Java Reference
In-Depth Information
class forward key method calls to it. The
Component
class in
java.awt
uses this approach,
although it uses a
PropertyChangeSupport
object instead of an
Observable
object.
The
PropertyChangeSupport
class is quite similar to the
Observable
class but is part
of the
java.beans
package. The JavaBeans API exists to support the creation of reusable
components. This API has found its greatest applicability to GUI components, but you can
certainly apply it elsewhere. The
Component
class uses a
PropertyChangeSupport
object to let interested observers register for notification of changes in the properties of labels,
panels, and other GUI components. Figure 9.6 shows the relationship between
the
Component
class from
java.awt
and the
PropertyChangeSupport
class.
Figure 9.6. A
Component
object maintains a
PropertyChangeSupport
object that
maintains a collection of listeners.
The
Component
class duplicates part of the interface of the
Prop-ertyChangeSupport
class. These methods in
Component
each forward the message call to an instance of
the
PropertyChangeSupport
class.
