How to initialize an array in Kotlin with values?

Question

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 li

Answer 1

My answer complements @maroun these are some ways to initialize an array:

Use an array

val numbers = arrayOf(1,2,3,4,5)

Use a strict array

val numbers = intArrayOf(1,2,3,4,5)

Mix types of matrices

val numbers = arrayOf(1,2,3.0,4f)

Nesting arrays

val numbersInitials = intArrayOf(1,2,3,4,5)
val numbers = arrayOf(numbersInitials, arrayOf(6,7,8,9,10))

Ability to start with dynamic code

val numbers = Array(5){ it*2}

Answer 2

Kotlin language has specialised classes for representing arrays of primitive types without boxing overhead: for instance – IntArray, ShortArray, ByteArray, etc. I need to say that these classes have no inheritance relation to the parent Array class, but they have the same set of methods and properties. Each of them also has a corresponding factory function. So, to initialise an array with values in Kotlin you just need to type this:

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

...or this way:

val myArr = Array<Int>(5, { i -> ((i+1) * 10) })

myArr.forEach { println(it) }                                // 10, 20, 30, 40, 50

Now you can use it:

myArr[0] = (myArr[1] + myArr[2]) - myArr[3]