public abstract class FocusAdapter
An abstract adapter class for receiving keyboard focus events.
The methods in this class are empty. This class exists as
convenience for creating listener objects.
Extend this class to create a FocusEvent listener
and override the methods for the events of interest. (If you implement the
FocusListener interface, you have to define all of
the methods in it. This abstract class defines null methods for them
all, so you can only have to define methods for events you care about.)
Create a listener object using the extended class and then register it with
a component using the component's addFocusListener
method. When the component gains or loses the keyboard focus,
the relevant method in the listener object is invoked,
and the FocusEvent is passed to it.