A very simple class utilizing TTS engine on an Android phone to say something out loud.

Voice.kt

/**
 * Utilizes TextToSpeech engine on the device to speak out loud what you want it to say.
 */
@PerApp
class Voice @Inject constructor(
    private val context: Application
) {
    private var isTtsReady = false
    private var tts: TextToSpeech? = null
    private var postponedTextToSay: String? = null

    /**
     * Call this in order to prepare TextToSpeech engine.
     */
    fun prepareTts() {
        if (isTtsReady) return

        tts = TextToSpeech(context, OnInitListener { status ->
            if (tts!!.setLanguage(Locale.getDefault()) == TextToSpeech.LANG_COUNTRY_AVAILABLE) {
                if (status == TextToSpeech.SUCCESS) {
                    isTtsReady = true
                    postponedTextToSay?.let {
                        say(it)
                        postponedTextToSay = ""
                    }
                }
            }
        })
    }

    fun say(text: String) {
        if (isTtsReady) {
            tts?.speak(text, TextToSpeech.QUEUE_FLUSH, null, "Unique Utterance ID")
        } else {
            postponedTextToSay = text
        }
    }

    /**
     * Release non-managed resources. Call this once you're done using the Voice.
     */
    fun release() {
        tts?.shutdown()
        isTtsReady = false
    }
}