As Kotlin developers, we often face the decision between using sealed classes or enums when representing a fixed set of values or states. While both serve similar purposes, understanding their distinct capabilities can help us write more maintainable and expressive code. Let's dive into when and why you might choose one over the other.

The Familiar Enum

We all know enums - they're simple, straightforward, and perfect for representing a fixed set of constant values. Take this example:

enum class Status {
    SUCCESS,
    ERROR,
    LOADING,
    EMPTY
}

Enums shine when you need:

  • A fixed set of constant values
  • Basic value comparison
  • Serialization out of the box
  • To iterate over all possible values

Enter Sealed Classes

Sealed classes take things a step further. They're like enums on steroids, allowing each subclass to hold different types of data:

sealed class ApiResult {
    data class Success(val data: List<User>) : ApiResult()
    data class Error(val message: String, val code: Int) : ApiResult()
    object Loading : ApiResult()
    object Empty : ApiResult()
}

The real power of sealed classes becomes apparent when you're handling different states that need to carry specific data. When using when expressions, the compiler ensures you handle all possible cases - just like with enums.

Making the Choice

Choose enums when:

  • You just need a fixed set of related constants
  • The values don't need to hold state
  • You need to iterate over all values
  • Serialization needs to be straightforward

Go for sealed classes when:

  • Different variants need to hold different types of data
  • You want to leverage Kotlin's smart casting
  • You need more flexibility in representing state
  • You want to enforce type safety with complex states

Remember, sealed classes aren't replacements for enums - they're different tools for different jobs. The key is understanding your use case and choosing the right tool for better code maintainability.

What's your experience with sealed classes vs. enums? Share your thoughts in the comments below!

kotlin #programming #android #webdev

Author Of article : Kevin Petterson Read full article