Java Interoperability question: Can’t we access In...

# announcements

[Gopal S Akshintala]

Java Interoperability question: Can’t we access Inline Value class fields and constructor from Java? In the below example I don’t get any compiler error but fails at runtime with error: cannot find symbol

# Kotlin Value class

import io.vavr.control.Either
import io.vavr.kotlin.right

@JvmInline
value class Name(val s: String) {
    val length: Int
        get() = s.length
}

fun getAsName(): Either<String, Name> = right(Name("Kotlin"))

# Java Client

@Test
void testValueClass() {
  final var name = getAsName().get();
  Assertions.assertEquals(0, name.getLength());
}

# Error

error: cannot find symbol
    Assertions.assertEquals(0, name.getLength());
                                   ^
  symbol:   method getLength()
  location: variable name of type Name

[rnett]

You need to use @JvmName, see https://kotlinlang.org/docs/inline-classes.html#calling-from-java-code

[rnett]

I would assume that works the same for members

[Gopal S Akshintala]

hey @rnett thanks, but @JvmName is not applicable for fields

[rnett]

Can you use @get:JvmName? Or @property:?

[Gopal S Akshintala]

Do u mean something like this?

[rnett]

Yeah, I guess that doesn't work. I'm not sure what the "correct" way is, but for now you could just make an extension or helper method to use from Java.

[Gopal S Akshintala]

ya, that’s what I am planning, but from java, extensions fns calling isn’t fluent, I need to call like fn(thisObj) which hurts the API I am building using value classes

[gildor]

For now, there is no official way to access it from Java

[gildor]

https://youtrack.jetbrains.com/issue/KT-28135

[Gopal S Akshintala]

Thanks a lot Andrey