What s the best way to go from a `Stream lt T gt ` to a type kotlinlang #announcements

What's the best way to go from a `Stream<T>`...

javaru

08/21/2019, 3:08 PM

What's the best way to go from a

Stream<T>

to a typed array of

Array<T>

? I need to convert a

Map<String,String>

to an

Array<Pair<String,String>>

. I've done this as follows:

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val array: Array<Pair<String, String>> = myMap.entries.stream().map {
        Pair(it.key, it.value)
    }.toList().toTypedArray()

Is that the most efficient way? It seems like converting to a

List

first and then to the (typed)

Array

has an extra step. But I'm not seeing any other way to go from the

Stream<Pair<String,String>>

coming out of the

map{}

function to a typed

Array<Pair<String,String>>

(since

Stream.toArray()

would give me an untyped Array of

Array<Any>

ilya.gorbunov

08/21/2019, 3:11 PM

You don't need

stream

here at all: use

map.entries.toTypedArray()

➕ 1

👍 1

javaru

08/21/2019, 3:13 PM

Cool, thanks. Didn't know about that function (obviously).

ilya.gorbunov

08/21/2019, 3:16 PM

Oh, I see that you need an array of pairs, not an array of entries. Then

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val entryIterator = map.entries.iterator()
    val pairs = Array(map.size) { entryIterator.next().toPair() }

would be most efficient way. Not very fluent, though, and not recommended to use with concurrent maps.

javaru

08/21/2019, 3:17 PM

Thanks, I was just about to follow up that I needed the

Pair

(as I'm calling a function from a library that takes a

vararg Pair<String, String>

)

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