Cart design

Design the data class structure for the shopping cart.

Project: Shopping cart

In this 5-lesson project you'll build a shopping cart. Each lesson adds one piece, and by the final lesson you'll have a complete app.

You'll use what you learned before:

data classes with data class
mutable lists with mutableListOf
iteration with for
output with println

You'll add items, calculate totals and list the cart step by step. Ready? Let's start.

data class Product

To represent a product, Kotlin uses data class. This is a shorthand for data-holding classes; you'll see the details later.

data class Product(val name: String, val price: Double)

This single line creates a class with name and price fields. data class auto-generates toString, equals and more.

To hold products, create an empty list with mutableListOf<Product>(); this will also be covered in detail later.

Exercise Define the empty cart

Define a data class Product(val name: String, val price: Double). In fun main(), create an empty cart with val cart = mutableListOf<Product>() and print its size with println(cart.size).

Show example solution

data class Product(val name: String, val price: Double)

fun main() {
    val cart = mutableListOf<Product>()
    println(cart.size)
}

Test yourself

What does a shopping cart need first?
- A database
- A class
- A list to hold items
- A file
Show answer

A list to hold items — A cart uses a list to hold items.

Complete the data class definition

data ____ Product(val name: String, val price: Double)

Show answer

data class Product(val name: String, val price: Double)

Match the cart concepts

data class

Data class
mutableListOf

Create list
Product

Product class
cart.size

Item count

Next lesson: Adding items

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