How can I pass value class parameter from Java? IDEA suggests me using the underlying type but it's ...

# getting-started

[Loney Chou]

How can I pass value class parameter from Java? IDEA suggests me using the underlying type but it's just a compilation error.

[ephemient]

https://kotlinlang.org/docs/inline-classes.html#calling-from-java-code

[ephemient]

oh, constructors are a bit trickier since they can't be renamed

[ephemient]

https://youtrack.jetbrains.com/issue/KT-47686/Support-generating-a-public-constructor-with-value-class-parameter-to-call-it-from-Java

[Loney Chou]

oh thanks 😄, it's just a normal function.

[Matt Nelson]

Another alternative is to wrap it in a sealed interface and use an invoke operator to instantiate it. So from Java it'll be MySealedValueClass.invoke("some value"), and from Kotlin it'll just be MySealedValueClass("some value")

https://kotlinlang.slack.com/archives/C3PQML5NU/p1651526497807819?thread_ts=1651318218.682619&cid=C3PQML5NU

[ephemient]

that loses any benefit of value class though; by using the interface it will always be boxed

[Matt Nelson]

Created a library for this specific issue of Kotlin value class not compiling to platform code.

https://github.com/05nelsonm/component-value-clazz

[ephemient]

that isn't a value at all though?

[Matt Nelson]

nope. It's just an abstract class that overrides hashCode , equals and toString which your implementation would extend. Functionally, it does the same thing as a Kotlin value class if that value class were to implement an interface