Before we start writing code, let's create a very basic class diagram that shows how we would design the Animal class hierarchy. I usually start off by doing a very basic diagram that simply shows the classes themselves without much detail. This helps me picture the class hierarchy in my mind. The following diagram shows the class hierarchy for our object-oriented design:
This diagram shows that we have one superclass named Animal and two subclasses named Alligator and Lion. We may think that, with the three categories (land, air, and sea), we would want to create a larger class hierarchy where the middle layer would contain the classes for the land, air, and sea animals. This would allow us to separate the code for each category; however it is not possible with our requirements. The reason this is not possible is that any of the animal types can be members of multiple categories and with a class hierarchy each class can have one and only one superclass. This means...