I solved ^ by using .javaclass, but is there a kotlin idiomatic way to do the same? I was using a

@JvmField

annotation, so maybe that's what makes the above not work?

Is there any way to reflectively invoke a

KCallable

with default parameters, without explicitly supplying those parameters?

Hi folks! New to using reflection APIs. I was wondering what the performance impact would be for

::functionReference.name

? More details in the 🧵

How can I shadow and relocate reflect correctly? I tried relocating the kotlin to kotlin1910. But makes kotlin reflect can't find

kotlin1910.kotlin1910_builtins

. Then, I added custom transformers for avoiding

shadow

relocate the

.kotlin_builtins

constant in kotlin reflect. And relocate the

kotlin/kotlin.kotlin_builtins

to

kotlin1910/kotlin1910.kotlin_builtins

But the reflect can't find the builtin class

AssertionError: Built-in class kotlin1910.Any is not found

I would like to remove the type property on this interface and instead figure it out at runtime. Is this possible using reflection, and if so: how?

interface Dispatcher<T : Request<R>, R> {

    val type: KClass<T>

    suspend fun dispatch(
        request: T,
    ): R
}

Is there an easy way to check if a method in a subclass overrides a method from an interface using the Kotlin reflection API? In particular if the interface is Java and uses Generics.

To get a list of all the constructor properties of a Class, I either need reflection (with kotlin-reflect), or do it at compile time with Kapt or KSP. Is that right? I have a KType and I'd like to know its constructor properties - at runtime I've got

(kType.classifier as KClass<*>).constructors

and that requires kotlin-reflect. Any alternatives?

Does kotlin reflection provide a way to obtain the docstring used for a class/property?

There's something pretty weird in the behavior of reflect. I have a value class wrapping a UUID (which while investigating this, I've realized might be a bit pointless). I have a data class containing that value class, and upon reflection, it is not null, when in fact it is null. If the same class is a normal class instead, in reflection it's null as expected. Is this a bug in reflect or am I just crazy for using a value class in this way?

Hello. Reflection noob but I'm basically trying to change the value of a static field in a java class. Here's the java class: https://github.com/tink-crypto/tink-java/blob/main/src/main/java/com/google/crypto/tink/CryptoFormat.java Here's my reflection code that fails:

val field = CryptoFormat::class.java.getDeclaredField("NON_RAW_PREFIX_SIZE")

     field.isAccessible = true
     
     val modifers = field.javaClass.getDeclaredField("modifiers")
     modifers.isAccessible = true
     modifers.setInt(field, field.modifiers and java.lang.reflect.Modifier.FINAL.inv())
     
     field.setInt(null, 2000)

     val newValue = CryptoFormat.NON_RAW_PREFIX_SIZE
     println("NON_RAW_PREFIX_SIZE is now: $newValue")

Error:

java.lang.NoSuchFieldException: modifiers

Is there any way to get the name of a parameter as

String

? e.g.

fun add(a: Int, b: Int) {
  println("${a::name} is $a") // a is 5
}

Hello, everyone! 👋 How do I declare a interface using Kotlin reflections? KClass is missing "isInterface" and

KClassifier.createType

throws on me because the internal descriptor is null/faulty (found at

core/reflection.jvm/src/kotlin/reflect/full/KClassifiers.kt:48

, I'm using 2.0.0-RC1), I'm guesstimating it's because I have no constructors set, but this shouldn't be needed for an interface, right?

Given a class definition

class Request<I>(val body: I)

can I get the

KType

of

I

when the

Request

is constructed? Nothing is reified and I definitely cannot call

typeOf<I>

.

If I have a function with overloading, how can I get a

KFunction

reference to one of the overloads? I found I can use

val ref: (String) -> Unit

, for instance, as a way to disambiguate but the resulting type is not

KFunction

. It seems like I can cast this without everything crashing, but it's messy to use and not sure how stable that is.

Howdy all. I have a question. I have MVC controller classes and action methods (ehh functions) on those classes. The framework is in Java, but all our code is Kotlin. We looooooove KFunction and KClass as that allowed us to move away from string references to methods and classes as prescribed by the Java framework, giving us really cool type safety and refactorability. Anyway, the authorization is implemented with annotations on the controller classes and their methods. For example

@RequiresAnyUserPermissionOf(...)

that takes one or more permission enum instances. We check on each incoming request that that user user is allowed to the action by using reflection to get the annotation of the method and the class and all superclasses (up to some point). I consider caching all this by making some maps like

Map<KFunction<Result>, List<Permission>>

and

Map<KClass<Controller>, List<Permission>>

so it is all cached and we do not have to (recursively) reflect all over the place to now what permissions are on a certain controller class or controller action method. I have no clue what a KClass or KFunction actually is! Would this be a good idea? Or should I make these maps based on string representations (and the convert the KFunction or KClass to a string when doing a lookup)? Or doing a bunch of these reflections class to find the annotations soooooo fast that I should not bother at all... Just curious what you have to say on this, and as to how a KFunction or KClass actually is represented in memory.

Hello everyone I'm having trouble figuring out an unresolved reference I'm fairly certain i've used those imports before

import kotlin.reflect.full.findAnnotation
 import kotlin.reflect.full.primaryConstructor

but now all I'm getting is Unresolved reference: full although

import kotlin.reflect.KClass
seems to work perfectly fine.

not sure what im missing to be honest, but any assistance would be highly appreciated This is happening in my JVM module, and it works fine in my androidMain. I have the dependency set to both. P.S Koltin 2.0.20 Reflect 2.0.20

Just wanna spread some love: KFunction alone is enough of a reason to ditch Java and go all in on Kotlin. We've removed all the pesky string representations of methods from our codebase! from

"some.package.ControllerName.actionMethod"

we now use

ControllerName::actionMethod

: type safe, refactor friendly, less prone to bugs, and just plain stupid that this is still (2024!) not possible in Java. Thanks to whomever got this right in Kotlin, I enjoy my working life on the JVM a lot better since. 💚💛❤️

Hi, I was wondering if any one has had an issue where when getting the value of a value class using get on the Kproperty, get returns not null even if the property is actually null. It correctly returns null when directly grabbing the property

OuterClass::valueClass

but not when using the KProperty returned form

OuterClass::class.declaredMemberProperties

Minimum repro in thread🧵

oook

val x = fun(arg: String) { println(arg) }

val functionRef: KFunction<*> = x::invoke //valid, i can create a reflective handle to invoke.

x::class.members // 6 entries, 2 each of equals, hashcode, tostring. invoke is missing

is this expected behaviour?

I just put in a bunch of work to convert some code to kotlin from java, and it looks like ill have to convert it back unless i can figure out how to get

::invoke

off a

KClass

instance

Does the Kotlin reflection API's work in KMP? I see some support but not a whole lot. I really need to get functions from a given instance who have a particular annotation.

I'm observing unexpected behavior with

KClass<*>.declaredMemberProperties

. In the following code example:

data class A<T001>(
    val a001:Int?=null,
    val a002:Double?=null,
    val a003:Int?=null,
    val a004:Double?=null,
    val a005:Int?=null,
    var a007:Double?=null,
    val a008:Int?=null,
) {
    var a006: T001? = null
    val a009 = ""
    fun <T002> x() {}
}

A::class.declaredMemberProperties

provides a list of properties in the order

listOf(::a001, ::a002, ::a003, ::a004, ::a005, ::a006, ::a007, ::a008, ::a009)

, whereas at the java level, via

A::class.java.declaredMethods.filter { it.name.startsWith("get") }

, we get the expected order of properties declared in the primary constructor then properties declared in the body. Why does that happen?

I get that declaredMembers (and its subsets) is a List as an implementation detail, but is there a way to use kotlin's reflection to get the declared members in source order, more specifically in that primary constructor declared parameters come first in the list before the rest? (well, without querying the compiler-generated copy method to get the names of the parameters to use as a filter)

I have a metadata / reflect question. How can I get the

KClass

or

Class

from a

KmType

? For example, I have a

KmType

with the classifier being

KmClassifier.Class

which gives the name

kotlin/collections/List

. I have tried

Class.forName(...)

with it by replacing the

/

with

.

, but it doesn't work because the JVM type is actually

java.util.List

, so it throws a

ClassNotFoundException

for

kotlin.collections.List

. This is also true for things like

kotlin/Float

. Anyone knows a solution for this problem?

Is there a way to check in Kotlin Multiplatform is KType is a subtype of a different KType? I need something that will tell that

typeOf<List<Dog>>

is a subtype of

typeOf<Iterable<Animal>>

I'd like to enforce that JPA entities w/ child collections of type

MutableSet

have

orphanRemoval = true

on the

@OneToMany

annotation, but I can't figure out a good way to detect that using reflection. This works, but I don't like using

toString

since that might change. Is there another way that I'm missing that I could use to find all properties that are not an immutable Set?

@Test
    fun test() {
        val valid = LotEntity::class.declaredMemberProperties
            .asSequence()
            .filter { it.returnType.isSubtypeOf(Collection::class.starProjectedType) }
            .filterNot { it.returnType.toString().startsWith("kotlin.collections.Set") }
            .mapNotNull { it.javaField?.getAnnotation(OneToMany::class.java) }
            .all { oneToMany -> oneToMany.orphanRemoval }
        println(valid)
    }

i have an interface whose function has a default value but when i try to call its implementation via reflection i cannot call it as it says the parameter is missing

I'm getting a strange issue with

callBy

In which cases, for

@Serializable data class C

and applicable primary constructor params

...

, can the following expression

((::C).call(...)::copy).callBy(emptyMap())

fail with

KotlinReflectionInternalError(
    "Inconsistent number of parameters in the descriptor and Java reflection object: $arity != $expectedArgsSize\n" +
            "Calling: $descriptor\n" +
            "Parameter types: ${this.parameterTypes})\n" +
            "Default: $isDefault

with

expectedArgsSize

being the number of primary constructor declared properties + 1 and arity being the number of primary constructor declared properties + 2? It seems the -1 is due to the reflection logic determining that it's a bound reference to a static method, which seems nonsensical Reducing the case to ~100 lines made the issue vanish so I'm looking for things to pay attention to for debugging

Is it possible to create a KClass from within Java?

https://pastes.dev/xrBzbrlsTG I'm having this weird exception when getting the return type of a

KProperty<*>

in a delegate like such:

operator fun <T : GameDataEntry> getValue(
        thisRef: Any?,
        property: KProperty<*>
    ): T {
        @Suppress("UNCHECKED_CAST")
        return requireNotNull(getData(property.returnType.classifier as KClass<T>))
    }

Using Kotlin 2.1.10, is this a bug or am I just doing something wrong? The exception happens even when just attempting to get the

returnType