Trigger speech to text translation

private void startListening() {

     //Intent to listen to user vocal input and return result in same activity
    Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
    
   //Use a language model based on free-form speech recognition.
    intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
            RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
    intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE, Locale.getDefault());

    //Message to display in dialog box
    intent.putExtra(RecognizerIntent.EXTRA_PROMPT,
            getString(R.string.speech_to_text_info));
    try {
        startActivityForResult(intent, REQ_CODE_SPEECH_INPUT);
    } catch (ActivityNotFoundException a) {
        Toast.makeText(getApplicationContext(),
                getString(R.string.speech_not_supported),
                Toast.LENGTH_SHORT).show();
    }
}

Get translated results in onActivityResult

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    switch (requestCode) {
    case REQ_CODE_SPEECH_INPUT: {
        if (resultCode == RESULT_OK && null != data) {

            ArrayList<String> result = data
                    .getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
            txtSpeechInput.setText(result.get(0));
        }
        break;
    }

    }
}

Output

The following code can be used to trigger speech-to-text translation without showing a dialog:

public void startListeningWithoutDialog() {
    // Intent to listen to user vocal input and return the result to the same activity.
    Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);

    // Use a language model based on free-form speech recognition.
    intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
            RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
    intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE, Locale.getDefault());
    intent.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS, 5);
    intent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE,
            appContext.getPackageName());

    // Add custom listeners.
    CustomRecognitionListener listener = new CustomRecognitionListener();
    SpeechRecognizer sr = SpeechRecognizer.createSpeechRecognizer(appContext);
    sr.setRecognitionListener(listener);
    sr.startListening(intent);
}

The custom listener class CustomRecognitionListener used in the code above is implemented as follows:

class CustomRecognitionListener implements RecognitionListener {
    private static final String TAG = "RecognitionListener";

    public void onReadyForSpeech(Bundle params) {
        Log.d(TAG, "onReadyForSpeech");
    }

    public void onBeginningOfSpeech() {
        Log.d(TAG, "onBeginningOfSpeech");
    }

    public void onRmsChanged(float rmsdB) {
        Log.d(TAG, "onRmsChanged");
    }

    public void onBufferReceived(byte[] buffer) {
        Log.d(TAG, "onBufferReceived");
    }

    public void onEndOfSpeech() {
        Log.d(TAG, "onEndofSpeech");
    }

    public void onError(int error) {
        Log.e(TAG, "error " + error);

        conversionCallaback.onErrorOccured(TranslatorUtil.getErrorText(error));
    }

    public void onResults(Bundle results) {
        ArrayList<String> result = data
                .getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS);
        txtSpeechInput.setText(result.get(0));
    }

    public void onPartialResults(Bundle partialResults) {
        Log.d(TAG, "onPartialResults");
    }

    public void onEvent(int eventType, Bundle params) {
        Log.d(TAG, "onEvent " + eventType);
    }
}