How Does The Firebase Authstatelistener Work?

I am developing an android app using firebase for user management and authentication. I was wondering when the auth state listener gets called and how it works, as in my app I have

Solution 1:

As the Firebase API says:

AuthStateListener is called when there is a change in the authentication state.

OnAuthStateChanged gets invoked in the UI thread on changes in the authentication state:

• Right after the listener has been registered
• When a user is signed in
• When the current user is signed out
• When the current user changes
• When there is a change in the current user's token (Notice this has been removed and moved to a separate listener, see FirebaseAuth.IdTokenListener)