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 */
89 @SuppressWarnings("serial") // Same-version serialization only
90 public class JRadioButton extends JToggleButton implements Accessible {
91
92 /**
93 * @see #getUIClassID
94 * @see #readObject
95 */
96 private static final String uiClassID = "RadioButtonUI";
97
98
99 /**
100 * Creates an initially unselected radio button
101 * with no set text.
102 */
103 public JRadioButton () {
104 this(null, null, false);
105 }
106
107 /**
108 * Creates an initially unselected radio button
109 * with the specified image but no text.
110 *
111 * @param icon the image that the button should display
112 */
113 public JRadioButton(Icon icon) {
114 this(null, icon, false);
115 }
116
117 /**
118 * Creates a radiobutton where properties are taken from the
119 * Action supplied.
120 *
121 * @since 1.3
122 */
123 public JRadioButton(Action a) {
124 this();
125 setAction(a);
126 }
127
128 /**
129 * Creates a radio button with the specified image
130 * and selection state, but no text.
131 *
132 * @param icon the image that the button should display
133 * @param selected if true, the button is initially selected;
134 * otherwise, the button is initially unselected
135 */
136 public JRadioButton(Icon icon, boolean selected) {
137 this(null, icon, selected);
138 }
139
140 /**
141 * Creates an unselected radio button with the specified text.
142 *
143 * @param text the string displayed on the radio button
144 */
145 public JRadioButton (String text) {
146 this(text, null, false);
147 }
148
149 /**
150 * Creates a radio button with the specified text
151 * and selection state.
152 *
153 * @param text the string displayed on the radio button
154 * @param selected if true, the button is initially selected;
155 * otherwise, the button is initially unselected
156 */
157 public JRadioButton (String text, boolean selected) {
158 this(text, null, selected);
159 }
160
161 /**
162 * Creates a radio button that has the specified text and image,
163 * and that is initially unselected.
164 *
165 * @param text the string displayed on the radio button
166 * @param icon the image that the button should display
167 */
168 public JRadioButton(String text, Icon icon) {
169 this(text, icon, false);
170 }
171
172 /**
173 * Creates a radio button that has the specified text, image,
174 * and selection state.
175 *
176 * @param text the string displayed on the radio button
177 * @param icon the image that the button should display
178 */
179 public JRadioButton (String text, Icon icon, boolean selected) {
180 super(text, icon, selected);
181 setBorderPainted(false);
182 setHorizontalAlignment(LEADING);
183 }
184
185
186 /**
187 * Resets the UI property to a value from the current look and feel.
188 *
189 * @see JComponent#updateUI
190 */
191 public void updateUI() {
192 setUI((ButtonUI)UIManager.getUI(this));
193 }
194
195
196 /**
197 * Returns the name of the L&F class
198 * that renders this component.
199 *
200 * @return String "RadioButtonUI"
201 * @see JComponent#getUIClassID
202 * @see UIDefaults#getUI
203 * @beaninfo
204 * expert: true
205 * description: A string that specifies the name of the L&F class.
206 */
207 public String getUIClassID() {
208 return uiClassID;
209 }
210
211
212 /**
213 * The icon for radio buttons comes from the look and feel,
214 * not the Action.
215 */
216 void setIconFromAction(Action a) {
217 }
218
219 /**
220 * See readObject() and writeObject() in JComponent for more
221 * information about serialization in Swing.
222 */
223 private void writeObject(ObjectOutputStream s) throws IOException {
224 s.defaultWriteObject();
225 if (getUIClassID().equals(uiClassID)) {
226 byte count = JComponent.getWriteObjCounter(this);
227 JComponent.setWriteObjCounter(this, --count);
228 if (count == 0 && ui != null) {
229 ui.installUI(this);
230 }
231 }
232 }
233
234
235 /**
236 * Returns a string representation of this JRadioButton. This method
237 * is intended to be used only for debugging purposes, and the
238 * content and format of the returned string may vary between
239 * implementations. The returned string may be empty but may not
240 * be <code>null</code>.
241 *
242 * @return a string representation of this JRadioButton.
243 */
244 protected String paramString() {
245 return super.paramString();
246 }
247
248
249 /////////////////
250 // Accessibility support
251 ////////////////
252
253
254 /**
255 * Gets the AccessibleContext associated with this JRadioButton.
256 * For JRadioButtons, the AccessibleContext takes the form of an
257 * AccessibleJRadioButton.
258 * A new AccessibleJRadioButton instance is created if necessary.
259 *
260 * @return an AccessibleJRadioButton that serves as the
261 * AccessibleContext of this JRadioButton
262 * @beaninfo
263 * expert: true
264 * description: The AccessibleContext associated with this Button
265 */
266 public AccessibleContext getAccessibleContext() {
267 if (accessibleContext == null) {
268 accessibleContext = new AccessibleJRadioButton();
269 }
270 return accessibleContext;
271 }
272
273 /**
274 * This class implements accessibility support for the
275 * <code>JRadioButton</code> class. It provides an implementation of the
276 * Java Accessibility API appropriate to radio button
277 * user-interface elements.
278 * <p>
279 * <strong>Warning:</strong>
280 * Serialized objects of this class will not be compatible with
281 * future Swing releases. The current serialization support is
282 * appropriate for short term storage or RMI between applications running
283 * the same version of Swing. As of 1.4, support for long term storage
284 * of all JavaBeans™
285 * has been added to the <code>java.beans</code> package.
286 * Please see {@link java.beans.XMLEncoder}.
287 */
288 @SuppressWarnings("serial") // Same-version serialization only
289 protected class AccessibleJRadioButton extends AccessibleJToggleButton {
290
291 /**
292 * Get the role of this object.
293 *
294 * @return an instance of AccessibleRole describing the role of the object
295 * @see AccessibleRole
296 */
297 public AccessibleRole getAccessibleRole() {
298 return AccessibleRole.RADIO_BUTTON;
299 }
300
301 } // inner class AccessibleJRadioButton
302 }