Access to out bound elements of an Array in Kotlin

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Most of the logic i use to work on arrays in JavaScript depends on me being able to play with indexes. I am making the transition to kotlin ,so i have encountered that some of the logic i use doesn't fit kotlin.

Something as simple as initializing an Array and then accessing an undefined index seems to be more complicated than i am used to .

I understand that there are multiple ways of adding to lists on kotlin and accessing arrays and stuff. But what i want to know is What options do i have to Make arrays with unfixed Size and then add elements to the array in an indiscriminated order. I just took the udacity kotlin boot camp last week but i have been having issues when using indexes as i used in javascript.

// JavaScript Code
var W = Array();
W[0] = 1
//Kotlin 
var W = arrayOf()
W[0] =1

IndexOutofbounds Exception


In Kotlin, Arrays have a fixed size, unlike Lists which can grow and shrink as items are added or removed.

If you want to use a List (specifically, a MutableList), you could start with an empty one, and then append items to it as needed, e.g.:

val l = mutableListOf<Int>()
l += 1

Or you could use an Array, created with the appropriate size, e.g.:

val a = Array(10){ 0 }
a[0] = 1

However, that procedural idiom of first creating a structure and then iterating to fill it isn't needed as much in Kotlin, as there are often functional ways of creating the structure and initialising it in one go.

If you're creating a list from something you can iterate (e.g. a range, another list, an array, a String, or whatever), then you can use map():

val newList = (0..9).map{ it * 2 + 1 }

Or you can specify (how to calculate) array values when you create it:

val a = Array(10){ it * 2 + 1 }

(There are many more sophisticated possibilities, too!)

That style is often easier to read and maintain, as it concentrates more on what you're trying to do than how you do it.

getOrNull, Returns an element at the given index or null if the index is out of bounds of this array. Common. JVM. JS. Native. 1.0. fun <T> List<T>.getOrNull(index: Int): T? The [ ] operator can be used to access and modify arrays. To access an array element, the syntax would be: val x = num[1] This will assign the value of the second element in num to x. To modify an array element, we should do: num[2] = 5; This will change the value of the third element in the num array to 5.


If you want to convert a String to a byte array, Kotlin Std Lib already includes an extension fun for that

fun String.toByteArray(
    charset: Charset = Charsets.UTF_8
): ByteArray

// Example from Kotlin Docs
val charset = Charsets.UTF_8
val byteArray = "Hello".toByteArray(charset)
println(byteArray.contentToString()) // [72, 101, 108, 108, 111]
println(byteArray.toString(charset)) // Hello

Array, Returns the number of elements in the array. val size: Int. Functions. Groups elements of the original array by the key returned by the given keySelector function applied to each element and returns a map where each group key is associated with a list of corresponding elements. fun <T, K> Array<out T>.groupBy(. keySelector: (T) -> K. ): Map<K, List<T>>.


if you want to you arrayOf(), you have to init. try this,

val arr = arrayOf(1,2,3)
//arr[0] = 1
//arr[1] = 2
//arr[2] = 3

Also if an array element can have a null value or if the type of the element allows null values, then the arrayOfNulls <> () function must be used.

val arr1 = arrayOf(1,2,3)
val arr2 = arrayOfNulls<Int>(5)

Retrieving Single Elements, The first element has the position 0 , and the last one is (size - 1) . elementAt() is useful for collections that do not provide indexed access, or are not statically� A. Access elements of array in kotlin using indexing property. Let’s say we have an array (named arr) of size n. Each element in array has an index. Indexing in array starts from 0. For example, 1st position element has index 0, 2nd position element has index 1, 3rd position element has index 2 etc.


Collection Transformation Operations, It applies the given lambda function to each subsequent element and returns the list When called on a collection or an array with another collection (array) as an library functions that provide flat access to nested collection elements useful. This is because we are trying to access elements at 6th position but there are only 5 elements in array. We can only set value by using index or .set method. We can n’t add a new element in existing array in kotlin. Array in Kotlin are fixed size (Immutable). It means, once created it can not be resized.


Creating Enums with associated data using Sealed Classes in Kotlin , Creating Enums with associated data using Sealed Classes in Kotlin The idea is to use the powerful of the enum's associated values but class Outgoing(val status: DeliveryStatus) : Direction() } contentType is casted inside of the is clause, this allow us to access to specific fields being compile safety. Elements of array. Kotlin has set () and get () functions that can directly modify and access the particular element of the array respectively. In Kotlin Array, the get () function is used to get the elements from the specified index. The set () function is used to set element at particular index location.


Why am I getting array index out of bounds exception?, An array is not guaranteed to have a 0th element. Its perfectly legal to decla I will recommend you to please access your array like this. [code]. public class� Kotlin has set () and get () functions that can direct modify and access the particular element of array respectively. The set () function is used to set element at particular index location. This is also done with assigning element at array index. Array get () function is used to get element from specified index.