A good answer might be:

Yes. You might wonder that it does not extend a base class, but it does. If no other class is extended, Object is the base class. SmallClass extends Object and implements InterfaceA.

Example Problem

Let us create a database program for a store. The store sells:

Of these goods, toys and books are taxable, but food is not. There are many other things that are taxable, such as services or entertainment so we want to have the concept "taxable" as a separate concept, not part of the concept of Goods.

Here is what the concept Taxable looks like:

When implemented in Java, these concepts will appear as classes and an interface.

QUESTION 5:

(Design question: ) Decide on an implementation for each concept:

ConceptParent Class, Child Class, or Interface?
Goods
Food
Toy
Book
Taxable