1 /*
2 * Copyright (c) 1997, 2013, 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.beans.ConstructorProperties;
28
29 import java.awt.*;
30 import java.awt.event.*;
31 import java.awt.image.*;
32
33 import javax.swing.plaf.*;
34 import javax.swing.event.*;
35 import javax.accessibility.*;
36
37 import java.io.ObjectOutputStream;
38 import java.io.ObjectInputStream;
39 import java.io.IOException;
40
41
42 /**
43 * An implementation of a "push" button.
44 * <p>
45 * Buttons can be configured, and to some degree controlled, by
46 * <code><a href="Action.html">Action</a></code>s. Using an
47 * <code>Action</code> with a button has many benefits beyond directly
48 * configuring a button. Refer to <a href="Action.html#buttonActions">
49 * Swing Components Supporting <code>Action</code></a> for more
50 * details, and you can find more information in <a
51 * href="http://docs.oracle.com/javase/tutorial/uiswing/misc/action.html">How
52 * to Use Actions</a>, a section in <em>The Java Tutorial</em>.
53 * <p>
54 * See <a href="http://docs.oracle.com/javase/tutorial/uiswing/components/button.html">How to Use Buttons, Check Boxes, and Radio Buttons</a>
55 * in <em>The Java Tutorial</em>
56 * for information and examples of using buttons.
57 * <p>
58 * <strong>Warning:</strong> Swing is not thread safe. For more
59 * information see <a
60 * href="package-summary.html#threading">Swing's Threading
61 * Policy</a>.
62 * <p>
63 * <strong>Warning:</strong>
64 * Serialized objects of this class will not be compatible with
65 * future Swing releases. The current serialization support is
66 * appropriate for short term storage or RMI between applications running
67 * the same version of Swing. As of 1.4, support for long term storage
68 * of all JavaBeans™
69 * has been added to the <code>java.beans</code> package.
70 * Please see {@link java.beans.XMLEncoder}.
71 *
72 * @beaninfo
73 * attribute: isContainer false
74 * description: An implementation of a \"push\" button.
75 *
76 * @author Jeff Dinkins
77 * @since 1.2
78 */
79 @SuppressWarnings("serial")
80 public class JButton extends AbstractButton implements Accessible {
81
82 /**
83 * @see #getUIClassID
84 * @see #readObject
85 */
86 private static final String uiClassID = "ButtonUI";
87
88 /**
89 * Creates a button with no set text or icon.
90 */
91 public JButton() {
92 this(null, null);
93 }
94
95 /**
96 * Creates a button with an icon.
97 *
98 * @param icon the Icon image to display on the button
99 */
100 public JButton(Icon icon) {
101 this(null, icon);
102 }
103
104 /**
105 * Creates a button with text.
106 *
107 * @param text the text of the button
108 */
109 @ConstructorProperties({"text"})
110 public JButton(String text) {
111 this(text, null);
112 }
113
114 /**
115 * Creates a button where properties are taken from the
116 * <code>Action</code> supplied.
117 *
118 * @param a the <code>Action</code> used to specify the new button
119 *
120 * @since 1.3
121 */
122 public JButton(Action a) {
123 this();
124 setAction(a);
125 }
126
127 /**
128 * Creates a button with initial text and an icon.
129 *
130 * @param text the text of the button
131 * @param icon the Icon image to display on the button
132 */
133 public JButton(String text, Icon icon) {
134 // Create the model
135 setModel(new DefaultButtonModel());
136
137 // initialize
138 init(text, icon);
139 }
140
141 /**
142 * Resets the UI property to a value from the current look and
143 * feel.
144 *
145 * @see JComponent#updateUI
146 */
147 public void updateUI() {
148 setUI((ButtonUI)UIManager.getUI(this));
149 }
150
151
152 /**
153 * Returns a string that specifies the name of the L&F class
154 * that renders this component.
155 *
156 * @return the string "ButtonUI"
157 * @see JComponent#getUIClassID
158 * @see UIDefaults#getUI
159 * @beaninfo
160 * expert: true
161 * description: A string that specifies the name of the L&F class.
162 */
163 public String getUIClassID() {
164 return uiClassID;
165 }
166
167
168 /**
169 * Gets the value of the <code>defaultButton</code> property,
170 * which if <code>true</code> means that this button is the current
171 * default button for its <code>JRootPane</code>.
172 * Most look and feels render the default button
173 * differently, and may potentially provide bindings
174 * to access the default button.
175 *
176 * @return the value of the <code>defaultButton</code> property
177 * @see JRootPane#setDefaultButton
178 * @see #isDefaultCapable
179 * @beaninfo
180 * description: Whether or not this button is the default button
181 */
182 public boolean isDefaultButton() {
183 JRootPane root = SwingUtilities.getRootPane(this);
184 if (root != null) {
185 return root.getDefaultButton() == this;
186 }
187 return false;
188 }
189
190 /**
191 * Gets the value of the <code>defaultCapable</code> property.
192 *
193 * @return the value of the <code>defaultCapable</code> property
194 * @see #setDefaultCapable
195 * @see #isDefaultButton
196 * @see JRootPane#setDefaultButton
197 */
198 public boolean isDefaultCapable() {
199 return defaultCapable;
200 }
201
202 /**
203 * Sets the <code>defaultCapable</code> property,
204 * which determines whether this button can be
205 * made the default button for its root pane.
206 * The default value of the <code>defaultCapable</code>
207 * property is <code>true</code> unless otherwise
208 * specified by the look and feel.
209 *
210 * @param defaultCapable <code>true</code> if this button will be
211 * capable of being the default button on the
212 * <code>RootPane</code>; otherwise <code>false</code>
213 * @see #isDefaultCapable
214 * @beaninfo
215 * bound: true
216 * attribute: visualUpdate true
217 * description: Whether or not this button can be the default button
218 */
219 public void setDefaultCapable(boolean defaultCapable) {
220 boolean oldDefaultCapable = this.defaultCapable;
221 this.defaultCapable = defaultCapable;
222 firePropertyChange("defaultCapable", oldDefaultCapable, defaultCapable);
223 }
224
225 /**
226 * Overrides <code>JComponent.removeNotify</code> to check if
227 * this button is currently set as the default button on the
228 * <code>RootPane</code>, and if so, sets the <code>RootPane</code>'s
229 * default button to <code>null</code> to ensure the
230 * <code>RootPane</code> doesn't hold onto an invalid button reference.
231 */
232 public void removeNotify() {
233 JRootPane root = SwingUtilities.getRootPane(this);
234 if (root != null && root.getDefaultButton() == this) {
235 root.setDefaultButton(null);
236 }
237 super.removeNotify();
238 }
239
240 /**
241 * See readObject() and writeObject() in JComponent for more
242 * information about serialization in Swing.
243 */
244 private void writeObject(ObjectOutputStream s) throws IOException {
245 s.defaultWriteObject();
246 if (getUIClassID().equals(uiClassID)) {
247 byte count = JComponent.getWriteObjCounter(this);
248 JComponent.setWriteObjCounter(this, --count);
249 if (count == 0 && ui != null) {
250 ui.installUI(this);
251 }
252 }
253 }
254
255
256 /**
257 * Returns a string representation of this <code>JButton</code>.
258 * This method is intended to be used only for debugging purposes, and the
259 * content and format of the returned string may vary between
260 * implementations. The returned string may be empty but may not
261 * be <code>null</code>.
262 *
263 * @return a string representation of this <code>JButton</code>
264 */
265 protected String paramString() {
266 String defaultCapableString = (defaultCapable ? "true" : "false");
267
268 return super.paramString() +
269 ",defaultCapable=" + defaultCapableString;
270 }
271
272
273 /////////////////
274 // Accessibility support
275 ////////////////
276
277 /**
278 * Gets the <code>AccessibleContext</code> associated with this
279 * <code>JButton</code>. For <code>JButton</code>s,
280 * the <code>AccessibleContext</code> takes the form of an
281 * <code>AccessibleJButton</code>.
282 * A new <code>AccessibleJButton</code> instance is created if necessary.
283 *
284 * @return an <code>AccessibleJButton</code> that serves as the
285 * <code>AccessibleContext</code> of this <code>JButton</code>
286 * @beaninfo
287 * expert: true
288 * description: The AccessibleContext associated with this Button.
289 */
290 public AccessibleContext getAccessibleContext() {
291 if (accessibleContext == null) {
292 accessibleContext = new AccessibleJButton();
293 }
294 return accessibleContext;
295 }
296
297 /**
298 * This class implements accessibility support for the
299 * <code>JButton</code> class. It provides an implementation of the
300 * Java Accessibility API appropriate to button user-interface
301 * elements.
302 * <p>
303 * <strong>Warning:</strong>
304 * Serialized objects of this class will not be compatible with
305 * future Swing releases. The current serialization support is
306 * appropriate for short term storage or RMI between applications running
307 * the same version of Swing. As of 1.4, support for long term storage
308 * of all JavaBeans™
309 * has been added to the <code>java.beans</code> package.
310 * Please see {@link java.beans.XMLEncoder}.
311 */
312 @SuppressWarnings("serial")
313 protected class AccessibleJButton extends AccessibleAbstractButton {
314
315 /**
316 * Get the role of this object.
317 *
318 * @return an instance of AccessibleRole describing the role of the
319 * object
320 * @see AccessibleRole
321 */
322 public AccessibleRole getAccessibleRole() {
323 return AccessibleRole.PUSH_BUTTON;
324 }
325 } // inner class AccessibleJButton
326 }