[techjuice]

Build it and see how it goes. Ideas are nice to have, but of little to no value until you start to implement it to see if it is actually of value.

First step is to learn how to develop android apps.

Read all of this developmenthttps://developer.android.com/training/basics/firstapp/

Learn about Google Maps https://developers.google.com/maps/documentation/android-sdk...

Learn about integrating with facebook https://developers.facebook.com/docs/android/getting-started...

While you are at it make sure you have a decent android device so you can test on hardware. Once you have put the time in to test your idea (40-100hours) you should have a pretty good idea if you want to continue with it. Just because there are ideas and apps that do this does not mean you cannot build something better or more streamlined.