Get other user locations

we are developing an android application for our thesis

my questions:

1) how could we make the application detect other users that are using the app? 2) how co开发者_StackOverflow中文版uld we display the location of the users on the map?

Can anyone give us necessary codes?

we would be very thankful thanks :D

1. I suggest asking for the user's data on a welcome screen in order to use the app.
2. By sending the location of the users, storing it in a DB, and then allow each user to get a Map with those geopoints. You'll need a Cache on some point.