How to convert String array to Int array in Kotlin?

I'd use something simple like

val strings = arrayOf("1", "2", "3")
val ints = ints.map { it.toInt() }.toTypedArray()

Alternatively, if you're into extensions:

fun Array<String>.asInts() = this.map { it.toInt() }.toTypedArray()

strings.asInts()

If you are trying to convert a List structure that implements RandomAccess (like ArrayList, or Array), you can use this version for better performance:

IntArray(strings.size) { strings[it].toInt() }

This version is compiled to a basic for loop and int[]:

int size = strings.size();
int[] result = new int[size];
int index = 0;

for(int newLength = result.length; index < newLength; ++index) {
    String numberRaw = strings.get(index);
    int parsedNumber = Integer.parseInt(numberRaw);
    result[index] = parsedNumber;
}

If you use Array.map as other answers suggest, you get back a List, not an Array. If you want to map an array strings to another array results, you can do it directly like this:

val results = Array(strings.size) { strings[it].toInt() }

This is more efficient than first mapping to a List and then copying the elements over to an Array by calling .toTypedArray().

Consider the input like this "" (empty string)

It would be better to do the filtering first. And it is true the return value is list but not array.

If you need an array, add .toTypedArray() or .toIntArray().

    fun stringToIntList(data: String): List<Int> =
            data.split(",").filter { it.toIntOrNull() != null }
                    .map { it.toInt() }

val result = "[1, 2, 3, 4, 5]".removeSurrounding("[","]").replace(" ","").split(",").map { it.toInt() }

Found following simplest

strings.chars().toArray()