How do I check whether a specific notification channel is enabled in Android Oreo?

with backwards compatibility:

public boolean isNotificationChannelEnabled(Context context, @Nullable String channelId){
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            if(!TextUtils.isEmpty(channelId)) {
                NotificationManager manager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
                NotificationChannel channel = manager.getNotificationChannel(channelId);
                return channel.getImportance() != NotificationManager.IMPORTANCE_NONE;
            }
            return false;
        } else {
            return NotificationManagerCompat.from(context).areNotificationsEnabled();
        }
    }