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 * @param a an {@code Action}
123 * @since 1.3
124 */
125 public JRadioButton(Action a) {
126 this();
127 setAction(a);
128 }
129
130 /**
131 * Creates a radio button with the specified image
132 * and selection state, but no text.
133 *
134 * @param icon the image that the button should display
135 * @param selected if true, the button is initially selected;
136 * otherwise, the button is initially unselected
137 */
138 public JRadioButton(Icon icon, boolean selected) {
139 this(null, icon, selected);
140 }
141
142 /**
143 * Creates an unselected radio button with the specified text.
144 *
145 * @param text the string displayed on the radio button
146 */
147 public JRadioButton (String text) {
148 this(text, null, false);
149 }
150
151 /**
152 * Creates a radio button with the specified text
153 * and selection state.
154 *
155 * @param text the string displayed on the radio button
156 * @param selected if true, the button is initially selected;
157 * otherwise, the button is initially unselected
158 */
159 public JRadioButton (String text, boolean selected) {
160 this(text, null, selected);
161 }
162
163 /**
164 * Creates a radio button that has the specified text and image,
165 * and that is initially unselected.
166 *
167 * @param text the string displayed on the radio button
168 * @param icon the image that the button should display
169 */
170 public JRadioButton(String text, Icon icon) {
171 this(text, icon, false);
172 }
173
174 /**
175 * Creates a radio button that has the specified text, image,
176 * and selection state.
177 *
178 * @param text the string displayed on the radio button
179 * @param icon the image that the button should display
180 * @param selected if {@code true}, the button is initially selected
181 * otherwise, the button is initially unselected
182 */
183 public JRadioButton (String text, Icon icon, boolean selected) {
184 super(text, icon, selected);
185 setBorderPainted(false);
186 setHorizontalAlignment(LEADING);
187 }
188
189
190 /**
191 * Resets the UI property to a value from the current look and feel.
192 *
193 * @see JComponent#updateUI
194 */
195 public void updateUI() {
196 setUI((ButtonUI)UIManager.getUI(this));
197 }
198
199
200 /**
201 * Returns the name of the L&F class
202 * that renders this component.
203 *
204 * @return String "RadioButtonUI"
205 * @see JComponent#getUIClassID
206 * @see UIDefaults#getUI
207 * @beaninfo
208 * expert: true
209 * description: A string that specifies the name of the L&F class.
210 */
211 public String getUIClassID() {
212 return uiClassID;
213 }
214
215
216 /**
217 * The icon for radio buttons comes from the look and feel,
218 * not the Action.
219 */
220 void setIconFromAction(Action a) {
221 }
222
223 /**
224 * See readObject() and writeObject() in JComponent for more
225 * information about serialization in Swing.
226 */
227 private void writeObject(ObjectOutputStream s) throws IOException {
228 s.defaultWriteObject();
229 if (getUIClassID().equals(uiClassID)) {
230 byte count = JComponent.getWriteObjCounter(this);
231 JComponent.setWriteObjCounter(this, --count);
232 if (count == 0 && ui != null) {
233 ui.installUI(this);
234 }
235 }
236 }
237
238
239 /**
240 * Returns a string representation of this JRadioButton. This method
241 * is intended to be used only for debugging purposes, and the
242 * content and format of the returned string may vary between
243 * implementations. The returned string may be empty but may not
244 * be <code>null</code>.
245 *
246 * @return a string representation of this JRadioButton.
247 */
248 protected String paramString() {
249 return super.paramString();
250 }
251
252
253 /////////////////
254 // Accessibility support
255 ////////////////
256
257
258 /**
259 * Gets the AccessibleContext associated with this JRadioButton.
260 * For JRadioButtons, the AccessibleContext takes the form of an
261 * AccessibleJRadioButton.
262 * A new AccessibleJRadioButton instance is created if necessary.
263 *
264 * @return an AccessibleJRadioButton that serves as the
265 * AccessibleContext of this JRadioButton
266 * @beaninfo
267 * expert: true
268 * description: The AccessibleContext associated with this Button
269 */
270 public AccessibleContext getAccessibleContext() {
271 if (accessibleContext == null) {
272 accessibleContext = new AccessibleJRadioButton();
273 }
274 return accessibleContext;
275 }
276
277 /**
278 * This class implements accessibility support for the
279 * <code>JRadioButton</code> class. It provides an implementation of the
280 * Java Accessibility API appropriate to radio button
281 * user-interface elements.
282 * <p>
283 * <strong>Warning:</strong>
284 * Serialized objects of this class will not be compatible with
285 * future Swing releases. The current serialization support is
286 * appropriate for short term storage or RMI between applications running
287 * the same version of Swing. As of 1.4, support for long term storage
288 * of all JavaBeans™
289 * has been added to the <code>java.beans</code> package.
290 * Please see {@link java.beans.XMLEncoder}.
291 */
292 @SuppressWarnings("serial") // Same-version serialization only
293 protected class AccessibleJRadioButton extends AccessibleJToggleButton {
294
295 /**
296 * Get the role of this object.
297 *
298 * @return an instance of AccessibleRole describing the role of the object
299 * @see AccessibleRole
300 */
301 public AccessibleRole getAccessibleRole() {
302 return AccessibleRole.RADIO_BUTTON;
303 }
304
305 } // inner class AccessibleJRadioButton
306 }