setOf filtering using a list in Kotlin

Question

I'm trying to make a filtering in a list by another list of Values Ex

I want to make this

  selectedAreasList = ListOf(1,2,3)

  initialItemProductList.filter { it.areaId in setOf(selectedAreasList) }

instead

  initialItemProductList.filter { it.areaId in setOf(1,2,3) }

Because I don't know the number of items that my list will have

You don't strictly need a set to call in; it would work with in selectedAreasList directly. But most Set implementations are much more efficient at this (as they can look up the hash code directly instead of scanning through each time), so it's usually a good idea. — gidds
– gidds, Commented Nov 21, 2020 at 21:17

Aplet123 · Accepted Answer · 2020-11-21 20:05:37Z

1

Instead of using setOf on a list, use the existing toSet function defined for all Sequences:

selectedAreasList = listOf(1, 2, 3)
// make a set before the filter to avoid repeatedly making a set
selectedAreasSet = selectedAreasList.toSet()
initialItemProductList.filter { id.areaId in selectedAreasSet }

answered Nov 21, 2020 at 20:05

Aplet123

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2 Comments

Antonio Labra Over a year ago

like a charm... Thanks dude

Animesh Sahu Over a year ago

I think you've mis spelled collection with sequence, although it is defined for sequences as well :)

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