order of testing instances

Your inheritance hierarchy is eg. Animal -> Cat -> Lion means a Lion is a Cat is an Animal If you now have a Lion object and test if it is an Animal than this will be true. If you test for Cat or Lion then these both test will evaluate to true as well. The task however asks you to just output one result and that should be as specific as possible. That's why you should work with if - else if Here of course you start with the more specific classes like Lion and Tiger. If it is none of these classes you check for Cat and last but not least the Animal class. Another possibility would be smth like:

if (o instanceof Cat || o instanceof Bull || o instanceof Cow)
    return o.getClass().getSimpleName();

return "Animal";

If the object is a Cat or a descendant of Cat or a Bull or a Cow, then return a String representation of the class name. Otherwise return Animal