Provide sign-in hints to a user

Requests to retrieve user credentials can fail when a user has not yet saved credentials or when a user has not yet signed up to your app. In these situations, use the Credentials API to retrieve sign-in hints, such as the user's name and email address. Use these hints to pre-fill your app's sign-in and sign-up forms, speeding up your app's on-boarding process.

On Android 6.0 (Marshmallow) and newer, your app does not need to request any device or runtime permissions to retrieve sign-in hints with the Credentials API.

Before you begin

Configure an Android Studio project.

Retrieve sign-in hints

To retrieve the sign-in hints, first configure the hint selector dialog by creating a HintRequest object. Then, pass the HintRequest object to Auth.CredentialsApi.getHintPickerIntent() to get an intent to prompt the user to choose an email address. Finally, start the intent with startIntentSenderForResult().

HintRequest hintRequest = new HintRequest.Builder()
        .setHintPickerConfig(new CredentialPickerConfig.Builder()
                .setShowCancelButton(true)
                .build())
        .setEmailAddressIdentifierSupported(true)
        .setAccountTypes(IdentityProviders.GOOGLE)
        .build();

PendingIntent intent =
        Auth.CredentialsApi.getHintPickerIntent(mCredentialsClient, hintRequest);
try {
    startIntentSenderForResult(intent.getIntentSender(), RC_HINT, null, 0, 0, 0);
} catch (IntentSender.SendIntentException e) {
    Log.e(TAG, "Could not start hint picker Intent", e);
}

Smart Lock sign-in hint chooser

The user is prompted to choose an email address to use.

Then, in the activity's onActivityResult() method, retrieve the hints from the Credential.EXTRA_KEY parcel, check whether the user is in your user database, and start the appropriate activity with the credentials hint.

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == RC_HINT) {
        if (resultCode == RESULT_OK) {
            Credential credential = data.getParcelableExtra(Credential.EXTRA_KEY);
            Intent intent;
            // Check for the user ID in your user database.
            if (userDatabaseContains(credential.getId())) {
                intent = new Intent(this, SignInActivity.class);
            } else {
                intent = new Intent(this, SignUpNewUserActivity.class);
            }
            intent.putExtra("com.mycompany.myapp.SIGNIN_HINTS", credential);
            startActivity(intent);
        } else {
            Log.e(TAG, "Hint Read: NOT OK");
            Toast.makeText(this, "Hint Read Failed", Toast.LENGTH_SHORT).show();
        }
    }

    ...

}

Pre-fill the sign-in form

If the user is in your user database and you started your app's sign-in activity, you can (optionally) check if the Credential object contains an ID token. If so, you can sign in the user with the ID token, without requiring the user to type a password.

If the Credential object doesn't contain an ID token (or you don't want to use the ID token), pre-fill the sign-in fields with the hints that you added to the intent.

public class SignInActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Intent intent = getIntent();
        Credential credential = intent.getParcelableExtra("com.mycompany.myapp.SIGNIN_HINTS");

        // Pre-fill ID field
        mUsernameView.setText(credential.getId());

        ...
    }

    ...
}

Pre-fill the sign-up form

If the user isn't in your user database and you started your app's sign-up activity, pre-fill the sign-up fields with the sign-in hints that you added to the intent.

public class SignUpNewUserActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Intent intent = getIntent();
        Credential credential = intent.getParcelableExtra("com.mycompany.myapp.SIGNIN_HINTS");

        // Pre-fill sign-up fields
        mUsernameView.setText(credential.getId());
        mDisplaynameView.setText(credential.getName()); // Might be null.

        ...
    }

    ...
}

Optionally, you can also check if the Credential object contains an ID token that has a verified email address. If so, you can skip your app's email verification step, since the email address has already been verified by Google.