Hi I was trying to see if I could get some information from kotlinlang #getting-started

# getting-started

08/16/2021, 8:06 PM

Hi. I was trying to see if I could get some information from a

KFunction

kotlin-reflect

kotlinx-metadata-jvm

), but I couldn't get

Metadata

with valid information, so I have a question. What I want to achieve is as follows. 1. get the information of arguments and return values from

KFunction

javaConstructor

javaMethod

KFunction

A simple verification with the following code shows that although the

Metadata

annotation can be retrieved from a

KFunction

, the contents are almost empty.

package org.example

import kotlin.reflect.KFunction

data class DataClass(val value: String)

fun main() {
    val function: KFunction<*> = ::DataClass
    val metadata: Metadata = function::class.java.getAnnotation(Metadata::class.java)!!

    println(metadata.data1.asList()) // -> []
    println(metadata.data2.asList()) // -> []
}

On the other hand, looking at the bytecode of the

synthetic class

generated as a

FunctionReference

, it looks like there is a valid

Metadata

. How can I get this

Metadata

If there is another way to get information from

KFunction

without using

kotlin-reflect

, I would be grateful if you could let me know. Thank you.

It solved itself in another way.

KFunction

retrieved as

Reference

can be cast to

kotlin.jvm.internal.FunctionReference

, so various information could be read from it. From

(functionReference.owner as ClassBasedDeclarationContainer).jClass

, we could also read information about the

Class

from which it was defined.