/*
* @(#)Action.java 1.36 06/04/18
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
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>
* <tr valign="top" align="left">
* <td><b><code>toolTipText</code></b>
* <td>All
* <td><code>SHORT_DESCRIPTION</code>
* <td>
* <tr valign="top" align="left">
* <td><b><code>actionCommand</code></b>
* <td>All
* <td><code>ACTION_COMMAND_KEY</code>
* <td>
* <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>
* <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>.
*
* @version 1.36 04/18/06
* @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'.
*
* @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);
}
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