hierarchy : Java Glossary
- Tree structured hierarchies appear frequently in coding, e.g. countries, states,
counties, cities. I have found the best way to write such code is for a Country class
to have methods that only deal with the country as a whole. It can have methods that
deal with all the states or some subset of them, but the code to write these must never
use the State fields. It must be written in terms of the State methods. Don’t
ever attempt to write code that spans several levels of the hierarchy. Just write code
at each level that fobs the work off on the methods of one level down.