Taking advantage of the multiple inheritance of interfaces

Java 9 doesn't allow us to declare a class with multiple superclasses or base classes, so there is no support for multiple inheritance of classes. A subclass can inherit from just one class. However, a class can implement one or more interfaces. In addition, we can declare classes that inherit from a superclass and implement one or more interfaces. Hence, we can combine class-based inheritance with the implementation of interfaces.

We want the WonderCat class to implement both the DrawableInComic and DrawableInGame interfaces. We want to be able to use any WonderCat instance as both a comic character and a game character. In order to do so, we must change the class declaration and add the DrawableInGame interface to the list of interfaces that the class implements and declare all the methods included in this added interface within the class.

The following lines show the new class declaration that specifies that the WonderCat class...