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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.

 * <br>

 *

 * <h3><a name="buttonActions"></a>Swing Components Supporting <code>Action</code></h3>

 * <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>.

 *

 * <table border="1" cellpadding="1" cellspacing="0"

 *         summary="Supported Action properties">

 *  <tr valign="top"  align="left">

 *    <th style="background-color:#CCCCFF" align="left">Component Property

 *    <th style="background-color:#CCCCFF" align="left">Components

 *    <th style="background-color:#CCCCFF" align="left">Action Key

 *    <th style="background-color:#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);

}