How to initialize an array in Kotlin with values?

In Java an array can be initialized such as:

int numbers[] = new int[] {10, 20, 30, 40, 50}

How does Kotlin's array initialization look like?

val numbers: IntArray = intArrayOf(10, 20, 30, 40, 50)

See Kotlin - Basic Types for details.

You can also provide an initializer function as a second parameter:

val numbers = IntArray(5) { 10 * (it + 1) }
// [10, 20, 30, 40, 50]

Worth mentioning that when using kotlin builtines (e.g. intArrayOf(), longArrayOf(), arrayOf(), etc) you are not able to initialize the array with default values (or all values to desired value) for a given size, instead you need to do initialize via calling according to class constructor.

// Array of integers of a size of N
val arr = IntArray(N)

// Array of integers of a size of N initialized with a default value of 2
val arr = IntArray(N) { i -> 2 }

In Kotlin There are Several Ways.

var arr = IntArray(size) // construct with only size

Then simply initial value from users or from another collection or wherever you want.

var arr = IntArray(size){0}  // construct with size and fill array with 0
var arr = IntArray(size){it} // construct with size and fill with its index

We also can create array with built in function like-

var arr = intArrayOf(1, 2, 3, 4, 5) // create an array with 5 values

Another way

var arr = Array(size){0} // it will create an integer array
var arr = Array<String>(size){"$it"} // this will create array with "0", "1", "2" and so on.

You also can use doubleArrayOf() or DoubleArray() or any primitive type instead of Int.

Here's an example:

fun main(args: Array<String>) {
    val arr = arrayOf(1, 2, 3);
    for (item in arr) {
        println(item);
    }
}

You can also use a playground to test language features.

How to initialize an array in Kotlin with values?

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