What will be the OOP approach? (or YOUR approach?)

Question

I'm having difficulties with some general OOP & Java approach. There are various ways to let classes/objects communicate with each other. To give a simple example:

• I need object A to perform action X.
• Object A needs P, Q and R to perform this action X.

Will then Object A retrieve P, Q and R by itself (within action X), or must these values be parameters for action X?

Answer 1

This is too general a question to be answered concretely. Either approach can be good in certain situations. Some factors:

• passing P, Q and R as parameters makes A easier to reuse and test (see Dependency Injection)
• if P, Q and R are not used anywhere else outside A, they could be made method local
• if P, Q and R are also used in other methods of A, they could be made members