a new <code>ButtonGroup</code>. |
| 80 | */ |
| 81 | public ButtonGroup() {} |
| 82 | |
| 83 | /** |
| 84 | * Adds the button to the group. |
| 85 | * @param b the button to be added |
| 86 | */ |
| 87 | public void add(AbstractButton b) { |
| 88 | if(b == null) { |
| 89 | return; |
| 90 | } |
| 91 | buttons.addElement(b); |
| 92 | |
| 93 | if (b.isSelected()) { |
| 94 | if (selection == null) { |
| 95 | selection = b.getModel(); |
| 96 | } else { |
| 97 | b.setSelected(false); |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | b.getModel().setGroup(this); |
| 102 | } |
| 103 | |
| 104 | /** |
| 105 | * Removes the button from the group. |
| 106 | * @param b the button to be removed |
| 107 | */ |
| 108 | public void remove(AbstractButton b) { |
| 109 | if(b == null) { |
| 110 | return; |
| 111 | } |
| 112 | buttons.removeElement(b); |
| 113 | if(b.getModel() == selection) { |
| 114 | selection = null; |
| 115 | } |
| 116 | b.getModel().setGroup(null); |
| 117 | } |
| 118 | |
| 119 | /** |
| 120 | * Clears the selection such that none of the buttons |
| 121 | * in the <code>ButtonGroup</code> are selected. |
| 122 | * |
| 123 | * @since 1.6 |
| 124 | */ |
| 125 | public void clearSelection() { |
| 126 | if (selection != null) { |
| 127 | ButtonModel oldSelection = selection; |
| 128 | selection = null; |
| 129 | oldSelection.setSelected(false); |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | /** |
| 134 | * Returns all the buttons that are participating in |
| 135 | * this group. |
| 136 | * @return an <code>Enumeration</code> of the buttons in this group |
| 137 | */ |
| 138 | public Enumeration<AbstractButton> getElements() { |
| 139 | return buttons.elements(); |
| 140 | } |
| 141 | |
| 142 | /** |
| 143 | * Returns the model of the selected button. |
| 144 | * @return the selected button model |
| 145 | */ |
| 146 | public ButtonModel getSelection() { |
| 147 | return selection; |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * Sets the selected value for the <code>ButtonModel</code>. |
| 152 | * Only one button in the group may be selected at a time. |
| 153 | * @param m the <code>ButtonModel</code> |
| 154 | * @param b <code>true</code> if this button is to be |
| 155 | * selected, otherwise <code>false</code> |
| 156 | */ |
| 157 | public void setSelected(ButtonModel m, boolean b) { |
| 158 | if (b && m != null && m != selection) { |
| 159 | ButtonModel oldSelection = selection; |
| 160 | selection = m; |
| 161 | if (oldSelection != null) { |
| 162 | oldSelection.setSelected(false); |
| 163 | } |
| 164 | m.setSelected(true); |
| 165 | } |
| 166 | } |
| 167 | |
| 168 | /** |
| 169 | * Returns whether a <code>ButtonModel</code> is selected. |
| 170 | * @return <code>true</code> if the button is selected, |
| 171 | * otherwise returns <code>false</code> |
| 172 | */ |
| 173 | public boolean isSelected(ButtonModel m) { |
| 174 | return (m == selection); |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * Returns the number of buttons in the group. |
| 179 | * @return the button count |
| 180 | * @since 1.3 |
| 181 | */ |
| 182 | public int getButtonCount() { |
| 183 | if (buttons == null) { |
| 184 | return 0; |
| 185 | } else { |
| 186 | return buttons.size(); |
| 187 | } |
| 188 | } |
| 189 | |
| 190 | } |