Firebase same account on multiple android devices prevention

Question

I want the users of my app to sign in through a single device only at the same time. How do I achieve this?

Answer 1

You may add device id in Firebase on register and check it on login. You can get the device id as follows:

private String android_id = Secure.getString(
    getContext().getContentResolver(), Secure.ANDROID_ID
);

Or you can browse here.