Locale swedishLocale = new Locale("sv");

// Check availability of language before trying to call speak()
int languageAvailability = textToSpeech.isLanguageAvailable(swedishLocale);

// These two return codes mean that either the TTS engine doesn't support a
// language, or it does but is missing the voice data.
if (languageAvailability == TextToSpeech.LANG_MISSING_DATA
                || languageAvailability == TextToSpeech.LANG_NOT_SUPPORTED) {
    Timber.d("Language code %s is not supported on this device", language.getCode());

    // SpeechStatus is an enum I use to map TTS errors
    return SpeechStatus.ERROR_LANGUAGE_NOT_SUPPORTED;
}