protected/private - why bother? [duplicate]

Question

DUPE: Private vs. Public members in practice (how important is encapsulation?)

In the course of writing a program in Java, I have abstracted out some libraries that I can see a possible use for in future projects.

Why should I bother with setting restricted access (private/protected) on any of these methods?

It seems like this will just make my life more complicated in the future. If I use public on everything, I will never need to worry about whether I can call something from some other class. I have never seen a case in any of my code yet where it made any sense for me to use anything except public.

Is it so wrong to use 'public' on everything? Am I going to be struck down by the Java gods?

Answer 1

Yes, it's wrong to use public on everything. It means you have absolutely no concept of the difference between "this member is part of a public API; you're expected to be able to use it from the outside world, and it shouldn't change" and "this member is an implementation detail. If I want to change it later, I can do so because I know nothing from the outside world will be calling it."

Having a clear split between API and implementation is important for flexibility and clarity IMO.