/* * Copyright (c) 1997, 2009, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */package javax.swing; import java.awt.*;import java.awt.event.*;import java.beans.*; /** * The <code>Action</code> interface provides a useful extension to the * <code>ActionListener</code> * interface in cases where the same functionality may be accessed by * several controls. * <p> * In addition to the <code>actionPerformed</code> method defined by the * <code>ActionListener</code> interface, this interface allows the * application to define, in a single place: * <ul> * <li>One or more text strings that describe the function. These strings *     can be used, for example, to display the flyover text for a button *     or to set the text in a menu item. * <li>One or more icons that depict the function. These icons can be used *     for the images in a menu control, or for composite entries in a more *     sophisticated user interface. * <li>The enabled/disabled state of the functionality. Instead of having *     to separately disable the menu item and the toolbar button, the *     application can disable the function that implements this interface. *     All components which are registered as listeners for the state change *     then know to disable event generation for that item and to modify the *     display accordingly. * </ul> * <p> * This interface can be added to an existing class or used to create an * adapter (typically, by subclassing <code>AbstractAction</code>). * The <code>Action</code> object * can then be added to multiple <code>Action</code>-aware containers * and connected to <code>Action</code>-capable * components. The GUI controls can then be activated or * deactivated all at once by invoking the <code>Action</code> object's * <code>setEnabled</code> method. * <p> * Note that <code>Action</code> implementations tend to be more expensive * in terms of storage than a typical <code>ActionListener</code>, * which does not offer the benefits of centralized control of * functionality and broadcast of property changes.  For this reason, * you should take care to only use <code>Action</code>s where their benefits * are desired, and use simple <code>ActionListener</code>s elsewhere. * <p> * * <h4><a name="buttonActions"></a>Swing Components Supporting <code>Action</code></h4> * <p> * Many of Swing's components have an <code>Action</code> property.  When * an <code>Action</code> is set on a component, the following things * happen: * <ul> * <li>The <code>Action</code> is added as an <code>ActionListener</code> to *     the component. * <li>The component configures some of its properties to match the *      <code>Action</code>. * <li>The component installs a <code>PropertyChangeListener</code> on the *     <code>Action</code> so that the component can change its properties *     to reflect changes in the <code>Action</code>'s properties. * </ul> * <p> * The following table describes the properties used by * <code>Swing</code> components that support <code>Actions</code>. * In the table, <em>button</em> refers to any * <code>AbstractButton</code> subclass, which includes not only * <code>JButton</code> but also classes such as * <code>JMenuItem</code>. Unless otherwise stated, a * <code>null</code> property value in an <code>Action</code> (or a * <code>Action</code> that is <code>null</code>) results in the * button's corresponding property being set to <code>null</code>. * <p> * <table border="1" cellpadding="1" cellspacing="0" *         summary="Supported Action properties" *         valign="top" > *  <tr valign="top"  align="left"> *    <th bgcolor="#CCCCFF" align="left">Component Property *    <th bgcolor="#CCCCFF" align="left">Components *    <th bgcolor="#CCCCFF" align="left">Action Key *    <th bgcolor="#CCCCFF" align="left">Notes *  <tr valign="top"  align="left"> *      <td><b><code>enabled</code></b> *      <td>All *      <td>The <code>isEnabled</code> method *      <td>&nbsp; *  <tr valign="top"  align="left"> *      <td><b><code>toolTipText</code></b> *      <td>All *      <td><code>SHORT_DESCRIPTION</code> *      <td>&nbsp; *  <tr valign="top"  align="left"> *      <td><b><code>actionCommand</code></b> *      <td>All *      <td><code>ACTION_COMMAND_KEY</code> *      <td>&nbsp; *  <tr valign="top"  align="left"> *      <td><b><code>mnemonic</code></b> *      <td>All buttons *      <td><code>MNEMONIC_KEY</code> *      <td>A <code>null</code> value or <code>Action</code> results in the *          button's <code>mnemonic</code> property being set to *          <code>'\0'</code>. *  <tr valign="top"  align="left"> *      <td><b><code>text</code></b> *      <td>All buttons *      <td><code>NAME</code> *      <td>If you do not want the text of the button to mirror that *          of the <code>Action</code>, set the property *          <code>hideActionText</code> to <code>true</code>.  If *          <code>hideActionText</code> is <code>true</code>, setting the *          <code>Action</code> changes the text of the button to *          <code>null</code> and any changes to <code>NAME</code> *          are ignored.  <code>hideActionText</code> is useful for *          tool bar buttons that typically only show an <code>Icon</code>. *          <code>JToolBar.add(Action)</code> sets the property to *          <code>true</code> if the <code>Action</code> has a *          non-<code>null</code> value for <code>LARGE_ICON_KEY</code> or *          <code>SMALL_ICON</code>. *  <tr valign="top"  align="left"> *      <td><b><code>displayedMnemonicIndex</code></b> *      <td>All buttons *      <td><code>DISPLAYED_MNEMONIC_INDEX_KEY</code> *      <td>If the value of <code>DISPLAYED_MNEMONIC_INDEX_KEY</code> is *          beyond the bounds of the text, it is ignored.  When *          <code>setAction</code> is called, if the value from the *          <code>Action</code> is <code>null</code>, the displayed *          mnemonic index is not updated.  In any subsequent changes to *          <code>DISPLAYED_MNEMONIC_INDEX_KEY</code>, <code>null</code> *          is treated as -1. *  <tr valign="top"  align="left"> *      <td><b><code>icon</code></b> *      <td>All buttons except of <code>JCheckBox</code>, *      <code>JToggleButton</code> and <code>JRadioButton</code>. *      <td>either <code>LARGE_ICON_KEY</code> or *          <code>SMALL_ICON</code> *     <td>The <code>JMenuItem</code> subclasses only use *         <code>SMALL_ICON</code>.  All other buttons will use *         <code>LARGE_ICON_KEY</code>; if the value is <code>null</code> they *         use <code>SMALL_ICON</code>. *  <tr valign="top"  align="left"> *      <td><b><code>accelerator</code></b> *      <td>All <code>JMenuItem</code> subclasses, with the exception of *          <code>JMenu</code>. *      <td><code>ACCELERATOR_KEY</code> *      <td>&nbsp; *  <tr valign="top"  align="left"> *      <td><b><code>selected</code></b> *      <td><code>JToggleButton</code>, <code>JCheckBox</code>, *          <code>JRadioButton</code>, <code>JCheckBoxMenuItem</code> and *          <code>JRadioButtonMenuItem</code> *      <td><code>SELECTED_KEY</code> *      <td>Components that honor this property only use *          the value if it is {@code non-null}. For example, if *          you set an {@code Action} that has a {@code null} *          value for {@code SELECTED_KEY} on a {@code JToggleButton}, the *          {@code JToggleButton} will not update it's selected state in *          any way. Similarly, any time the {@code JToggleButton}'s *          selected state changes it will only set the value back on *          the {@code Action} if the {@code Action} has a {@code non-null} *          value for {@code SELECTED_KEY}. *          <br> *          Components that honor this property keep their selected state *          in sync with this property. When the same {@code Action} is used *          with multiple components, all the components keep their selected *          state in sync with this property. Mutually exclusive *          buttons, such as {@code JToggleButton}s in a {@code ButtonGroup}, *          force only one of the buttons to be selected. As such, do not *          use the same {@code Action} that defines a value for the *          {@code SELECTED_KEY} property with multiple mutually *          exclusive buttons. * </table> * <p> * <code>JPopupMenu</code>, <code>JToolBar</code> and <code>JMenu</code> * all provide convenience methods for creating a component and setting the * <code>Action</code> on the corresponding component.  Refer to each of * these classes for more information. * <p> * <code>Action</code> uses <code>PropertyChangeListener</code> to * inform listeners the <code>Action</code> has changed.  The beans * specification indicates that a <code>null</code> property name can * be used to indicate multiple values have changed.  By default Swing * components that take an <code>Action</code> do not handle such a * change.  To indicate that Swing should treat <code>null</code> * according to the beans specification set the system property * <code>swing.actions.reconfigureOnNull</code> to the <code>String</code> * value <code>true</code>. * * @author Georges Saab * @see AbstractAction */public interface Action extends ActionListener {    /**     * Useful constants that can be used as the storage-retrieval key     * when setting or getting one of this object's properties (text     * or icon).     */    /**     * Not currently used.     */    public static final String DEFAULT = "Default";    /**     * The key used for storing the <code>String</code> name     * for the action, used for a menu or button.     */    public static final String NAME = "Name";    /**     * The key used for storing a short <code>String</code>     * description for the action, used for tooltip text.     */    public static final String SHORT_DESCRIPTION = "ShortDescription";    /**     * The key used for storing a longer <code>String</code>     * description for the action, could be used for context-sensitive help.     */    public static final String LONG_DESCRIPTION = "LongDescription";    /**     * The key used for storing a small <code>Icon</code>, such     * as <code>ImageIcon</code>.  This is typically used with     * menus such as <code>JMenuItem</code>.     * <p>     * If the same <code>Action</code> is used with menus and buttons you'll     * typically specify both a <code>SMALL_ICON</code> and a     * <code>LARGE_ICON_KEY</code>.  The menu will use the     * <code>SMALL_ICON</code> and the button will use the     * <code>LARGE_ICON_KEY</code>.     */    public static final String SMALL_ICON = "SmallIcon";     /**     * The key used to determine the command <code>String</code> for the     * <code>ActionEvent</code> that will be created when an     * <code>Action</code> is going to be notified as the result of     * residing in a <code>Keymap</code> associated with a     * <code>JComponent</code>.     */    public static final String ACTION_COMMAND_KEY = "ActionCommandKey";     /**     * The key used for storing a <code>KeyStroke</code> to be used as the     * accelerator for the action.     *     * @since 1.3     */    public static final String ACCELERATOR_KEY="AcceleratorKey";     /**     * The key used for storing an <code>Integer</code> that corresponds to     * one of the <code>KeyEvent</code> key codes.  The value is     * commonly used to specify a mnemonic.  For example:     * <code>myAction.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_A)</code>     * sets the mnemonic of <code>myAction</code> to 'a', while     * <code>myAction.putValue(Action.MNEMONIC_KEY, KeyEvent.getExtendedKeyCodeForChar('\u0444'))</code>     * sets the mnemonic of <code>myAction</code> to Cyrillic letter "Ef".     *     * @since 1.3     */    public static final String MNEMONIC_KEY="MnemonicKey";     /**     * The key used for storing a <code>Boolean</code> that corresponds     * to the selected state.  This is typically used only for components     * that have a meaningful selection state.  For example,     * <code>JRadioButton</code> and <code>JCheckBox</code> make use of     * this but instances of <code>JMenu</code> don't.     * <p>     * This property differs from the others in that it is both read     * by the component and set by the component.  For example,     * if an <code>Action</code> is attached to a <code>JCheckBox</code>     * the selected state of the <code>JCheckBox</code> will be set from     * that of the <code>Action</code>.  If the user clicks on the     * <code>JCheckBox</code> the selected state of the <code>JCheckBox</code>     * <b>and</b> the <code>Action</code> will <b>both</b> be updated.     * <p>     * Note: the value of this field is prefixed with 'Swing' to     * avoid possible collisions with existing <code>Actions</code>.     *     * @since 1.6     */    public static final String SELECTED_KEY = "SwingSelectedKey";     /**     * The key used for storing an <code>Integer</code> that corresponds     * to the index in the text (identified by the <code>NAME</code>     * property) that the decoration for a mnemonic should be rendered at.  If     * the value of this property is greater than or equal to the length of     * the text, it will treated as -1.     * <p>     * Note: the value of this field is prefixed with 'Swing' to     * avoid possible collisions with existing <code>Actions</code>.     *     * @see AbstractButton#setDisplayedMnemonicIndex     * @since 1.6     */    public static final String DISPLAYED_MNEMONIC_INDEX_KEY =                                 "SwingDisplayedMnemonicIndexKey";     /**     * The key used for storing an <code>Icon</code>.  This is typically     * used by buttons, such as <code>JButton</code> and     * <code>JToggleButton</code>.     * <p>     * If the same <code>Action</code> is used with menus and buttons you'll     * typically specify both a <code>SMALL_ICON</code> and a     * <code>LARGE_ICON_KEY</code>.  The menu will use the     * <code>SMALL_ICON</code> and the button the <code>LARGE_ICON_KEY</code>.     * <p>     * Note: the value of this field is prefixed with 'Swing' to     * avoid possible collisions with existing <code>Actions</code>.     *     * @since 1.6     */    public static final String LARGE_ICON_KEY = "SwingLargeIconKey";     /**     * Gets one of this object's properties     * using the associated key.     * @see #putValue     */    public Object getValue(String key);    /**     * Sets one of this object's properties     * using the associated key. If the value has     * changed, a <code>PropertyChangeEvent</code> is sent     * to listeners.     *     * @param key    a <code>String</code> containing the key     * @param value  an <code>Object</code> value     */    public void putValue(String key, Object value);     /**     * Sets the enabled state of the <code>Action</code>.  When enabled,     * any component associated with this object is active and     * able to fire this object's <code>actionPerformed</code> method.     * If the value has changed, a <code>PropertyChangeEvent</code> is sent     * to listeners.     *     * @param  b true to enable this <code>Action</code>, false to disable it     */    public void setEnabled(boolean b);    /**     * Returns the enabled state of the <code>Action</code>. When enabled,     * any component associated with this object is active and     * able to fire this object's <code>actionPerformed</code> method.     *     * @return true if this <code>Action</code> is enabled     */    public boolean isEnabled();     /**     * Adds a <code>PropertyChange</code> listener. Containers and attached     * components use these methods to register interest in this     * <code>Action</code> object. When its enabled state or other property     * changes, the registered listeners are informed of the change.     *     * @param listener  a <code>PropertyChangeListener</code> object     */    public void addPropertyChangeListener(PropertyChangeListener listener);    /**     * Removes a <code>PropertyChange</code> listener.     *     * @param listener  a <code>PropertyChangeListener</code> object     * @see #addPropertyChangeListener     */    public void removePropertyChangeListener(PropertyChangeListener listener); }