public void subscribe(Context context){
            List<ActivityTransition> transitions = new ArrayList<>();

            transitions.add(
                    new ActivityTransition.Builder()
                            .setActivityType(DetectedActivity.WALKING)
                            .setActivityTransition(ActivityTransition.ACTIVITY_TRANSITION_ENTER)
                            .build());

            transitions.add(
                    new ActivityTransition.Builder()
                            .setActivityType(DetectedActivity.WALKING)
                            .setActivityTransition(ActivityTransition.ACTIVITY_TRANSITION_EXIT)
                            .build());

            ActivityTransitionRequest request = new ActivityTransitionRequest(transitions);

            Intent intent = new Intent(context, TransitionsReceiver.class);
            intent.setAction(TransitionsReceiver.TRANSITIONS_RECEIVER_ACTION);

            pendingIntent = pendingIntent.getBroadcast(context,0,intent,PendingIntent.FLAG_CANCEL_CURRENT);

            Task<Void> task =
                    ActivityRecognition.getClient(context)
                            .requestActivityTransitionUpdates(request, pendingIntent);

            task.addOnSuccessListener(
                    new OnSuccessListener<Void>() {
                        @Override
                        public void onSuccess(Void result) {
                            Log.i("Shield", "Transitions Api was successfully registered.");
                        }
                    });
            task.addOnFailureListener(
                    new OnFailureListener() {
                        @Override
                        public void onFailure(Exception e) {
                            Log.e("Shield", "Transitions Api could not be registered: " + e);
                        }
                    });
    }