How to create a RecognitionListener in Android Kotlin-CodePudding

I'm new to Kotlin, and essentially I'm trying to create an app that counts how many times someone says a keyword. I'm using the SpeechRecognizer API, and I'm having trouble creating a RecognitionListener.

Below is the problematic code:

private val speech: SpeechRecognizer by lazy { SpeechRecognizer.createSpeechRecognizer(this) }

    if (SpeechRecognizer.isRecognitionAvailable(this)) {
        Toast.makeText(this, "Voice recognition available.", Toast.LENGTH_SHORT).show()
        val speechRecognizer = speech.setRecognitionListener(this)

        val recognizerIntent = Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH).apply {
            putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, RecognizerIntent.LANGUAGE_MODEL_WEB_SEARCH)
            putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE, applicationContext.packageName)
            putExtra(RecognizerIntent.EXTRA_MAX_RESULTS, 3)
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                putExtra(RecognizerIntent.EXTRA_PREFER_OFFLINE, true)
            }
        }

        speechRecognizer.startListening(recognizerIntent)

The problem comes in the line wherein I create the speechRecognizer:

       val speechRecognizer = speech.setRecognitionListener(this)

There's a red squiggly underneath this, saying there is a type mismatch: "Inferred type is MyActivity but RecognitionListener! was expected."

I don't quite understand this... isn't what I'm doing creating a RecognitionListener? Then why does it need a RecognitionListener to be passed into it? I know I've gone horribly wrong somewhere, but I don't know where and I'm lost after searching all over online to find an answer. Any help would be greatly appreciated.

If it's helpful, I've been trying to follow Stephen Vinouze's guide on hot keyword listening found here: https://betterprogramming.pub/implement-continuous-speech-recognition-on-android-1dd2f4b562fd

Anyway, thanks in advance. Let me know if there is anything else I need to provide.

Stephen

CodePudding user response：

isn't what I'm doing creating a RecognitionListener?

No. The method that you are calling is setRecognitionListener(). A "set" prefix on a method name generally means that you are providing the thing that is being set, in this case a RecognitionListener.

I've been trying to follow Stephen Vinouze's guide on hot keyword listening found here

Perhaps try this one or this one.

CodePudding user response：

Your error is on the setRecognitionListener line, not the create one. This is fine:

SpeechRecognizer.createSpeechRecognizer(this)

You're calling this method which takes a Context, which your Activity is. But then you need to call this method:

public void setRecognitionListener (RecognitionListener listener)

which takes a RecognitionListener, which your Activity apparently is not.

The way the tutorial you posted is doing it is to make the Activity implement that RecognitionListener interface, like this:

class MyActivity : AppCompatActivity(), RecognitionListener {

and then implement all the abstract methods on the interface (Ctrl I and then select them all is the quick way to do it in Android Studio). Since your Activity is now a RecognitionListener, you can pass it into that call as this like you were trying to do!

The tutorial doesn't mention this from what I can see? Except saying "since you’ve also implemented the RecognitionListener" and expecting you to know how to do that. But in the Speak up time! section you can see their implementation for a couple of those callbacks