Remember that an interface is a kind of contract that must be implemented by a concrete ... a Java code challenge. We have the code challenge below, or you can view the abstract classes vs.

Should I use an abstract class or an interface? Abstract classes provide you the flexibility to have certain concrete methods and some other methods that the derived classes should implement.

protected and private concrete methods, while interfaces have all fields as automatically public, static and final. Interfaces, however, support multiple inheritances where abstract classes don't.