Hi all. What will be the kotlin collection function to convert nested list into hashmap.

data class Products(id){
	packList=ArrayList<Packs>
}

data class Pack(title: string, is_original: Boolean)

val list= productList.map { it.id  to  it.packlist.map{ if (it.is_original==true} it.title}

Note: ArrayList<Products> But Products= Arraylist<Pack> i.e I want a hashmap just like this ["1" , "[item1, item2, item3, item4]" ]

Can you outline the output type you're expecting?

Map<String, String>

?

Map<String, List<String>>

I believe you're looking for

associate

.

Let me try

associate

Use filter.

it's a gold rule: First filtering then mapping

How do I filter first, because nested list is only accessible from outerList index i.e Products List ?

You can use

mapNotNull

to do a filter + map at the same time:

productList.associate { (id, packlist) ->
  id to packlist.mapNotNull { (title, isOriginal) ->
    title.takeIf { isOriginal }
  }
}

Thanks @Zach Klippenstein (he/him) [MOD]