private TextToSpeech tts;

/* ... */

tts = new TextToSpeech(this, new TextToSpeech.OnInitListener() {
    @Override
    public void onInit(int status) {
        if (status == TextToSpeech.SUCCESS) {
            String text = "Hello world";
            tts.setLanguage(Locale.US);
            tts.speak(text, TextToSpeech.QUEUE_ADD, null, null);
        }
    }
});

Set<String> features = new HashSet<>();
features.add("male");
Voice voice = new Voice("en-us-x-sfg#male_2-local", new Locale("en","US"), 400, 200, true, features);
tts.setVoice(voice);

if (!isGoogleTTSInstalled()) {
    installGoogleTTS();
} else {
    openTTSSettingsToInstallUnsupportedLanguage();
}

createGoogleTTS();

private boolean isGoogleTTSInstalled() {
    Intent ttsIntent = new Intent();
    ttsIntent.setAction(TextToSpeech.Engine.ACTION_CHECK_TTS_DATA);
    PackageManager pm = this.getPackageManager();
    List<ResolveInfo> listOfInstalledTTSInfo = pm.queryIntentActivities(ttsIntent, PackageManager.GET_META_DATA);
    for (ResolveInfo r : listOfInstalledTTSInfo) {
        String engineName = r.activityInfo.applicationInfo.packageName;
        if (engineName.equals("com.google.android.tts")) {
            return true;
        }
    }
    return false;
}

private void installGoogleTTS() {
    Intent goToMarket = new Intent(Intent.ACTION_VIEW).setData(Uri.parse("market://details?id=com.google.android.tts"));
    startActivity(goToMarket);
}

// use this if attempting to speak in foreign locale results in onError() being called by your UtteranceProgressListener.
private void openTTSSettingsToInstallUnsupportedLanguage() {
    Intent intent = new Intent();
    intent.setAction("com.android.settings.TTS_SETTINGS");
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    startActivity(intent);
}

private void createGoogleTTS() {
    tts = new TextToSpeech(this, new TextToSpeech.OnInitListener() {
        @Override
        public void onInit(int status) {
            if (status == TextToSpeech.SUCCESS) {
                /* ... */
            }
        }
    }, "com.google.android.tts");
}

Set<Voice> availableVoices = textToSpeechSystem.getVoices();
List<Locale> availableLocales = Arrays.asList(Locale.getAvailableLocales());

for (Voice voice : availableVoices) {
    if ( (voice.getLocale().getLanguage().equals(Locale.getDefault().getLanguage())) &&
         (availableLocales.contains(voice.getLocale())) &&
         (!voice.isNetworkConnectionRequired()) &&
         (tts.isLanguageAvailable(voice.getLocale()) != TextToSpeech.LANG_MISSING_DATA) &&
         (tts.isLanguageAvailable(voice.getLocale()) != TextToSpeech.LANG_NOT_SUPPORTED) &&
         (!voice.getFeatures().contains(TextToSpeech.Engine.KEY_FEATURE_NOT_INSTALLED)) ) {
        /* ... */
    }
}