How to use a CiviCRM generated form in an Android App
You might want to check the CiviMobile Extension:

https://civicrm.org/extensions/civimobile

and see how things are done in that app. Might help give you a better direction for the app.

In general, you might want to first design / develop what you want to do with CiviCRM first before deciding how to do it in an app. Your use case seems to be an instance of CiviCRM profiles.