Hi all. What will be the kotlin collection functi...

# android

[Adnan Ali]

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]" ]

[Dominaezzz]

Can you outline the output type you're expecting? Map<String, String> ?

[Adnan Ali]

Map<String, List<String>>

[Dominaezzz]

I believe you're looking for associate .

[Dominaezzz]

Just change you outer map with associate .

[Adnan Ali]

Let me try associate

[Adnan Ali]

if (it.is_original==true) it.title

But this if check is still bypassing, I just want to return list of those pack which have flag is_original= true

[Dominaezzz]

Use filter.

[FranSoto]

it's a gold rule: First filtering then mapping

[Adnan Ali]

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

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

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 }
  }
}

[Adnan Ali]

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