Congratulations! You are now the proud author of a pet store inventory suite. Now that you have all the major features of the pet store software implemented, it's time to add some extra features. You're on your own; think of some features that you think a pet store should have, or just explore the features of JDO.
Here are a couple of suggestions to get you started:
Modify Animal to contain an inventory cost and a resale price. Calculate the real dollar amount eaten by the snakes (the sum of the inventory costs of all the consumed rabbits), and the cost assuming that all the eaten rabbits would have been sold had they been alive. Ignore the fact that the rabbits, had they lived, would have created more rabbits, and the implications of the reduced food costs due to the not-quite-as-hungry snakes and the smaller number of rabbits.
Modify Dog to have a many-to-many relation to a new class called Breed, which contains a name identifying the breed of the dog and a description of the breed. Put together an admin tool for breeds and for associating dogs and breeds.