public void execute(Game game, String string) {
    Item item = game.getCurrentRoom().getItem(string);
        if(item != null){
            if(item instanceof Openable) {
                Openable itm = (Openable) item;
                itm.open();
        }  else  { game.getUI().println("Tento predmet sa neda otvorit");}
        } else {
            game.getUI().println("Taky predmet tu nikde nevidim");
        }
    }


chybu vyhadzuje itm.open();

method open in interface items.Openable cannot be applied to given types
  required: textgame.UserInterface
  found: no arguments