So your login screen has an email address field? It’s easy to save your users some typing by auto-completing email addresses from Android’s account manager.
Firstly, ask for the
GET_ACCOUNTS permission in
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
This snippet queries the account manager for Google accounts (almost every user has at least one) and puts those email addresses in an
The only thing left to do is change the
EditText to an
AutoCompleteTextView and call
setAdapter(getEmailAddressAdapter(context)) on that
You might also consider simply setting the text of the email field when there is a single email address in the account manager.