Kotlin Sealed Interfaces: A Deep Dive into a Powerful New Feature

When Kotlin was first introduced, developers quickly fell in love with its powerful language features, including sealed classes. However, there was one thing that seemed to be missing: sealed interfaces. At the time, the Kotlin compiler was unable to guarantee that someone couldn’t implement an interface in Java code, which made it difficult to implement sealed interfaces in Kotlin.

But times have changed, and now sealed interfaces are finally available in both Kotlin 1.5 and Java 15 onwards. With sealed interfaces, developers can create more robust and type-safe APIs, just like they could with sealed classes. In this blog post, we’ll take a deep dive into Kotlin sealed interfaces and explore how they can help you build better code. We’ll cover everything from the basics of sealed interfaces to advanced techniques and best practices, so get ready to master this powerful new feature!

Basics of Sealed Interfaces in Kotlin

Like sealed classes, sealed interfaces provide a way to define a closed hierarchy of types, where all the possible subtypes are known at compile time. This makes it possible to create more robust and type-safe APIs, while also ensuring that all the possible use cases are covered.