Log a user in using a generated Anonymous Login ID

Question

I am writing an Android application and I am trying to log users in anonymously so they don't have to go through any sort of registration process. I am storing their anonymous user ID in shared preferences, and when the application opens, I am trying to log them in based on that user ID. I am trying to figure out the correct way to do this, as there doesn't seem to be an auth function that just takes in a UID. Currently I have it using auth(), but I don't feel like that is correct.

Here is some sample code:

String userID = getUserID();

    if(userID.equals("NOT_FOUND")) {
        ref.authAnonymously(new Firebase.AuthResultHandler() {
            @Override
            public void onAuthenticated(AuthData authData) {
                //successful authentication
                //save auth data
                SharedPreferences prefs = getSharedPreferences(
                        "USER_ID", Context.MODE_PRIVATE);
                String id = authData.getUid();
                prefs.edit().putString("USER_ID", id).commit();
            }

            @Override
            public void onAuthenticationError(FirebaseError firebaseError) {
                //unsuccessful authentication
            }
        });
    } else {
        ref.auth(userID, new Firebase.AuthListener() {
           ...

Answer 1

You're creating a new authentication session each and every time you invoke FirebaseRef.authAnonymously(...). This method only needs to be invoked once, after which the user will authenticated upon page refreshes. Also note that you do not need to call FirebaseRef.auth() again once restarting the application, as that piece is automatically handled for you.

If you'd like to check for the current authentication state of the user, and only then create a new authentication session if the user is not currently authenticated, use the synchronous accessor for authentication state FirebaseRef.getAuth().

Lastly, once you create an anonymous authentication session, no new sessions may ever be created with the same uid. That session will live until your predefined session expiration time (configured in your account dashboard) or until your user logs out, after which that uid is permanently retired.