I'm working on Android application using Google Maps APIs that other person created. Project have different modules like client, client_developer, client_preproduction etc. but they all share core code in other module.
I can't understand why in google_maps_api.xml he have different API keys "debug key", "release key", "test key".
Why would he do that if you need only one key for APIs work?
You need to sign your app with the digital fingerprint SHA-1: Android SDK Tools generate differrent certificates depending on your purposes i.e. If you need to test your app, generate a debug certificate, or if you want to publish your app, generate a launch certificate to put it on google play. You could read more here: https://developers.google.com/maps/documentation/android-api/signup
Hope it helps! :)