All Packages  Class Hierarchy  This Package  Previous  Next  Index

Interface java.awt.swing.Action

public interface Action
extends ActionListener

The JFC Action interface defines a fundamental unit of a program's operation. This interface allows different components to access the same functionality, which can be enabled or disabled in a single step.

In addition to the actionPerformed method defined by the ActionListener interface, this interface allows the application to define, in a single place:

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.
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.
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.

Containers in the Swing set like menus and toolbars know how to add an Action object, as well as other components, using a version of the add method. When an Action object is added to such a container, the container:

Creates a component that is appropriate for that container (a toolbar creates a button component, for example).
Gets the appropriate property(s) from the Action object to customize the component (for example, the icon image and flyover text).
Checks the intial state of the Action object to determine if it is enabled or disabled, and renders the component in the appropriate fashion.
Registers a listener with the Action object so that is notified of state changes. When the Action object changes from enabled to disabled, or back, the container makes the appropriate revisions to the event-generation mechanisms and renders the component accordingly.

For example, both a menu item and a toolbar button could access a Cut action object. The text associated with the object is specified as "Cut", and an image depicting a pair of scissors is specified as its icon. The Cut action-object can then be added to a menu and to a toolbar. Each container does the appropriate things with the object, and invokes its actionPerformed method when the component associated with it is activated. The application can then disable or enable the application object without worrying about what user-interface components are connected to it.

...REVISIT...SUBJECT TO CHANGE........................................... Applications can also define and use Action objects and attach them to an existing component, rather than adding them to an Action-aware container. For example, a JButton can be attached to an Action object using the JButton's addActionListener method. The result is the same as if the button were in an Action-aware container -- the button listens and responds to the Action-objects state and customizes itself using the Action-object's properties. ...END REVISIT............................................................

This interface can be added to an existing class or used to create an adapter (typically, by subclassing AbstractAction). The Action object can then be added to multiple action-aware containers and connected to Action-capable components. The GUI controls can then be activated or deactivated all at once by invoking the Action object's setEnabled method.

See Also:: AbstractAction

DEFAULT: Useful constants that can be used as the storage-retreival key when setting or getting one of this object's properties (text or icon).
LONG_DESCRIPTION
NAME
SHORT_DESCRIPTION
SMALL_ICON

addPropertyChangeListener(PropertyChangeListener): Add or remove a PropertyChange listener.
getIcon(String): Sets/gets one of this object's icons, using the associated key.
getText(String): Sets/gets one of this object's description-Strings, using the associated key.
isEnabled()
removePropertyChangeListener(PropertyChangeListener)
setEnabled(boolean): Sets/tests the enabled state of the Action.
setIcon(String, Icon)
setText(String, String)

DEFAULT

public static final String DEFAULT

Useful constants that can be used as the storage-retreival key when setting or getting one of this object's properties (text or icon).

NAME

public static final String NAME

SHORT_DESCRIPTION

public static final String SHORT_DESCRIPTION

LONG_DESCRIPTION

public static final String LONG_DESCRIPTION

SMALL_ICON

public static final String SMALL_ICON

getText

public abstract String getText(String key)

Sets/gets one of this object's description-Strings, using the associated key.

setText

public abstract void setText(String key,
                             String text)

getIcon

public abstract Icon getIcon(String key)

Sets/gets one of this object's icons, using the associated key.

setIcon

public abstract void setIcon(String key,
                             Icon g)

setEnabled

public abstract void setEnabled(boolean b)

Sets/tests the enabled state of the Action. When enabled, any component associated with this object is active and able to fire this object's actionPerformed method.

isEnabled

public abstract boolean isEnabled()

addPropertyChangeListener

public abstract void addPropertyChangeListener(PropertyChangeListener listener)

Add or remove a PropertyChange listener. Containers and attached components use these methods to register interest in this Action object. When its state changes from enabled to disabled, or back, the registered listeners are informed of the change.

removePropertyChangeListener

public abstract void removePropertyChangeListener(PropertyChangeListener listener)

All Packages  Class Hierarchy  This Package  Previous  Next  Index

Submit a bug or feature