Add Google map function to my Android App

I have an android app that works fine, however the coder did not put in the google mapping function I needed. The app retrieves a file from my server, which has the GPS in it. I need it to take the GPS coordinates from the file and then use that to map out directions for the user to travel to that location provided in the file. There are no other changes that need to be made. The new code then needs to be packaged into a APK file. Final deliverable will be: New source code New APK file