Home » openjdk-7 » javax » swing » [javadoc | source]

    1   /*
    2    * Copyright (c) 1997, 2009, 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    * <p>
   71    *
   72    * <h4><a name="buttonActions"></a>Swing Components Supporting <code>Action</code></h4>
   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    * <p>
   97    * <table border="1" cellpadding="1" cellspacing="0"
   98    *         summary="Supported Action properties"
   99    *         valign="top" >
  100    *  <tr valign="top"  align="left">
  101    *    <th bgcolor="#CCCCFF" align="left">Component Property
  102    *    <th bgcolor="#CCCCFF" align="left">Components
  103    *    <th bgcolor="#CCCCFF" align="left">Action Key
  104    *    <th bgcolor="#CCCCFF" align="left">Notes
  105    *  <tr valign="top"  align="left">
  106    *      <td><b><code>enabled</code></b>
  107    *      <td>All
  108    *      <td>The <code>isEnabled</code> method
  109    *      <td>&nbsp;
  110    *  <tr valign="top"  align="left">
  111    *      <td><b><code>toolTipText</code></b>
  112    *      <td>All
  113    *      <td><code>SHORT_DESCRIPTION</code>
  114    *      <td>&nbsp;
  115    *  <tr valign="top"  align="left">
  116    *      <td><b><code>actionCommand</code></b>
  117    *      <td>All
  118    *      <td><code>ACTION_COMMAND_KEY</code>
  119    *      <td>&nbsp;
  120    *  <tr valign="top"  align="left">
  121    *      <td><b><code>mnemonic</code></b>
  122    *      <td>All buttons
  123    *      <td><code>MNEMONIC_KEY</code>
  124    *      <td>A <code>null</code> value or <code>Action</code> results in the
  125    *          button's <code>mnemonic</code> property being set to
  126    *          <code>'\0'</code>.
  127    *  <tr valign="top"  align="left">
  128    *      <td><b><code>text</code></b>
  129    *      <td>All buttons
  130    *      <td><code>NAME</code>
  131    *      <td>If you do not want the text of the button to mirror that
  132    *          of the <code>Action</code>, set the property
  133    *          <code>hideActionText</code> to <code>true</code>.  If
  134    *          <code>hideActionText</code> is <code>true</code>, setting the
  135    *          <code>Action</code> changes the text of the button to
  136    *          <code>null</code> and any changes to <code>NAME</code>
  137    *          are ignored.  <code>hideActionText</code> is useful for
  138    *          tool bar buttons that typically only show an <code>Icon</code>.
  139    *          <code>JToolBar.add(Action)</code> sets the property to
  140    *          <code>true</code> if the <code>Action</code> has a
  141    *          non-<code>null</code> value for <code>LARGE_ICON_KEY</code> or
  142    *          <code>SMALL_ICON</code>.
  143    *  <tr valign="top"  align="left">
  144    *      <td><b><code>displayedMnemonicIndex</code></b>
  145    *      <td>All buttons
  146    *      <td><code>DISPLAYED_MNEMONIC_INDEX_KEY</code>
  147    *      <td>If the value of <code>DISPLAYED_MNEMONIC_INDEX_KEY</code> is
  148    *          beyond the bounds of the text, it is ignored.  When
  149    *          <code>setAction</code> is called, if the value from the
  150    *          <code>Action</code> is <code>null</code>, the displayed
  151    *          mnemonic index is not updated.  In any subsequent changes to
  152    *          <code>DISPLAYED_MNEMONIC_INDEX_KEY</code>, <code>null</code>
  153    *          is treated as -1.
  154    *  <tr valign="top"  align="left">
  155    *      <td><b><code>icon</code></b>
  156    *      <td>All buttons except of <code>JCheckBox</code>,
  157    *      <code>JToggleButton</code> and <code>JRadioButton</code>.
  158    *      <td>either <code>LARGE_ICON_KEY</code> or
  159    *          <code>SMALL_ICON</code>
  160    *     <td>The <code>JMenuItem</code> subclasses only use
  161    *         <code>SMALL_ICON</code>.  All other buttons will use
  162    *         <code>LARGE_ICON_KEY</code>; if the value is <code>null</code> they
  163    *         use <code>SMALL_ICON</code>.
  164    *  <tr valign="top"  align="left">
  165    *      <td><b><code>accelerator</code></b>
  166    *      <td>All <code>JMenuItem</code> subclasses, with the exception of
  167    *          <code>JMenu</code>.
  168    *      <td><code>ACCELERATOR_KEY</code>
  169    *      <td>&nbsp;
  170    *  <tr valign="top"  align="left">
  171    *      <td><b><code>selected</code></b>
  172    *      <td><code>JToggleButton</code>, <code>JCheckBox</code>,
  173    *          <code>JRadioButton</code>, <code>JCheckBoxMenuItem</code> and
  174    *          <code>JRadioButtonMenuItem</code>
  175    *      <td><code>SELECTED_KEY</code>
  176    *      <td>Components that honor this property only use
  177    *          the value if it is {@code non-null}. For example, if
  178    *          you set an {@code Action} that has a {@code null}
  179    *          value for {@code SELECTED_KEY} on a {@code JToggleButton}, the
  180    *          {@code JToggleButton} will not update it's selected state in
  181    *          any way. Similarly, any time the {@code JToggleButton}'s
  182    *          selected state changes it will only set the value back on
  183    *          the {@code Action} if the {@code Action} has a {@code non-null}
  184    *          value for {@code SELECTED_KEY}.
  185    *          <br>
  186    *          Components that honor this property keep their selected state
  187    *          in sync with this property. When the same {@code Action} is used
  188    *          with multiple components, all the components keep their selected
  189    *          state in sync with this property. Mutually exclusive
  190    *          buttons, such as {@code JToggleButton}s in a {@code ButtonGroup},
  191    *          force only one of the buttons to be selected. As such, do not
  192    *          use the same {@code Action} that defines a value for the
  193    *          {@code SELECTED_KEY} property with multiple mutually
  194    *          exclusive buttons.
  195    * </table>
  196    * <p>
  197    * <code>JPopupMenu</code>, <code>JToolBar</code> and <code>JMenu</code>
  198    * all provide convenience methods for creating a component and setting the
  199    * <code>Action</code> on the corresponding component.  Refer to each of
  200    * these classes for more information.
  201    * <p>
  202    * <code>Action</code> uses <code>PropertyChangeListener</code> to
  203    * inform listeners the <code>Action</code> has changed.  The beans
  204    * specification indicates that a <code>null</code> property name can
  205    * be used to indicate multiple values have changed.  By default Swing
  206    * components that take an <code>Action</code> do not handle such a
  207    * change.  To indicate that Swing should treat <code>null</code>
  208    * according to the beans specification set the system property
  209    * <code>swing.actions.reconfigureOnNull</code> to the <code>String</code>
  210    * value <code>true</code>.
  211    *
  212    * @author Georges Saab
  213    * @see AbstractAction
  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        * @see #putValue
  342        */
  343       public Object getValue(String key);
  344       /**
  345        * Sets one of this object's properties
  346        * using the associated key. If the value has
  347        * changed, a <code>PropertyChangeEvent</code> is sent
  348        * to listeners.
  349        *
  350        * @param key    a <code>String</code> containing the key
  351        * @param value  an <code>Object</code> value
  352        */
  353       public void putValue(String key, Object value);
  354   
  355       /**
  356        * Sets the enabled state of the <code>Action</code>.  When enabled,
  357        * any component associated with this object is active and
  358        * able to fire this object's <code>actionPerformed</code> method.
  359        * If the value has changed, a <code>PropertyChangeEvent</code> is sent
  360        * to listeners.
  361        *
  362        * @param  b true to enable this <code>Action</code>, false to disable it
  363        */
  364       public void setEnabled(boolean b);
  365       /**
  366        * Returns the enabled state of the <code>Action</code>. When enabled,
  367        * any component associated with this object is active and
  368        * able to fire this object's <code>actionPerformed</code> method.
  369        *
  370        * @return true if this <code>Action</code> is enabled
  371        */
  372       public boolean isEnabled();
  373   
  374       /**
  375        * Adds a <code>PropertyChange</code> listener. Containers and attached
  376        * components use these methods to register interest in this
  377        * <code>Action</code> object. When its enabled state or other property
  378        * changes, the registered listeners are informed of the change.
  379        *
  380        * @param listener  a <code>PropertyChangeListener</code> object
  381        */
  382       public void addPropertyChangeListener(PropertyChangeListener listener);
  383       /**
  384        * Removes a <code>PropertyChange</code> listener.
  385        *
  386        * @param listener  a <code>PropertyChangeListener</code> object
  387        * @see #addPropertyChangeListener
  388        */
  389       public void removePropertyChangeListener(PropertyChangeListener listener);
  390   
  391   }

Home » openjdk-7 » javax » swing » [javadoc | source]