The listener interface for receiving
WindowEvents
, including
WINDOW_GAINED_FOCUS
and
WINDOW_LOST_FOCUS
events.
The class that is interested in processing a
WindowEvent
either implements this interface (and
all the methods it contains) or extends the abstract
WindowAdapter
class (overriding only the methods of interest).
The listener object created from that class is then registered with a
Window
using the
Window
's
addWindowFocusListener
method.
When the
Window
's
status changes by virtue of it being opened, closed, activated, deactivated,
iconified, or deiconified, or by focus being transfered into or out of the
Window
, the relevant method in the listener object is invoked,
and the
WindowEvent
is passed to it.