Solutions - Design Patterns Java - page 282

For example, a class that implements the MouseMotionListener interface from
java.awt.event must implement the methods:
public void mouseDragged(MouseEvent e)
public void mouseMoved(MouseEvent e)
The presence of these methods does not imply that the methods will take an action when a
client calls them. In fact, it would not be uncommon to react to the mouseDragged()
method but to ignore to calls to the mouseMoved() method.
SOLUTION 2.4
A class that implements WindowListener must implement all the methods the interface
declares, even if the class will ignore these methods when called. The WindowAdapter class
ignores all the methods in Window-Listener. This lets a subclass implement only the methods
that it wants to react to, as Figure B.1 shows. The anonymous class in Figure B.1 can react to
only the windowClosing() event, without having to implement dummy methods for the
other methods specified in the WindowListener interface.