Java Reference
In-Depth Information
);
gui.add(b);
Action events
come from the basic action on the component, such as
pressing a button or selecting a check box. The
ActionEvent
class has de-
tails of an action event, such as the keyboard modifiers (such as the Alt
or Control key) that were being pressed when the action occurred. To
receive this event you must register interest in action events, either by
adding an
ActionListener
to the component as shown here or by invok-
ing
enableEvents
with an appropriate mask.
The
ActionListener
interface in the previous example is a
listener in-
terface.
Listener interfaces extend
java.util.EventListener
and exist for
many kinds of events: mouse, keyboard, window, item, text, container,
and general component events. You use objects that implement listener
interfaces to trigger method execution when events occurall of which get
executed by the event thread. When an event occurs, the component's
processEvent
method is called, which in turn calls
processXXXEvent
for the
specific event, and that in turn will call the
XXXOccurred
method of all re-
gistered listeners for that event.
Other classes in
java.awt
allow you to set colors, fonts, and so on. All
these properties are inherited by default from outer componentsthe de-
fault colors of a button are those of the frame in which it has been
placed. You can override this setting at any level by explicitly specifying
a color for a component. That component and all its contained compon-
ents will change to the specified color unless a subcomponent has its
color specified.
Various subpackages of
java.awt
allow you to manipulate images,
sounds, and other media:
•
java.awt.color
color manipulation tools
•
java.awt.datatransfer
moving data between applications, such as
with cut, copy, and paste
