Overriding refers to the re-definition of a method in a subclass which
would otherwise have been inherited from its superclass. There
are two varieties of overriding possible in Java:
Total (complete) overriding
No reference is made to superclass' definition of the method
at all.
Partial overriding
The subclass method makes a call to its superclass definition,
through the "super" reference.
There is sample code in the lecture code repository.