Exit classes at compile time

I am developing an application in the native Android application layer.

I originally developed it for ICS, but now I must also transfer the same code base to GingerBread.

During the implementation of ICS, I used hidden ICS classes, but these classes are not present in GingerBread.

I want to keep the same code base for both versions (ICS and GingerBread).

Is there a way in which I can leave several classes when compiling the source code for GingerBread and turn them on when I need it for ICS?