Does Kotlin have a Result type like Swift

Question

Swift has a Result type that is declared like this

enum Result<Success, Failure: Error> {     case success(Success)     case failure(Failure) } 

Which can be used like this:

enum FooError: Error {     case fizzReason     case barReason     case bazReason }  func returnResult() -> Result<String, FooError> {      // ... Just imagine this method returns an error }  switch returnResult() { case .success(let string):     print(s) case .failure(.fizzReason):     // do something case .failure(.barReason):     // do something case .failure(.bazReason):     // do something } 

Does Kotlin have a similar Data Type which can be used in the same manner?

Answer 1

I don't know whether Kotlin has something like that but here is an implementation that should do the same:

sealed class Result<out Success, out Failure>  data class Success<out Success>(val value: Success) : Result<Success, Nothing>() data class Failure<out Failure>(val reason: Failure) : Result<Nothing, Failure>() 

Actual example:

fun echoString(string : String) : Result<String, Exception> {     return if (string.isEmpty()) {         Failure(Exception("Error"))     } else {         Success(string)     } }  fun main(args : Array<String>) {     when(val result = echoString("string")) {         is Success -> println(result.value)         is Failure -> println(result.reason)     } }