Kotlin reflection on object instance

Question

I've been trying some stuff from kotlin.reflection during my project, and got stuck on something what occurs to me as hard to understand, I have declared object as follows:

object WebsiteMapping
{
    const val ADMIN = "/admin"
}

once I call:

Arrays
  .stream(WebsiteMapping::class.java.declaredFields)
  .forEach { field -> println(field.type) }

what I get is:

class java.lang.String
class mapping.WebsiteMapping

When I looked a little bit into what is behind declaredFields invocation I grasped why it works as it is, but is there any convenient way of taking only declared consts within that object without getting also root of the whole structure?

hotkey · Accepted Answer · 2018-06-28 19:48:46Z

4

The field with the type class mapping.WebsiteMapping is, basically, not the root of the structure but a special field generated in the object type that holds the reference to the singleton object.

In Kotlin, this field is named INSTANCE by convention. You can therefore filter the fields that you get from the class as follows:

WebsiteMapping::class.java.declaredFields
    .filter { it.name != "INSTANCE" }
    .forEach { println(it.type) }

Another solution is to switch from java.reflect.* to the Kotlin reflection API kotlin.reflect (needs a dependency on the kotlin-reflect module), which automatically filters the property:

WebsiteMapping::class.memberProperties
    .forEach { println(it.returnType) }

answered Jun 28, 2018 at 19:48

hotkey

149k43 gold badges392 silver badges333 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Kotlin reflection on object instance

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related