How to wait for result of speech recognition in android?

Question

I am using recognition listener for speech recognition in android. The basic construct of my class is as follows:

class SpeechInput implements RecognitionListener {

    Intent intent;
    SpeechRecognizer sr;
    boolean stop;

    public void init() {
        sr = SpeechRecognizer.createSpeechRecognizer(context);
        sr.setRecognitionListener(this);
        intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
        intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
        intent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE,context.getPackageName());
        intent.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS,3);
    }

    ...

}

I am stuck in a situation where I want to run android recognition listener in a loop, something over the lines of:

for(int i=0; i<N; i++) {
       // Some processing code
       sr.startListening(intent);
}

Now, I want to wait for the output before it starts listening again. In order to achieve this, I tried to use locking mechanism as follows:

for(int i=0; i<N; i++) {
       // Some processing code
       sr.startListening(intent);
       stop = false; 
       new Task().execute().get();
}

where Task is an asyncTask defined as follows:

private class Task extends AsyncTask<Void,Void,Void> {

        @Override
    protected Void doInBackground(Void... params) {
        try {
            int counter = 0;
            while(!stop) {
                counter++;
            }
        } catch(Exception e) {
        }
        return null;
    }
}

The boolean value 'stop' is updated in the 'onResults' method of RecognitionListener as follows:

public void onResults(Bundle results) {
    ...
    stop = true;
}

The problem is that speech recognition is not working at all. Nothing is happening, it is not even starting. I guess this is because the asyncTask is taking up all the processor time. Can you please guide me towards an architecture where I would be able to achieve this? Thank you.

RaphMclee · Accepted Answer · 2015-04-07T10:12:32.877

3

Restart the listening when you receive a result. No loop needed, no waiting needed.

I'm not an expert on Speech recognition on Android but you are probably blocking the Main thread with the call

new Task().execute().get();

So the speech recognition is probably never started.

edited Apr 07 '15 at 10:12

answered Apr 01 '15 at 13:22

RaphMclee

1,623
13
16

Thanks mate. Solves the problem. – Bhoot Apr 06 '15 at 08:23

score 3 · Answer 2 · answered Jun 30 '15 at 05:58

It is important to note that the methods of Speech Recognition API of Android can only be invoked from the main thread and all the callbacks are executed on the main thread of the application.

As a result, when the main thread gets blocked, the recognition listener also gets blocked which is why nothing happens when I try to execute speech recognition the way shown in the question.

Taking a cue from accepted answer, I used the onResults method of RecognitionListener interface to restart the listener as shown below:

public void onResults(Bundle results) {
    ...
    sr.startListening(intent);
}

How to wait for result of speech recognition in android?

2 Answers2