`val actuallObj: List<*> = listOf("a", "b")` how to get the contained object type (String here...

# getting-started

[Steven Wang]

val actuallObj: List<*> = listOf("a", "b")
how to get the contained object type (String here) ?

[nanodeath]

Java has type erasure, so you can't actually do that

[nfrankel]

i’m not sure i understand your question
as @nanodeath wrote, it’s not possible to get the type at runtime because of type erasure
otherwise, it’s inferred at compile-time by the kotlin compiler
val actuallObj = listOf("a", "b")
actually, the type is List<String>
val actuallObj: List<String> = listOf("a", "b")
actually, you’re actually removing type information with your syntax 😅

[Matteo Mirk]

You can’t for the list as a whole, but with reflection you can actually retrieve the runtime type of each element.

[Steven Wang]

Thanks for helping out guys!! yes, I end up just check first element in my list as I knew I added them with same type. That worked out for me

[nanodeath]

if that works, great 👍 watch out for polymorphic types

[Matteo Mirk]

@Steven Wang Just out of curiosity: if you have all elements of the same type, why can’t you declare the list with a bounded type parameter? Like List<String> ?

[Steven Wang]

I was using krangl, one of the column I put in data with type LocalDateTime krangl dataframe will assign it as AnyCol, it will be convenient to know which column is LocaldateTime which I can convert to ZonedDateTime and plot as x-axis

[Matteo Mirk]

Oh I see, you’re constrained by a library. Thanks for explaining