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