Android :: Using New Sdk Methods On Devices Running Older Sdks

I'm using the level 5 sdk to compile my app, but set my target to sdk level 3 in my manifest. All is fine.

I may need to use some level 5 classes (ExifInterface) though. What's the right way to go about using them while not fouling things up for devices running older sdk versions? Do we simply restrict use of the newer API methods to completely separate class files? Something like this:

CODE:.................

so as long as the api methods are completely separated into files that the older devices won't invoke, we should be ok?