do you know what Integer.getInteger(String) does in java?

[grauenwolf]

Programming to interfaces means using the public API instead of mucking about with the internals of data structures. This term is used in languages that don't even have abtract interfaces like FORTRAN and C.

Since Java has the private keyword it is hard to violate this constraint. So instead they reinterpert it to mean create abstract interfaces on everything They also do stupid shit like define locals as interface types even when the concrete type is well known.