public void saveUser() {
   String uuid;
   SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
   if (sharedPreferences.contains("uuid")) {
     uuid = sharedPreferences.getString("uuid", null);
   } else {
     uuid = UUID.randomUUID().toString();
     sharedPreferences.edit().putString("uuid", uuid).apply();
   }
   api.saveUser(uuid);
 }
  public void saveServer(Server server) {
    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);

    String uuid = server.getUuid();
    String name = server.getName();
    String hostname = server.getHostname();
    int rcon_port = server.getPort();
    int query_port = server.getQueryPort();

    String user_uuid = sharedPreferences.getString("uuid", null);

    if (user_uuid == null) {
      Ln.e("User uuid is null.");
    } else {
      api.saveServer(uuid, name, hostname, rcon_port, query_port, user_uuid);
    }
  }
 public void checkAppUpdateAvailable(ApiCallback apiCallback) {
   api.getLastVersion(apiCallback);
 }