1 /*
2 * Copyright (c) 1997, 2014, 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.*;
28 import java.awt.event.*;
29 import java.beans.*;
30
31 import javax.swing.plaf.*;
32 import javax.accessibility.*;
33
34 import java.io.ObjectOutputStream;
35 import java.io.ObjectInputStream;
36 import java.io.IOException;
37
38
39 /**
40 * An implementation of a radio button -- an item that can be selected or
41 * deselected, and which displays its state to the user.
42 * Used with a {@link ButtonGroup} object to create a group of buttons
43 * in which only one button at a time can be selected. (Create a ButtonGroup
44 * object and use its <code>add</code> method to include the JRadioButton objects
45 * in the group.)
46 * <blockquote>
47 * <strong>Note:</strong>
48 * The ButtonGroup object is a logical grouping -- not a physical grouping.
49 * To create a button panel, you should still create a {@link JPanel} or similar
50 * container-object and add a {@link javax.swing.border.Border} to it to set it off from surrounding
51 * components.
52 * </blockquote>
53 * <p>
54 * Buttons can be configured, and to some degree controlled, by
55 * <code><a href="Action.html">Action</a></code>s. Using an
56 * <code>Action</code> with a button has many benefits beyond directly
57 * configuring a button. Refer to <a href="Action.html#buttonActions">
58 * Swing Components Supporting <code>Action</code></a> for more
59 * details, and you can find more information in <a
60 * href="http://docs.oracle.com/javase/tutorial/uiswing/misc/action.html">How
61 * to Use Actions</a>, a section in <em>The Java Tutorial</em>.
62 * <p>
63 * See <a href="http://docs.oracle.com/javase/tutorial/uiswing/components/button.html">How to Use Buttons, Check Boxes, and Radio Buttons</a>
64 * in <em>The Java Tutorial</em>
65 * for further documentation.
66 * <p>
67 * <strong>Warning:</strong> Swing is not thread safe. For more
68 * information see <a
69 * href="package-summary.html#threading">Swing's Threading
70 * Policy</a>.
71 * <p>
72 * <strong>Warning:</strong>
73 * Serialized objects of this class will not be compatible with
74 * future Swing releases. The current serialization support is
75 * appropriate for short term storage or RMI between applications running
76 * the same version of Swing. As of 1.4, support for long term storage
77 * of all JavaBeans™
78 * has been added to the <code>java.beans</code> package.
79 * Please see {@link java.beans.XMLEncoder}.
80 *
81 * @beaninfo
82 * attribute: isContainer false
83 * description: A component which can display it's state as selected or deselected.
84 *
85 * @see ButtonGroup
86 * @see JCheckBox
87 * @author Jeff Dinkins
88 * @since 1.2
89 */
90 @SuppressWarnings("serial") // Same-version serialization only
91 public class JRadioButton extends JToggleButton implements Accessible {
92
93 /**
94 * @see #getUIClassID
95 * @see #readObject
96 */
97 private static final String uiClassID = "RadioButtonUI";
98
99
100 /**
101 * Creates an initially unselected radio button
102 * with no set text.
103 */
104 public JRadioButton () {
105 this(null, null, false);
106 }
107
108 /**
109 * Creates an initially unselected radio button
110 * with the specified image but no text.
111 *
112 * @param icon the image that the button should display
113 */
114 public JRadioButton(Icon icon) {
115 this(null, icon, false);
116 }
117
118 /**
119 * Creates a radiobutton where properties are taken from the
120 * Action supplied.
121 *
122 * @since 1.3
123 */
124 public JRadioButton(Action a) {
125 this();
126 setAction(a);
127 }
128
129 /**
130 * Creates a radio button with the specified image
131 * and selection state, but no text.
132 *
133 * @param icon the image that the button should display
134 * @param selected if true, the button is initially selected;
135 * otherwise, the button is initially unselected
136 */
137 public JRadioButton(Icon icon, boolean selected) {
138 this(null, icon, selected);
139 }
140
141 /**
142 * Creates an unselected radio button with the specified text.
143 *
144 * @param text the string displayed on the radio button
145 */
146 public JRadioButton (String text) {
147 this(text, null, false);
148 }
149
150 /**
151 * Creates a radio button with the specified text
152 * and selection state.
153 *
154 * @param text the string displayed on the radio button
155 * @param selected if true, the button is initially selected;
156 * otherwise, the button is initially unselected
157 */
158 public JRadioButton (String text, boolean selected) {
159 this(text, null, selected);
160 }
161
162 /**
163 * Creates a radio button that has the specified text and image,
164 * and that is initially unselected.
165 *
166 * @param text the string displayed on the radio button
167 * @param icon the image that the button should display
168 */
169 public JRadioButton(String text, Icon icon) {
170 this(text, icon, false);
171 }
172
173 /**
174 * Creates a radio button that has the specified text, image,
175 * and selection state.
176 *
177 * @param text the string displayed on the radio button
178 * @param icon the image that the button should display
179 */
180 public JRadioButton (String text, Icon icon, boolean selected) {
181 super(text, icon, selected);
182 setBorderPainted(false);
183 setHorizontalAlignment(LEADING);
184 }
185
186
187 /**
188 * Resets the UI property to a value from the current look and feel.
189 *
190 * @see JComponent#updateUI
191 */
192 public void updateUI() {
193 setUI((ButtonUI)UIManager.getUI(this));
194 }
195
196
197 /**
198 * Returns the name of the L&F class
199 * that renders this component.
200 *
201 * @return String "RadioButtonUI"
202 * @see JComponent#getUIClassID
203 * @see UIDefaults#getUI
204 * @beaninfo
205 * expert: true
206 * description: A string that specifies the name of the L&F class.
207 */
208 public String getUIClassID() {
209 return uiClassID;
210 }
211
212
213 /**
214 * The icon for radio buttons comes from the look and feel,
215 * not the Action.
216 */
217 void setIconFromAction(Action a) {
218 }
219
220 /**
221 * See readObject() and writeObject() in JComponent for more
222 * information about serialization in Swing.
223 */
224 private void writeObject(ObjectOutputStream s) throws IOException {
225 s.defaultWriteObject();
226 if (getUIClassID().equals(uiClassID)) {
227 byte count = JComponent.getWriteObjCounter(this);
228 JComponent.setWriteObjCounter(this, --count);
229 if (count == 0 && ui != null) {
230 ui.installUI(this);
231 }
232 }
233 }
234
235
236 /**
237 * Returns a string representation of this JRadioButton. This method
238 * is intended to be used only for debugging purposes, and the
239 * content and format of the returned string may vary between
240 * implementations. The returned string may be empty but may not
241 * be <code>null</code>.
242 *
243 * @return a string representation of this JRadioButton.
244 */
245 protected String paramString() {
246 return super.paramString();
247 }
248
249
250 /////////////////
251 // Accessibility support
252 ////////////////
253
254
255 /**
256 * Gets the AccessibleContext associated with this JRadioButton.
257 * For JRadioButtons, the AccessibleContext takes the form of an
258 * AccessibleJRadioButton.
259 * A new AccessibleJRadioButton instance is created if necessary.
260 *
261 * @return an AccessibleJRadioButton that serves as the
262 * AccessibleContext of this JRadioButton
263 * @beaninfo
264 * expert: true
265 * description: The AccessibleContext associated with this Button
266 */
267 public AccessibleContext getAccessibleContext() {
268 if (accessibleContext == null) {
269 accessibleContext = new AccessibleJRadioButton();
270 }
271 return accessibleContext;
272 }
273
274 /**
275 * This class implements accessibility support for the
276 * <code>JRadioButton</code> class. It provides an implementation of the
277 * Java Accessibility API appropriate to radio button
278 * user-interface elements.
279 * <p>
280 * <strong>Warning:</strong>
281 * Serialized objects of this class will not be compatible with
282 * future Swing releases. The current serialization support is
283 * appropriate for short term storage or RMI between applications running
284 * the same version of Swing. As of 1.4, support for long term storage
285 * of all JavaBeans™
286 * has been added to the <code>java.beans</code> package.
287 * Please see {@link java.beans.XMLEncoder}.
288 */
289 @SuppressWarnings("serial") // Same-version serialization only
290 protected class AccessibleJRadioButton extends AccessibleJToggleButton {
291
292 /**
293 * Get the role of this object.
294 *
295 * @return an instance of AccessibleRole describing the role of the object
296 * @see AccessibleRole
297 */
298 public AccessibleRole getAccessibleRole() {
299 return AccessibleRole.RADIO_BUTTON;
300 }
301
302 } // inner class AccessibleJRadioButton
303 }