To cope with the previous situation, Kotlin allows you to use parameters for methods and attributes, composing what is known as parametrized classes. Certain constraints on class instance creation sound convenient, so that cages only host animals, and no other wrong type.However, this looks rather naïve and not convenient, since it introduces code duplication. You could use something like CatCage, for example.

A new redefinition of Cage is necessary if classifying other species, i.e.However, the above sample has several potential issues to take into account: So you can easily use it as follows: val dog = Dog(id = 0, name = 'Doglin', furColor = FurColor.BLACK) Try this out in your playground: data class Dog(val id: Int, val name: String, val furColor: FurColor)Ĭlass Cage(var dog: Dog, val size: Double) For instance, for a dog, you could do the following. Following an object-oriented programming approach, you will most likely put each animal in a cage and declare several attributes and actions associated. Imagine you are managing a zoo or an exotic pet shop so that you have to organize and keep a reference of all animal species available. You can also paste in the starting code and follow along at. Open or paste these files in your favorite Kotlin editor or playground. The project contains PlaygroundData.kt which includs all the data classes available, and MainKotlinPlayground.kt with the main() function you’ll use in order to test your code. Begin by downloading the starter project using the Download Materials button at the top or bottom of this tutorial. Let’s set up an example of a rather common scenario. If you need to get started learning Kotlin, check out Kotlin For Android: An Introduction. Note: This tutorial assumes you’re comfortable working in Kotlin.

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