1 /* 2 * Copyright (c) 1997, 2008, Oracle and/or its affiliates. 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * 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 @SuppressWarnings("serial") 69 public class ButtonGroup implements Serializable { 70 71 // the list of buttons participating in this group 72 protected Vector<AbstractButton> buttons = new Vector<AbstractButton>(); 73 74 /** 75 * The current selection. 76 */ 77 ButtonModel selection = null; 78 79 /** 80 * Creates a new <code>ButtonGroup</code>. 81 */ 82 public ButtonGroup() {} 83 84 /** 85 * Adds the button to the group. 86 * @param b the button to be added 87 */ 88 public void add(AbstractButton b) { 89 if(b == null) { 90 return; 91 } 92 buttons.addElement(b); 93 94 if (b.isSelected()) { 95 if (selection == null) { 96 selection = b.getModel(); 97 } else { 98 b.setSelected(false); 99 } 100 } 101 102 b.getModel().setGroup(this); 103 } 104 105 /** 106 * Removes the button from the group. 107 * @param b the button to be removed 108 */ 109 public void remove(AbstractButton b) { 110 if(b == null) { 111 return; 112 } 113 buttons.removeElement(b); 114 if(b.getModel() == selection) { 115 selection = null; 116 } 117 b.getModel().setGroup(null); 118 } 119 120 /** 121 * Clears the selection such that none of the buttons 122 * in the <code>ButtonGroup</code> are selected. 123 * 124 * @since 1.6 125 */ 126 public void clearSelection() { 127 if (selection != null) { 128 ButtonModel oldSelection = selection; 129 selection = null; 130 oldSelection.setSelected(false); 131 } 132 } 133 134 /** 135 * Returns all the buttons that are participating in 136 * this group. 137 * @return an <code>Enumeration</code> of the buttons in this group 138 */ 139 public Enumeration<AbstractButton> getElements() { 140 return buttons.elements(); 141 } 142 143 /** 144 * Returns the model of the selected button. 145 * @return the selected button model 146 */ 147 public ButtonModel getSelection() { 148 return selection; 149 } 150 151 /** 152 * Sets the selected value for the <code>ButtonModel</code>. 153 * Only one button in the group may be selected at a time. 154 * @param m the <code>ButtonModel</code> 155 * @param b <code>true</code> if this button is to be 156 * selected, otherwise <code>false</code> 157 */ 158 public void setSelected(ButtonModel m, boolean b) { 159 if (b && m != null && m != selection) { 160 ButtonModel oldSelection = selection; 161 selection = m; 162 if (oldSelection != null) { 163 oldSelection.setSelected(false); 164 } 165 m.setSelected(true); 166 } 167 } 168 169 /** 170 * Returns whether a <code>ButtonModel</code> is selected. 171 * @return <code>true</code> if the button is selected, 172 * otherwise returns <code>false</code> 173 */ 174 public boolean isSelected(ButtonModel m) { 175 return (m == selection); 176 } 177 178 /** 179 * Returns the number of buttons in the group. 180 * @return the button count 181 * @since 1.3 182 */ 183 public int getButtonCount() { 184 if (buttons == null) { 185 return 0; 186 } else { 187 return buttons.size(); 188 } 189 } 190 191 }