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24 */
25 package javax.swing;
26
27 import java.awt.*;
28 import java.awt.event.*;
29 import java.beans.*;
30
31 /**
32 * The <code>Action</code> interface provides a useful extension to the
33 * <code>ActionListener</code>
34 * interface in cases where the same functionality may be accessed by
35 * several controls.
36 * <p>
37 * In addition to the <code>actionPerformed</code> method defined by the
38 * <code>ActionListener</code> interface, this interface allows the
39 * application to define, in a single place:
40 * <ul>
41 * <li>One or more text strings that describe the function. These strings
42 * can be used, for example, to display the flyover text for a button
43 * or to set the text in a menu item.
44 * <li>One or more icons that depict the function. These icons can be used
45 * for the images in a menu control, or for composite entries in a more
46 * sophisticated user interface.
47 * <li>The enabled/disabled state of the functionality. Instead of having
48 * to separately disable the menu item and the toolbar button, the
49 * application can disable the function that implements this interface.
50 * All components which are registered as listeners for the state change
51 * then know to disable event generation for that item and to modify the
52 * display accordingly.
53 * </ul>
54 * <p>
55 * This interface can be added to an existing class or used to create an
56 * adapter (typically, by subclassing <code>AbstractAction</code>).
57 * The <code>Action</code> object
58 * can then be added to multiple <code>Action</code>-aware containers
59 * and connected to <code>Action</code>-capable
60 * components. The GUI controls can then be activated or
61 * deactivated all at once by invoking the <code>Action</code> object's
62 * <code>setEnabled</code> method.
63 * <p>
64 * Note that <code>Action</code> implementations tend to be more expensive
65 * in terms of storage than a typical <code>ActionListener</code>,
66 * which does not offer the benefits of centralized control of
67 * functionality and broadcast of property changes. For this reason,
68 * you should take care to only use <code>Action</code>s where their benefits
69 * are desired, and use simple <code>ActionListener</code>s elsewhere.
70 * <br>
71 *
72 * <h3><a name="buttonActions"></a>Swing Components Supporting <code>Action</code></h3>
73 * <p>
74 * Many of Swing's components have an <code>Action</code> property. When
75 * an <code>Action</code> is set on a component, the following things
76 * happen:
77 * <ul>
78 * <li>The <code>Action</code> is added as an <code>ActionListener</code> to
79 * the component.
80 * <li>The component configures some of its properties to match the
81 * <code>Action</code>.
82 * <li>The component installs a <code>PropertyChangeListener</code> on the
83 * <code>Action</code> so that the component can change its properties
84 * to reflect changes in the <code>Action</code>'s properties.
85 * </ul>
86 * <p>
87 * The following table describes the properties used by
88 * <code>Swing</code> components that support <code>Actions</code>.
89 * In the table, <em>button</em> refers to any
90 * <code>AbstractButton</code> subclass, which includes not only
91 * <code>JButton</code> but also classes such as
92 * <code>JMenuItem</code>. Unless otherwise stated, a
93 * <code>null</code> property value in an <code>Action</code> (or a
94 * <code>Action</code> that is <code>null</code>) results in the
95 * button's corresponding property being set to <code>null</code>.
96 *
97 * <table border="1" cellpadding="1" cellspacing="0"
98 * summary="Supported Action properties">
99 * <tr valign="top" align="left">
100 * <th style="background-color:#CCCCFF" align="left">Component Property
101 * <th style="background-color:#CCCCFF" align="left">Components
102 * <th style="background-color:#CCCCFF" align="left">Action Key
103 * <th style="background-color:#CCCCFF" align="left">Notes
104 * <tr valign="top" align="left">
105 * <td><b><code>enabled</code></b>
106 * <td>All
107 * <td>The <code>isEnabled</code> method
108 * <td>
109 * <tr valign="top" align="left">
110 * <td><b><code>toolTipText</code></b>
111 * <td>All
112 * <td><code>SHORT_DESCRIPTION</code>
113 * <td>
114 * <tr valign="top" align="left">
115 * <td><b><code>actionCommand</code></b>
116 * <td>All
117 * <td><code>ACTION_COMMAND_KEY</code>
118 * <td>
119 * <tr valign="top" align="left">
120 * <td><b><code>mnemonic</code></b>
121 * <td>All buttons
122 * <td><code>MNEMONIC_KEY</code>
123 * <td>A <code>null</code> value or <code>Action</code> results in the
124 * button's <code>mnemonic</code> property being set to
125 * <code>'\0'</code>.
126 * <tr valign="top" align="left">
127 * <td><b><code>text</code></b>
128 * <td>All buttons
129 * <td><code>NAME</code>
130 * <td>If you do not want the text of the button to mirror that
131 * of the <code>Action</code>, set the property
132 * <code>hideActionText</code> to <code>true</code>. If
133 * <code>hideActionText</code> is <code>true</code>, setting the
134 * <code>Action</code> changes the text of the button to
135 * <code>null</code> and any changes to <code>NAME</code>
136 * are ignored. <code>hideActionText</code> is useful for
137 * tool bar buttons that typically only show an <code>Icon</code>.
138 * <code>JToolBar.add(Action)</code> sets the property to
139 * <code>true</code> if the <code>Action</code> has a
140 * non-<code>null</code> value for <code>LARGE_ICON_KEY</code> or
141 * <code>SMALL_ICON</code>.
142 * <tr valign="top" align="left">
143 * <td><b><code>displayedMnemonicIndex</code></b>
144 * <td>All buttons
145 * <td><code>DISPLAYED_MNEMONIC_INDEX_KEY</code>
146 * <td>If the value of <code>DISPLAYED_MNEMONIC_INDEX_KEY</code> is
147 * beyond the bounds of the text, it is ignored. When
148 * <code>setAction</code> is called, if the value from the
149 * <code>Action</code> is <code>null</code>, the displayed
150 * mnemonic index is not updated. In any subsequent changes to
151 * <code>DISPLAYED_MNEMONIC_INDEX_KEY</code>, <code>null</code>
152 * is treated as -1.
153 * <tr valign="top" align="left">
154 * <td><b><code>icon</code></b>
155 * <td>All buttons except of <code>JCheckBox</code>,
156 * <code>JToggleButton</code> and <code>JRadioButton</code>.
157 * <td>either <code>LARGE_ICON_KEY</code> or
158 * <code>SMALL_ICON</code>
159 * <td>The <code>JMenuItem</code> subclasses only use
160 * <code>SMALL_ICON</code>. All other buttons will use
161 * <code>LARGE_ICON_KEY</code>; if the value is <code>null</code> they
162 * use <code>SMALL_ICON</code>.
163 * <tr valign="top" align="left">
164 * <td><b><code>accelerator</code></b>
165 * <td>All <code>JMenuItem</code> subclasses, with the exception of
166 * <code>JMenu</code>.
167 * <td><code>ACCELERATOR_KEY</code>
168 * <td>
169 * <tr valign="top" align="left">
170 * <td><b><code>selected</code></b>
171 * <td><code>JToggleButton</code>, <code>JCheckBox</code>,
172 * <code>JRadioButton</code>, <code>JCheckBoxMenuItem</code> and
173 * <code>JRadioButtonMenuItem</code>
174 * <td><code>SELECTED_KEY</code>
175 * <td>Components that honor this property only use
176 * the value if it is {@code non-null}. For example, if
177 * you set an {@code Action} that has a {@code null}
178 * value for {@code SELECTED_KEY} on a {@code JToggleButton}, the
179 * {@code JToggleButton} will not update it's selected state in
180 * any way. Similarly, any time the {@code JToggleButton}'s
181 * selected state changes it will only set the value back on
182 * the {@code Action} if the {@code Action} has a {@code non-null}
183 * value for {@code SELECTED_KEY}.
184 * <br>
185 * Components that honor this property keep their selected state
186 * in sync with this property. When the same {@code Action} is used
187 * with multiple components, all the components keep their selected
188 * state in sync with this property. Mutually exclusive
189 * buttons, such as {@code JToggleButton}s in a {@code ButtonGroup},
190 * force only one of the buttons to be selected. As such, do not
191 * use the same {@code Action} that defines a value for the
192 * {@code SELECTED_KEY} property with multiple mutually
193 * exclusive buttons.
194 * </table>
195 * <p>
196 * <code>JPopupMenu</code>, <code>JToolBar</code> and <code>JMenu</code>
197 * all provide convenience methods for creating a component and setting the
198 * <code>Action</code> on the corresponding component. Refer to each of
199 * these classes for more information.
200 * <p>
201 * <code>Action</code> uses <code>PropertyChangeListener</code> to
202 * inform listeners the <code>Action</code> has changed. The beans
203 * specification indicates that a <code>null</code> property name can
204 * be used to indicate multiple values have changed. By default Swing
205 * components that take an <code>Action</code> do not handle such a
206 * change. To indicate that Swing should treat <code>null</code>
207 * according to the beans specification set the system property
208 * <code>swing.actions.reconfigureOnNull</code> to the <code>String</code>
209 * value <code>true</code>.
210 *
211 * @author Georges Saab
212 * @see AbstractAction
213 */
214 public interface Action extends ActionListener {
215 /**
216 * Useful constants that can be used as the storage-retrieval key
217 * when setting or getting one of this object's properties (text
218 * or icon).
219 */
220 /**
221 * Not currently used.
222 */
223 public static final String DEFAULT = "Default";
224 /**
225 * The key used for storing the <code>String</code> name
226 * for the action, used for a menu or button.
227 */
228 public static final String NAME = "Name";
229 /**
230 * The key used for storing a short <code>String</code>
231 * description for the action, used for tooltip text.
232 */
233 public static final String SHORT_DESCRIPTION = "ShortDescription";
234 /**
235 * The key used for storing a longer <code>String</code>
236 * description for the action, could be used for context-sensitive help.
237 */
238 public static final String LONG_DESCRIPTION = "LongDescription";
239 /**
240 * The key used for storing a small <code>Icon</code>, such
241 * as <code>ImageIcon</code>. This is typically used with
242 * menus such as <code>JMenuItem</code>.
243 * <p>
244 * If the same <code>Action</code> is used with menus and buttons you'll
245 * typically specify both a <code>SMALL_ICON</code> and a
246 * <code>LARGE_ICON_KEY</code>. The menu will use the
247 * <code>SMALL_ICON</code> and the button will use the
248 * <code>LARGE_ICON_KEY</code>.
249 */
250 public static final String SMALL_ICON = "SmallIcon";
251
252 /**
253 * The key used to determine the command <code>String</code> for the
254 * <code>ActionEvent</code> that will be created when an
255 * <code>Action</code> is going to be notified as the result of
256 * residing in a <code>Keymap</code> associated with a
257 * <code>JComponent</code>.
258 */
259 public static final String ACTION_COMMAND_KEY = "ActionCommandKey";
260
261 /**
262 * The key used for storing a <code>KeyStroke</code> to be used as the
263 * accelerator for the action.
264 *
265 * @since 1.3
266 */
267 public static final String ACCELERATOR_KEY="AcceleratorKey";
268
269 /**
270 * The key used for storing an <code>Integer</code> that corresponds to
271 * one of the <code>KeyEvent</code> key codes. The value is
272 * commonly used to specify a mnemonic. For example:
273 * <code>myAction.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_A)</code>
274 * sets the mnemonic of <code>myAction</code> to 'a', while
275 * <code>myAction.putValue(Action.MNEMONIC_KEY, KeyEvent.getExtendedKeyCodeForChar('\u0444'))</code>
276 * sets the mnemonic of <code>myAction</code> to Cyrillic letter "Ef".
277 *
278 * @since 1.3
279 */
280 public static final String MNEMONIC_KEY="MnemonicKey";
281
282 /**
283 * The key used for storing a <code>Boolean</code> that corresponds
284 * to the selected state. This is typically used only for components
285 * that have a meaningful selection state. For example,
286 * <code>JRadioButton</code> and <code>JCheckBox</code> make use of
287 * this but instances of <code>JMenu</code> don't.
288 * <p>
289 * This property differs from the others in that it is both read
290 * by the component and set by the component. For example,
291 * if an <code>Action</code> is attached to a <code>JCheckBox</code>
292 * the selected state of the <code>JCheckBox</code> will be set from
293 * that of the <code>Action</code>. If the user clicks on the
294 * <code>JCheckBox</code> the selected state of the <code>JCheckBox</code>
295 * <b>and</b> the <code>Action</code> will <b>both</b> be updated.
296 * <p>
297 * Note: the value of this field is prefixed with 'Swing' to
298 * avoid possible collisions with existing <code>Actions</code>.
299 *
300 * @since 1.6
301 */
302 public static final String SELECTED_KEY = "SwingSelectedKey";
303
304 /**
305 * The key used for storing an <code>Integer</code> that corresponds
306 * to the index in the text (identified by the <code>NAME</code>
307 * property) that the decoration for a mnemonic should be rendered at. If
308 * the value of this property is greater than or equal to the length of
309 * the text, it will treated as -1.
310 * <p>
311 * Note: the value of this field is prefixed with 'Swing' to
312 * avoid possible collisions with existing <code>Actions</code>.
313 *
314 * @see AbstractButton#setDisplayedMnemonicIndex
315 * @since 1.6
316 */
317 public static final String DISPLAYED_MNEMONIC_INDEX_KEY =
318 "SwingDisplayedMnemonicIndexKey";
319
320 /**
321 * The key used for storing an <code>Icon</code>. This is typically
322 * used by buttons, such as <code>JButton</code> and
323 * <code>JToggleButton</code>.
324 * <p>
325 * If the same <code>Action</code> is used with menus and buttons you'll
326 * typically specify both a <code>SMALL_ICON</code> and a
327 * <code>LARGE_ICON_KEY</code>. The menu will use the
328 * <code>SMALL_ICON</code> and the button the <code>LARGE_ICON_KEY</code>.
329 * <p>
330 * Note: the value of this field is prefixed with 'Swing' to
331 * avoid possible collisions with existing <code>Actions</code>.
332 *
333 * @since 1.6
334 */
335 public static final String LARGE_ICON_KEY = "SwingLargeIconKey";
336
337 /**
338 * Gets one of this object's properties
339 * using the associated key.
340 * @see #putValue
341 */
342 public Object getValue(String key);
343 /**
344 * Sets one of this object's properties
345 * using the associated key. If the value has
346 * changed, a <code>PropertyChangeEvent</code> is sent
347 * to listeners.
348 *
349 * @param key a <code>String</code> containing the key
350 * @param value an <code>Object</code> value
351 */
352 public void putValue(String key, Object value);
353
354 /**
355 * Sets the enabled state of the <code>Action</code>. When enabled,
356 * any component associated with this object is active and
357 * able to fire this object's <code>actionPerformed</code> method.
358 * If the value has changed, a <code>PropertyChangeEvent</code> is sent
359 * to listeners.
360 *
361 * @param b true to enable this <code>Action</code>, false to disable it
362 */
363 public void setEnabled(boolean b);
364 /**
365 * Returns the enabled state of the <code>Action</code>. When enabled,
366 * any component associated with this object is active and
367 * able to fire this object's <code>actionPerformed</code> method.
368 *
369 * @return true if this <code>Action</code> is enabled
370 */
371 public boolean isEnabled();
372
373 /**
374 * Adds a <code>PropertyChange</code> listener. Containers and attached
375 * components use these methods to register interest in this
376 * <code>Action</code> object. When its enabled state or other property
377 * changes, the registered listeners are informed of the change.
378 *
379 * @param listener a <code>PropertyChangeListener</code> object
380 */
381 public void addPropertyChangeListener(PropertyChangeListener listener);
382 /**
383 * Removes a <code>PropertyChange</code> listener.
384 *
385 * @param listener a <code>PropertyChangeListener</code> object
386 * @see #addPropertyChangeListener
387 */
388 public void removePropertyChangeListener(PropertyChangeListener listener);
389
390 }