Creating a shopping cart application with Provider

Create a new Flutter application named cart_provider and copy item.dart into your lib folder, as we have been doing in the previous sections. Also, add dependencies for Provider from pub.dev. Let's get started, as follows:

1. Create a new file named cart_model.dart and add the following code to it:

   import 'item.dart';
   import 'package:flutter/material.dart';
   class Cart with ChangeNotifier {
     List<Item> _items = populateItems();
     List<Item> _cart = [];
     List<Item> get items => _items;
     List<Item> get cart => _cart;
     void addToCart(Item item) {
       _cart.add(item);
       notifyListeners();
     }
     void removeFromCart(Item item) {
       _cart.remove(item);
       notifyListeners();
     }
   }

   As we studied in Chapter 3, Diving into...