Hello does anyone know the difference between ` class` and ` kotlinlang #announcements

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Title

v

Viet Hoang

02/12/2019, 1:46 AM

Hello, does anyone know the difference between

::class

and

.javaClass.kotlin

? And why is that in below example, the later declaration works but the prior doesn’t ?

class Test {
    fun testMethod() {
        this::class.memberProperties.forEach { println(it.get(this)) } // compile error 
        this.javaClass.kotlin.memberProperties.forEach { println(it.get(this)) }
    }

a

alex2069

02/12/2019, 1:58 AM

I can't tell you why it's like this, but:

this::class

is

KClass<out Test>

Whereas

this.javaClass.kotlin

is

KClass<Test>

And if you go down the chain and look at each type explicitly:

val k1: KClass<out Test> = this::class
val m1: Collection<KProperty1<out Test, *>> = k1.memberProperties
val p1: KProperty1<out Test, *> = m1.first()

val k2: KClass<Test> = this.javaClass.kotlin
val m2: Collection<KProperty1<Test, *>> = k2.memberProperties
val p2: KProperty1<Test, *> = m2.first()

I imagine it's because

this::class

could be this class or its inheritors

Having said that - if the class is final then I would expect

this::class

to be

KClass<Test>

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