Java Reference
In-Depth Information
Figure 6.1
The primary classes in the AWT hierarchy.
6.2 AWT
The AWT (Abstract Windowing Toolkit) package (
java.awt
) and sub-packages
came with Java 1.0 and still provide the essential set of classes for all Java graphics.
Even Swing builds on the graphics base in AWT. The diagram in Figure 6.1 shows
the primary members of the AWT class hierarchy.
The key
Component
class provides the base class for all the AWT visual
components and also for the Swing components. This class contains a very large
number of public methods (see the Java API description for
Component
) that
provide access to and control of attributes of a visual component such as its
position, size, colors, and so forth. Subclasses of
Component
can override some
of these methods and also include new methods to deal with the specific features
of the new type of component.
Another very important class,
Container
,which is itself a subclass of
Component
, provides for holding instances of other components. The
Window
subclass of
Container
, for example, provides for the
top-level
visible containers
Frame
and
Dialog
that usually hold multiple visible components.
Containers can also hold other containers. The
Panel
class, in particular, is
used within a top-level container to hold and arrange its sub-components, which
often are also panels. An elaborate GUI display typically employs several panels
to arrange the visible
atomic
(non-container) components such as labels, buttons,
Search WWH ::
Custom Search