Table<User, Item, Rating> table = new Table<>(); table.addEmptyCol(new Item("Television")); table.addEmptyCol(new Item("Sofa")); User user = new User("Anakin"); Item item = new Item("Light Sabre"); table.put(user, item, new Rating(5)); Item item1 = new Item("Helmet"); table.put(user, item1, new Rating(7)); Rating rating = table.get(user, item); rating.setRating(rating.getRating() + 10); User user1 = new User("Obi-Wan"); table.put(user1, item, new Rating(8)); table.put(user1, new Item("Television"), new Rating(0));