1 /* 2 * Copyright (c) 1997, 2017, 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 /** 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 * @since 1.2 214 */ 215 public interface Action extends ActionListener { 216 /** 217 * Useful constants that can be used as the storage-retrieval key 218 * when setting or getting one of this object's properties (text 219 * or icon). 220 */ 221 /** 222 * Not currently used. 223 */ 224 public static final String DEFAULT = "Default"; 225 /** 226 * The key used for storing the <code>String</code> name 227 * for the action, used for a menu or button. 228 */ 229 public static final String NAME = "Name"; 230 /** 231 * The key used for storing a short <code>String</code> 232 * description for the action, used for tooltip text. 233 */ 234 public static final String SHORT_DESCRIPTION = "ShortDescription"; 235 /** 236 * The key used for storing a longer <code>String</code> 237 * description for the action, could be used for context-sensitive help. 238 */ 239 public static final String LONG_DESCRIPTION = "LongDescription"; 240 /** 241 * The key used for storing a small <code>Icon</code>, such 242 * as <code>ImageIcon</code>. This is typically used with 243 * menus such as <code>JMenuItem</code>. 244 * <p> 245 * If the same <code>Action</code> is used with menus and buttons you'll 246 * typically specify both a <code>SMALL_ICON</code> and a 247 * <code>LARGE_ICON_KEY</code>. The menu will use the 248 * <code>SMALL_ICON</code> and the button will use the 249 * <code>LARGE_ICON_KEY</code>. 250 */ 251 public static final String SMALL_ICON = "SmallIcon"; 252 253 /** 254 * The key used to determine the command <code>String</code> for the 255 * <code>ActionEvent</code> that will be created when an 256 * <code>Action</code> is going to be notified as the result of 257 * residing in a <code>Keymap</code> associated with a 258 * <code>JComponent</code>. 259 */ 260 public static final String ACTION_COMMAND_KEY = "ActionCommandKey"; 261 262 /** 263 * The key used for storing a <code>KeyStroke</code> to be used as the 264 * accelerator for the action. 265 * 266 * @since 1.3 267 */ 268 public static final String ACCELERATOR_KEY="AcceleratorKey"; 269 270 /** 271 * The key used for storing an <code>Integer</code> that corresponds to 272 * one of the <code>KeyEvent</code> key codes. The value is 273 * commonly used to specify a mnemonic. For example: 274 * <code>myAction.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_A)</code> 275 * sets the mnemonic of <code>myAction</code> to 'a', while 276 * <code>myAction.putValue(Action.MNEMONIC_KEY, KeyEvent.getExtendedKeyCodeForChar('\u0444'))</code> 277 * sets the mnemonic of <code>myAction</code> to Cyrillic letter "Ef". 278 * 279 * @since 1.3 280 */ 281 public static final String MNEMONIC_KEY="MnemonicKey"; 282 283 /** 284 * The key used for storing a <code>Boolean</code> that corresponds 285 * to the selected state. This is typically used only for components 286 * that have a meaningful selection state. For example, 287 * <code>JRadioButton</code> and <code>JCheckBox</code> make use of 288 * this but instances of <code>JMenu</code> don't. 289 * <p> 290 * This property differs from the others in that it is both read 291 * by the component and set by the component. For example, 292 * if an <code>Action</code> is attached to a <code>JCheckBox</code> 293 * the selected state of the <code>JCheckBox</code> will be set from 294 * that of the <code>Action</code>. If the user clicks on the 295 * <code>JCheckBox</code> the selected state of the <code>JCheckBox</code> 296 * <b>and</b> the <code>Action</code> will <b>both</b> be updated. 297 * <p> 298 * Note: the value of this field is prefixed with 'Swing' to 299 * avoid possible collisions with existing <code>Actions</code>. 300 * 301 * @since 1.6 302 */ 303 public static final String SELECTED_KEY = "SwingSelectedKey"; 304 305 /** 306 * The key used for storing an <code>Integer</code> that corresponds 307 * to the index in the text (identified by the <code>NAME</code> 308 * property) that the decoration for a mnemonic should be rendered at. If 309 * the value of this property is greater than or equal to the length of 310 * the text, it will treated as -1. 311 * <p> 312 * Note: the value of this field is prefixed with 'Swing' to 313 * avoid possible collisions with existing <code>Actions</code>. 314 * 315 * @see AbstractButton#setDisplayedMnemonicIndex 316 * @since 1.6 317 */ 318 public static final String DISPLAYED_MNEMONIC_INDEX_KEY = 319 "SwingDisplayedMnemonicIndexKey"; 320 321 /** 322 * The key used for storing an <code>Icon</code>. This is typically 323 * used by buttons, such as <code>JButton</code> and 324 * <code>JToggleButton</code>. 325 * <p> 326 * If the same <code>Action</code> is used with menus and buttons you'll 327 * typically specify both a <code>SMALL_ICON</code> and a 328 * <code>LARGE_ICON_KEY</code>. The menu will use the 329 * <code>SMALL_ICON</code> and the button the <code>LARGE_ICON_KEY</code>. 330 * <p> 331 * Note: the value of this field is prefixed with 'Swing' to 332 * avoid possible collisions with existing <code>Actions</code>. 333 * 334 * @since 1.6 335 */ 336 public static final String LARGE_ICON_KEY = "SwingLargeIconKey"; 337 338 /** 339 * Gets one of this object's properties 340 * using the associated key. 341 * 342 * @param key a {@code String} containing the key 343 * @return the {@code Object} value 344 * @see #putValue 345 */ 346 public Object getValue(String key); 347 /** 348 * Sets one of this object's properties 349 * using the associated key. If the value has 350 * changed, a <code>PropertyChangeEvent</code> is sent 351 * to listeners. 352 * 353 * @param key a <code>String</code> containing the key 354 * @param value an <code>Object</code> value 355 */ 356 public void putValue(String key, Object value); 357 358 /** 359 * Sets the enabled state of the {@code Action}. When enabled, 360 * any component associated with this object is active and 361 * able to fire this object's {@code actionPerformed} method. 362 * If the value has changed, a {@code PropertyChangeEvent} is sent 363 * to listeners. 364 * 365 * @param b true to enable this {@code Action}, false to disable it 366 * @see #accept 367 */ 368 public void setEnabled(boolean b); 369 /** 370 * Returns the enabled state of the {@code Action}. When enabled, 371 * any component associated with this object is active and 372 * able to fire this object's {@code actionPerformed} method. 373 * 374 * @return true if this {@code Action} is enabled 375 * @see #accept 376 */ 377 public boolean isEnabled(); 378 379 /** 380 * Determines whether the action should be performed with the specified 381 * sender object. The {@code sender} can be {@code null}. 382 * The method must return false if the action is disabled. 383 * <p> 384 * @param sender the object to check, can be null 385 * @return {@code true} if the action should be performed with the sender 386 * object, must be false if the action is disabled. 387 * @see #isEnabled 388 * @see #setEnabled 389 */ 390 default boolean accept(Object sender) { 391 return isEnabled(); 392 } 393 394 /** 395 * Adds a <code>PropertyChange</code> listener. Containers and attached 396 * components use these methods to register interest in this 397 * <code>Action</code> object. When its enabled state or other property 398 * changes, the registered listeners are informed of the change. 399 * 400 * @param listener a <code>PropertyChangeListener</code> object 401 */ 402 public void addPropertyChangeListener(PropertyChangeListener listener); 403 /** 404 * Removes a <code>PropertyChange</code> listener. 405 * 406 * @param listener a <code>PropertyChangeListener</code> object 407 * @see #addPropertyChangeListener 408 */ 409 public void removePropertyChangeListener(PropertyChangeListener listener); 410 411 }