Which is the best GUI designer for android apps which you have coded in Java?

Answer 1

Xml

Answer 2

Yes I can give you the steps first define the design on a wire frame then create ui starting from edit fields then define a list view in which texts will be fetched in then follow by menu which holds details like settings and profile edit with each having its own activity. Then come to the code part in which you'll declare views used then create an async task class for threading and sync with db then work on caching aspects. Don't worry of how it'll work on real time aspects. Google has a solution that is firebase and it'll handle push notifications and real time chatting. I did a prototype for chat app. For phone number verification their is fabric.io