Is there any reason for an empty concrete method in an abstract class?

Question

I was recently looking through some open source code PicketLink code. If you take a look at this class, you\'ll see a number of concrete methods in an abstract class that d

Answer 1

Building off of Andres Fortier's answer, you will also see this pattern a lot in Swing, with the various EventListener Adapter classes. For example, MouseAdapter provides corresponding empty methods for each listener method. This allows the interface to define all relevant methods, but implementations to extend the corresponding adapter and only override a single method they care about, instead of being forced to provide empty bodies for all other interface methods.