forbid manual setup when email is empty

import android.support.annotation.NonNull;

import android.support.annotation.Nullable;

import android.util.Log;

import android.widget.Toast;

import foundation.e.mail.Account;

import foundation.e.mail.Account.FolderMode;

    @Override

    public void onManualSetupButtonClicked(String email, String password) {

        EmailAddressValidator emailValidator = new EmailAddressValidator();

        if(email != null && email.length() > 0 && emailValidator.isValidAddressOnly(email))

            manualSetup(email, password);

        else

            Toast.makeText(context, R.string.account_setup_basics_manual_setup_empty_mail, Toast.LENGTH_LONG).show();

    }

    @Override

  <string name="account_setup_basics_password_hint">Mot de passe</string>

  <string name="account_setup_basics_show_password">Afficher le mot de passe</string>

  <string name="account_setup_basics_manual_setup_action">Configuration manuelle</string>

  <string name="account_setup_basics_manual_setup_empty_mail">L\'adresse email doit être spécifiée</string>

  <string name="account_setup_check_settings_title"/>

  <string name="account_setup_check_settings_retr_info_msg">Récupération des informations de compte\u2026</string>

  <string name="account_setup_check_settings_check_incoming_msg">Vérification des paramètres du serveur entrant\u2026</string>

    <string name="account_setup_basics_password_no_password_needed_hint">Please click next</string>

    <string name="account_setup_basics_show_password">Show password</string>

    <string name="account_setup_basics_manual_setup_action">Manual setup</string>

    <string name="account_setup_basics_manual_setup_empty_mail">Mail address cannot be empty</string>

    <string name="account_setup_check_settings_title"/>

    <string name="account_setup_check_settings_retr_info_msg">Retrieving account information\u2026</string>