1 /* 2 * Copyright (c) 1997, 2015, 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="https://docs.oracle.com/javase/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™ 63 * has been added to the <code>java.beans</code> package. 64 * Please see {@link java.beans.XMLEncoder}. 65 * 66 * @author Jeff Dinkins 67 * @since 1.2 68 */ 69 @SuppressWarnings("serial") 70 public class ButtonGroup implements Serializable { 71 72 /** 73 * The list of buttons participating in this group. 74 */ 75 protected Vector<AbstractButton> buttons = new Vector<AbstractButton>(); 76 77 /** 78 * The current selection. 79 */ 80 ButtonModel selection = null; 81 82 /** 83 * Creates a new <code>ButtonGroup</code>. 84 */ 85 public ButtonGroup() {} 86 87 /** 88 * Adds the button to the group. 89 * @param b the button to be added 90 */ 91 public void add(AbstractButton b) { 92 if(b == null) { 93 return; 94 } 95 buttons.addElement(b); 96 97 if (b.isSelected()) { 98 if (selection == null) { 99 selection = b.getModel(); 100 } else { 101 b.setSelected(false); 102 } 103 } 104 105 b.getModel().setGroup(this); 106 } 107 108 /** 109 * Removes the button from the group. 110 * @param b the button to be removed 111 */ 112 public void remove(AbstractButton b) { 113 if(b == null) { 114 return; 115 } 116 buttons.removeElement(b); 117 if(b.getModel() == selection) { 118 selection = null; 119 } 120 b.getModel().setGroup(null); 121 } 122 123 /** 124 * Clears the selection such that none of the buttons 125 * in the <code>ButtonGroup</code> are selected. 126 * 127 * @since 1.6 128 */ 129 public void clearSelection() { 130 if (selection != null) { 131 ButtonModel oldSelection = selection; 132 selection = null; 133 oldSelection.setSelected(false); 134 } 135 } 136 137 /** 138 * Returns all the buttons that are participating in 139 * this group. 140 * @return an <code>Enumeration</code> of the buttons in this group 141 */ 142 public Enumeration<AbstractButton> getElements() { 143 return buttons.elements(); 144 } 145 146 /** 147 * Returns the model of the selected button. 148 * @return the selected button model 149 */ 150 public ButtonModel getSelection() { 151 return selection; 152 } 153 154 /** 155 * Sets the selected value for the <code>ButtonModel</code>. 156 * Only one button in the group may be selected at a time. 157 * @param m the <code>ButtonModel</code> 158 * @param b <code>true</code> if this button is to be 159 * selected, otherwise <code>false</code> 160 */ 161 public void setSelected(ButtonModel m, boolean b) { 162 if (b && m != null && m != selection) { 163 ButtonModel oldSelection = selection; 164 selection = m; 165 if (oldSelection != null) { 166 oldSelection.setSelected(false); 167 } 168 m.setSelected(true); 169 } 170 } 171 172 /** 173 * Returns whether a {@code ButtonModel} is selected. 174 * 175 * @param m an isntance of {@code ButtonModel} 176 * @return {@code true} if the button is selected, 177 * otherwise returns {@code false} 178 */ 179 public boolean isSelected(ButtonModel m) { 180 return (m == selection); 181 } 182 183 /** 184 * Returns the number of buttons in the group. 185 * @return the button count 186 * @since 1.3 187 */ 188 public int getButtonCount() { 189 if (buttons == null) { 190 return 0; 191 } else { 192 return buttons.size(); 193 } 194 } 195 196 }