Protect API URL access via hash in Android app

Question

In my Android application, the user can submit content to the database which can then be seen by all the other users as well.

This new content is sent to the server

Answer 1

Use SSL (HTTPS) for your data transfers. The exchange is encrypted before any data is sent, so anyone listening in won't be able to see either the URL or data that is sent to the server. To verify this for yourself, install Wireshark on your dev system and load the URL into a browser. You'll not see any data in the clear (either the URL or the data that is sent via either GET or POST).