You should take a look at this tutorial , it is very comprehensive, and the stackoverflow format is not intended for long tutorials.
Typically, Google provides a library for using Google Maps in your MapView application. Source code for an example is available here .
UPDATE: based on the comments below, and now that I understand the question better, the answer is that you cannot call code or reuse code from one application to another in android. The only official way is to use Intent to invoke the entire Activity. (Here's another thread on the topic .)