[Project] Build a small inventory system

In this lesson you combine the classes, inheritance, lists, and maps covered so far into a simple inventory system. It is the capstone of this Dart introduction.

In real Flutter development the basic pattern is exactly this: represent something like a product with a class, manage many of them together in a list, and display them on screen.

The sample code represents a product (name and quantity) with class Item, manages the product listing with a list inside class Inventory, and prints a message according to each item's status.

Null safety, classes, and asynchronous work — everything covered in these lessons — are the foundations of real Flutter development too. Getting into the habit of writing small programs while paying attention to Dart's type system is the shortest path to using Dart and Flutter professionally.

📖 Reference code

class Item {
  String name;
  int quantity;
  Item(this.name, this.quantity);
}

class Inventory {
  List<Item> items = [];
  void add(Item item) {
    items.add(item);
  }
  void report() {
    for (var item in items) {
      String status;
      if (item.quantity == 0) {
        status = 'Out of stock';
      } else if (item.quantity < 5) {
        status = 'Low stock';
      } else {
        status = 'In stock';
      }
      print('${item.name}: ${item.quantity} ($status)');
    }
  }
}

void main() {
  var inv = Inventory();
  inv.add(Item('Notebook', 12));
  inv.add(Item('Eraser', 3));
  inv.add(Item('Ruler', 0));
  inv.report();
}

✍️ Your code

Type your code, then press "Run"

🧪 This site can't compile or run Dart directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).