Android™ How to Program, Second Edition

I.8. Adapter Classes

Many event-listener interfaces, such as MouseListener and MouseMotionListener, contain multiple methods. It’s not always desirable to declare every method in an event-listener interface. For instance, an app may need only the mouseClicked handler from MouseListener or the mouseDragged handler from MouseMotionListener. Interface WindowListener specifies seven window event-handling methods. For many of the listener interfaces that have multiple methods, packages java.awt.event and javax.swing.event provide event-listener adapter classes. An adapter class implements an interface and provides a default implementation (with an empty method body) of each method in the interface. You can extend an adapter class to inherit the default ...