Data Classes: Your Own Types

Making your own types

Int, String, Double — those are Kotlin's built-ins. But PawWalk thinks in walkers, pets, and bookings. A data class lets you define a type of your own: a named bundle of values, with useful behavior generated for free.

Each val name: String inside the parentheses is a property — a piece of data that every value of the type carries. You read one with a dot: walker.name.

You've already met the most important data class in the app. Here it is for real: