Which do you prefer? 1️⃣

for (index in 0 until itemCount) {

2️⃣

repeat(itemCount) { index ->

I’d say it depends on the use case, if the index represents something like a position I would use 1, but if it’s only used as the current iteration of the loop I would use 2

Yes, I'd say it depends on what you want to express. Use

repeat

if you want to repeat something multiple times. Use

forEach

or

forEachIndexed

if you want to iterate a collection. I rarely ever use explicit

for

loops

I should probably have mentioned that, here, an

index

refers to an item index in a list (but we do not have direct access to that list, otherwise we would just use

forEachIndexed

)

Could you please share a bit more about how you use that loop, then?

Any API that accepts a position (in a list) as a function arg. For example,

getItemId

in

RecyclerView.Adapter

In my particular case (not using that exact function) I have:

for (position in 0 until itemCount) {
    val item = itemAtPosition(position)
    if (item is Foo) {
        notifyItemChanged(position)
    }
}

if it's over a list, I would definitely write

for (index in list.indices) {

Ok, but in this case there is no direct access to the list

Kind of related: turns out collection operators create a lot of garbage (gc) if used often, e.g. in render loops like jetpack compose where regular for loops will not. Most of the time you'd want to prioritize readability though.

compose has internal helpers that avoid allocating, https://github.com/androidx/androidx/blob/androidx-main/compose/ui/ui-util/src/commonMain/kotlin/androidx/compose/ui/util/ListUtils.kt

Exactly

Also if you need to use

continue

in your loop body, you can't use

repeat

.