How to convert Array<MutableSet<String>?> to IntArray

Question

Error:

Type mismatch: inferred type is Array<MutableSet<String>?> but IntArray was expected

Code:

  fun tab10(): IntArray {
        var Arr1 = arrayOf(player.chart_keys)
        return Arr1
  }

chart_keys is in a different class Player

var chart_keys: MutableSet<String>? = mutableSetOf(),

Is it possible?

arrayOf will create an array of whatever you pass into it. Therefore, passing a MutableSet<String>into it will create array of MutableSet<String> — Vladyslav Matviienko
– Vladyslav Matviienko, Commented Sep 27, 2019 at 10:34
kotlin can't predict how exactly you want to convert set of Strings to array of Integers.Therefore you have to tell it explicitly (by implementing manually) — Vladyslav Matviienko
– Vladyslav Matviienko, Commented Sep 27, 2019 at 10:50
What is chart_keys? Why does it have a _ instead of K? Why is the set mutable? Can it be immutable? — EpicPandaForce
– EpicPandaForce, Commented Sep 27, 2019 at 13:16

charles-allen · Accepted Answer · 2019-09-27 13:02:58Z

3

You need to map Strings to Ints and then convert the Set to an IntArray. This might work:

player.chart_keys?.map { it.toInt() }?.toIntArray()
   ?: intArrayOf()

edited Sep 27, 2019 at 13:02

answered Sep 27, 2019 at 12:51

charles-allen

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3 Comments

Quinn Over a year ago

I think it would be player.chart_keys?.map { it.toInt() }.toIntArray(), and I'm not sure if ones better than the other but instead of intArrayOf() I would use emptyArray()

charles-allen Over a year ago

Good catch! You'll notice in my edit that I only spotted it was nullable after writing that line! Fixing now :) Are sure emptyArray() can create an IntArray?

Quinn Over a year ago

ah, you're right - emptyArray() makes a Array<Int> - just ignore the second half of my comment

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