could someone help me understand generics in this ...

# getting-started

[William Reed]

could someone help me understand generics in this situation:

This works fine:

val classes: List<KClass<*>> = listOf(
    Person::class,
    Teacher::class,
)

And this produces an error

val classes: List<KClass<Any>> = listOf(
    Person::class,
    Teacher::class,
)

(the difference being * vs Any)

I want to store any kclass, and don’t know the types. I thought * meant they all have the same type but i don’t know what it is

[William Reed]

using out Any also seems to work

[mkrussel]

I would read this to understand how * projection works. https://typealias.com/guides/star-projections-and-how-they-work/

The entire series starting at https://typealias.com/guides/illustrated-guide-covariance-contravariance/ is very well done.

[William Reed]

i actually found those articles after posting this and I am reading it now 🙂

[Joffrey]

KClass<Any> is the type of the Any class, while KClass<*> represents some class, but we don't know which one. If you want to store any KClass instance, you should use the star projection

[Joffrey]

Using KClass<out Any> also works because it is the type of classes that are subtypes of Any - so basically all of them.

[William Reed]

thank you. those articles actually did explain this better than i have understood it before

[William Reed]

i’ve found the official docs to be a little confusing