Kotlin commonMain with java.io.Serializable - kotlin

Question

Problem
I have a data class in commonMain (called Person) that I would like to access from jvmMain as type java.io.Serializable.
I have a solution, which is shown below, but I was wondering if this is the best approach. I also found that the library kotlinx.serialization exists, but I'm not sure if it can be a solution.
Current code and solution: expected and actual types
This code works fine, although the required DummyInterface may be a bit useless.
// CommonMain
expect interface Serializable
data class Person(val name: String) : Serializable
// jsMain
interface DummyInterface
actual typealias Serializable = DummyInterface
//jvmMain
actual typealias Serializable = java.io.Serializable
fun main(args: Array<String>) {
val p1: java.io.Serializable = Person("abc")
println(p1)
}
Tried and failed code with kotlinx.serialization
// gradle.kotlin.kts
plugins {
application
kotlin("multiplatform") version "1.4.32"
kotlin("plugin.serialization") version "1.4.32"
}
repositories {
mavenCentral()
}
kotlin {
jvm {
compilations.all {
kotlinOptions.jvmTarget = "11"
}
withJava()
}
js(IR) {
binaries.executable()
browser {}
}
sourceSets {
val commonMain by getting {
dependencies {
implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.1.0")
}
}
val jvmMain by getting {
dependencies {
implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.1.0")
}
}
}
}
// commonMain/kotlin/Person.kt
import kotlinx.serialization.*
#Serializable
data class Person(val name: String)
// jvmMain/kotlin/main.kt
fun main(args: Array<String>) {
// Fails with: "Type mismatch: inferred type is Person but Serializable was expected"
val p1: java.io.Serializable = Person("abc")
println(p1)
}
I know why it fails with a type mismatch, but I would hoping that the kotlinx.serialization plugin would magically add the interface java.io.Serializable to the Person data class.
Question
Is solution with expected and actual types, the best solution for this problem?
Would kotlinx.serialization also be able to provide a solution? If so, what code should I alter?

Answer 1

kotlinx.serialization wasn't exactly developed as an java.io.Serializable abstraction or something. It's a purely kotlin serialization library, for serializing/deserializing JSON objects.
Yes, your first approach is a proper solution I'd say.
There is a similar implementation for Parcelize, you could check out moko-parcelize, it's doing the same thing.