How to correctly switch the UI state within the same Activity?

Question

Android

There is an Activity in which there are about five UI states, depending on which individual UI elements are shown and animations are started. In addition, not every state can be switched to another. In general, FSM in its purest form.
Question: how to implement it correctly for Android (4+)? Whether there are standard means, or sensible library? Googling didn't turn up anything meaningful.

Answer 1

Using fragments should help.