Help writing a simple app in android studio?

Question

Java

Make a messenger in one direction (not online and you don’t need to answer anyone) (roughly speaking, I entered the text, and it displays it in textview. And there will be a lot of textview)
Messages are saved on the phone. Where to start writing? how to save messages

Answer 1

look at firebase db

Answer 2

See using NoSQL in Android or use the built-in database in Android.