Android : Android show Notification when app is not open?

Is it possisble to only display a notification to the user when the app is not active. (Open but not active). At the moment, i have the following code, which displays a notification. However it is also displayed when the user is in the app, and that is kind of pointless.'

public void notifyNewOrders() {
        sp.play(soundId2, 1, 1, 0, 0, 1);
        int notificationId = 001;
        Intent viewIntent = new Intent(this, ListActivity.class);
        viewIntent.putExtra("01", "12");
        PendingIntent viewPendingIntent = PendingIntent.getActivity(this, 0,
                viewIntent, 0);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(
                this)
                .setSmallIcon(R.drawable.coffee_tea_icon)
                .setContentTitle("New Orders available!")
                .setContentText(
                        "New orders are available. Want to make some easy money?")
                .setContentIntent(viewPendingIntent);
        NotificationManagerCompat notificationManager = NotificationManagerCompat
                .from(this);
        notificationManager.notify(notificationId, notificationBuilder.build());
    }

Could i check if the activity is being viewed. And if not, display the notification? How can this be done. Thank you.