Android Speech Recognition Continuous Service

Class members in MainActivity

private int mBindFlag;
private Messenger mServiceMessenger;

Start service in onCreate()

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);

    Intent service = new Intent(activityContext, VoiceCommandService.class);
    activityContext.startService(service);
    mBindFlag = Build.VERSION.SDK_INT < Build.VERSION_CODES.ICE_CREAM_SANDWICH ? 0 : Context.BIND_ABOVE_CLIENT;

}

Bind service in onStart()

@Override
protected void onStart()
{
    super.onStart();

    bindService(new Intent(this, VoiceCommandService.class), mServiceConnection, mBindFlag);
}

@Override
protected void onStop()
{
    super.onStop();

    if (mServiceMessenger != null)
    {
        unbindService(mServiceConnection);
        mServiceMessenger = null;
    }
}

mServiceConnection member

private final ServiceConnection mServiceConnection = new ServiceConnection()
{
    @Override
    public void onServiceConnected(ComponentName name, IBinder service)
    {
        if (DEBUG) {Log.d(TAG, "onServiceConnected");} //$NON-NLS-1$

        mServiceMessenger = new Messenger(service);
        Message msg = new Message();
        msg.what = VoiceCommandService.MSG_RECOGNIZER_START_LISTENING; 

        try
        {
            mServiceMessenger.send(msg);
        } 
        catch (RemoteException e)
        {
            e.printStackTrace();
        }
    }

    @Override
    public void onServiceDisconnected(ComponentName name)
    {
        if (DEBUG) {Log.d(TAG, "onServiceDisconnected");} //$NON-NLS-1$
        mServiceMessenger = null;
    }

}; // mServiceConnection

In the service

@Override
public IBinder onBind(Intent intent)
{
    Log.d(TAG, "onBind");  //$NON-NLS-1$

    return mServerMessenger.getBinder();
}

Working example is given below,

MyService.class

public class MyService extends Service implements SpeechDelegate, Speech.stopDueToDelay {

  public static SpeechDelegate delegate;

  @Override
  public int onStartCommand(Intent intent, int flags, int startId) {
    //TODO do something useful
    try {
      if (VERSION.SDK_INT >= VERSION_CODES.KITKAT) {
        ((AudioManager) Objects.requireNonNull(
          getSystemService(Context.AUDIO_SERVICE))).setStreamMute(AudioManager.STREAM_SYSTEM, true);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }

    Speech.init(this);
    delegate = this;
    Speech.getInstance().setListener(this);

    if (Speech.getInstance().isListening()) {
      Speech.getInstance().stopListening();
    } else {
      System.setProperty("rx.unsafe-disable", "True");
      RxPermissions.getInstance(this).request(permission.RECORD_AUDIO).subscribe(granted -> {
        if (granted) { // Always true pre-M
          try {
            Speech.getInstance().stopTextToSpeech();
            Speech.getInstance().startListening(null, this);
          } catch (SpeechRecognitionNotAvailable exc) {
            //showSpeechNotSupportedDialog();

          } catch (GoogleVoiceTypingDisabledException exc) {
            //showEnableGoogleVoiceTyping();
          }
        } else {
          Toast.makeText(this, R.string.permission_required, Toast.LENGTH_LONG).show();
        }
      });
    }
    return Service.START_STICKY;
  }

  @Override
  public IBinder onBind(Intent intent) {
    //TODO for communication return IBinder implementation
    return null;
  }

  @Override
  public void onStartOfSpeech() {
  }

  @Override
  public void onSpeechRmsChanged(float value) {

  }

  @Override
  public void onSpeechPartialResults(List<String> results) {
    for (String partial : results) {
      Log.d("Result", partial+"");
    }
  }

  @Override
  public void onSpeechResult(String result) {
    Log.d("Result", result+"");
    if (!TextUtils.isEmpty(result)) {
      Toast.makeText(this, result, Toast.LENGTH_SHORT).show();
    }
  }

  @Override
  public void onSpecifiedCommandPronounced(String event) {
    try {
      if (VERSION.SDK_INT >= VERSION_CODES.KITKAT) {
        ((AudioManager) Objects.requireNonNull(
          getSystemService(Context.AUDIO_SERVICE))).setStreamMute(AudioManager.STREAM_SYSTEM, true);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
    if (Speech.getInstance().isListening()) {
      Speech.getInstance().stopListening();
    } else {
      RxPermissions.getInstance(this).request(permission.RECORD_AUDIO).subscribe(granted -> {
        if (granted) { // Always true pre-M
          try {
            Speech.getInstance().stopTextToSpeech();
            Speech.getInstance().startListening(null, this);
          } catch (SpeechRecognitionNotAvailable exc) {
            //showSpeechNotSupportedDialog();

          } catch (GoogleVoiceTypingDisabledException exc) {
            //showEnableGoogleVoiceTyping();
          }
        } else {
          Toast.makeText(this, R.string.permission_required, Toast.LENGTH_LONG).show();
        }
      });
    }
  }


  @Override
  public void onTaskRemoved(Intent rootIntent) {
    //Restarting the service if it is removed.
    PendingIntent service =
      PendingIntent.getService(getApplicationContext(), new Random().nextInt(),
        new Intent(getApplicationContext(), MyService.class), PendingIntent.FLAG_ONE_SHOT);

    AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
    assert alarmManager != null;
    alarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, 1000, service);
    super.onTaskRemoved(rootIntent);
  }
}

For more details,

https://github.com/sachinvarma/Speech-Recognizer

Hope this will help someone in future.