Mastering Kotlin

Enums

Enums in Kotlin are very similar to those in Java. In the following we've defined a basic enum class named ArticleType:

enum class ArticleType {    Aside,    Blog,    Series}

This then can be used as a restricted type anywhere we would use any other existing type. In the following snippet, we've defined a property on Article using the new ArticleType enum:

data class Article(    var title: String,     val author: String,    val type: ArticleType)

When instantiating an instance of Article, we can reference the specific values exposed in our ArticleType enum:

fun main(args: Array<String>) {    val article1 = Article(        "Kotlin is great",        "Nate",        ArticleType.Blog    )}

By limiting the article types to those defined within ArticleType, we've provided a clear contract ...