Why is the Translation client not returning translated text?

Question

I'm still a newby in Kotlin and Android development, and I wanted to translate some text (ingredients from a product) to Spanish given a language code.

Code (forget Spanish error messages) from a function:

private fun translateTextToSpanish(ingredients: String, it: String?): String {
    val opcionesTraductor: TranslatorOptions
    if(it == "en")
        opcionesTraductor = TranslatorOptions.Builder()
            .setSourceLanguage(TranslateLanguage.ENGLISH)
            .setTargetLanguage(TranslateLanguage.SPANISH)
            .build()
    else
        if(it == "fr")
            opcionesTraductor = TranslatorOptions.Builder()
                .setSourceLanguage(TranslateLanguage.FRENCH)
                .setTargetLanguage(TranslateLanguage.SPANISH)
                .build()
        else
            if(it == "de")
                opcionesTraductor = TranslatorOptions.Builder()
                    .setSourceLanguage(TranslateLanguage.GERMAN)
                    .setTargetLanguage(TranslateLanguage.SPANISH)
                    .build()
            else
                if(it == "it")
                    opcionesTraductor = TranslatorOptions.Builder()
                        .setSourceLanguage(TranslateLanguage.ITALIAN)
                        .setTargetLanguage(TranslateLanguage.SPANISH)
                        .build()
                else
                    if(it == "pt")
                        opcionesTraductor = TranslatorOptions.Builder()
                            .setSourceLanguage(TranslateLanguage.PORTUGUESE)
                            .setTargetLanguage(TranslateLanguage.SPANISH)
                            .build()
                    else
                        if(it == "ru")
                            opcionesTraductor = TranslatorOptions.Builder()
                                .setSourceLanguage(TranslateLanguage.RUSSIAN)
                                .setTargetLanguage(TranslateLanguage.SPANISH)
                                .build()
                        else
                            opcionesTraductor = TranslatorOptions.Builder()
                                .setSourceLanguage(TranslateLanguage.ENGLISH)
                                .setTargetLanguage(TranslateLanguage.SPANISH)
                                .build()

    val traductorFinal = Translation.getClient(opcionesTraductor)
    var traduccion = ""
    val conditions = DownloadConditions.Builder()
        .requireWifi()
        .build()
    traductorFinal.downloadModelIfNeeded(conditions)
        .addOnSuccessListener {
            traductorFinal.translate(ingredients)
                .addOnSuccessListener { translatedText ->
                    traduccion = translatedText
                }
                .addOnFailureListener {
                    val dialog = AlertDialog.Builder(this)
                    dialog.setTitle("🗣 Error en la traducción")
                    dialog.setMessage("Se ha producido un error en la traducción.\n\nVuelve a intentarlo más tarde, y si el problema persiste, contacta con nosotros.")
                    dialog.setNegativeButton("Cerrar", null)
                    dialog.show()
                }
        }
        .addOnFailureListener {
            val dialog = AlertDialog.Builder(this)
            dialog.setTitle("🗣 Error en la traducción")
            dialog.setMessage("Se ha producido un error en la traducción.\n\nVuelve a intentarlo más tarde, y si el problema persiste, contacta con nosotros.")
            dialog.setNegativeButton("Cerrar", null)
            dialog.show()
        }
    return traduccion
}

This, as it is, returns "", which after analyzing the code, I can't figure out what's missing here...

I'm using the latest ML Kit API.

Thanks!

Answer 1

Solution:

private fun translateTextToSpanish(ingredients: String, it: String, callback: (String) -> Unit) {
    val sourceLanguage = TranslateLanguage.fromLanguageTag(it) ?: TranslateLanguage.ENGLISH
    val targetLanguage = TranslateLanguage.SPANISH
    val options = TranslatorOptions.Builder()
        .setSourceLanguage(sourceLanguage)
        .setTargetLanguage(targetLanguage)
        .build()

    val translator = Translation.getClient(options)
    val conditions = DownloadConditions.Builder().requireWifi().build()
    translator.downloadModelIfNeeded(conditions).addOnSuccessListener {
        translator.translate(ingredients).addOnSuccessListener { translatedText ->
            callback(translatedText)
        }.addOnFailureListener { exception ->
            val dialog = AlertDialog.Builder(this)
            dialog.setTitle("🗣 Error en la traducción")
            dialog.setMessage("Error: ${exception.message}")
            dialog.setNegativeButton("Cerrar", null)
            dialog.show()
        }
    }.addOnFailureListener { exception ->
        val dialog = AlertDialog.Builder(this)
        dialog.setTitle("🗣 Error en la traducción")
        dialog.setMessage("Error: ${exception.message}")
        dialog.setNegativeButton("Cerrar", null)
        dialog.show()
    }
}

Using callback() and lambda worked without issues.