Hi. I'd like to use Java's standard serialisation ...

# serialization

[Gus]

Hi. I'd like to use Java's standard serialisation (e.g., ObjectOutputStream) with Kotlin data classes, and I tried using this library as follows:

@Serializable
internal data class FileSessionPublicKeyData(
    val keyId: ByteArray,
    val keyDer: ByteArray,
    val creationTimeTimestamp: Long
)

But I get java.io.NotSerializableException: tech.relaycorp.awala.keystores.file.FileSessionPublicKeyData when I try to save a value to a file using ObjectOutputStream, which I guess that @Selializable doesn't actually implement Java's Serializable interface. Is there any way to do this? I don't want to use JSON, protobuff, etc.

[ephemient]

kotlinx.serialization.Serializable has no relation to java.io.Serializable

[ephemient]

if you want to make your object Java serializable, you need to write it like Java,

import java.io.Serializable

class FileSessionPublicKeyData(
    ...
) : Serializable {
    companion object {
        // required if you want to allow for serialization across compatible changes
        private const val serialVersionUID = (some constant Long)
    }
}

[ephemient]

if you want both kotlinx.serialization and Java serialization, then you need to declare both, e.g.

import java.io.Serializable as JavaSerializable
import kotlinx.serialization.Serializable

@Serializable
class FileSessionPublicKeyData(
    ...
) : JavaSerializable

[Gus]

Gotcha. Thanks!

[Paul Griffith]

Unsolicited advice: Don't use java serialization if at all possible