Kotlin Array Length: Everything to Know

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In almost all programming languages, an array is one of the most basic types of data structures. Kotlin array length is a critical attribute that lets you know how many elements are kept in an array. It is reachable via the size property, making it a quick and effective way to learn about the Array’s dimensions.

The topics of Overview on Array, Kotlin Array Creation, Basic Array Type in Kotlin, Obtain and Change an Array’s Elements, and Kotlin Array Length will all be covered in depth in this article.

Programmers organize data using arrays so that it is simple to sort or search for a related collection of items.

This article will teach you how to use the size property of the Array class or the count() function of the Array class to determine Kotlin array length.

Check this out: Kotlin Tutorial: Add New Element To Array

Overview of Kotlin Array Length

In a single variable, such as an integer or String, numerous objects of the same data type can be stored using arrays under a single variable name.

Kotlin Array Length

For instance, if we need to record the names of 1000 workers, we may declare an array of strings with a max size of 1000 rather than defining 1000 distinct string parameters.

Kotlin has a comprehensive set of array characteristics and supports methods to handle arrays, much like any other contemporary programming language.

Kotlin Array Creation

Using Kot lin’s arrayOf() method, we can generate an array and then add values to it in a comma-separated list:

val cars = arrayOf("AMG", "Mercedes", "Brabus", "GT")

The following data types are available as an option:

val fruits = arrayOf< String>("AMG", "Mercedes", "Brabus", "GT")

Alternatively, an array of null items of a specified size may be created using the arrayOfNulls() method.

Basic Array Type in Kotlin

Additionally, Kotlin has additional factory methods for building arrays of basic data types. As an illustration, the factory method for producing an integer array is:

val num = intArrayOf(1, 2, 3, 4)

Additional factory techniques for building arrays include:

  1. byteArrayOf()
  2. charArrayOf()
  3. shortArrayOf()
  4. longArrayOf()

Obtain and Change an Array’s Elements

The index number confined in square brackets can be used to retrieve a specific array member. The index of a Kotlin array begins at zero. Therefore, you must use three as the index to access the fourth member of the Array.


fun main(args: Array<String>) {

val fruits = arrayOf< String>("Apple", "Mango", "Banana", "Orange")

println( fruits [0]) println( fruits [3])


Additionally, Kotlin has the get() and set() member methods to retrieve and modify the data at a certain index.

Check out the sample below:


fun main(args: Array<String>) {

val fruits = arrayOf< String>("Apple", "Mango", "Banana", "Orange")

println( fruits.get(0))

println( fruits.get(3))

// Set the value at 3rd index

fruits.set(3, "Guava")

println( fruits.get(3))


Kotlin Array Length

The various methods for determining an array’s or list’s size in Kotlin are examined in this section.

Applying size method

In Kotlin, employing the size property of an array or list is the default way to determine their size. The following shows how this is done for a List and an IntArray Kotlin:


fun main() {

val array = IntArray(4)

val array_size = array.size

println(array_size) // 4

val list = listOf(1, 2, 3, 4, 5)

val list_size = list.size

println(list_size) // 5


Applying the method count()

Employing the count() method with the condition set to true is another alternative for counting the number of entries in an array or list. This would convert into the following shortcode:


fun main() {

val array = arrayOf(1, 2, 3)

val array_size = array.count { true }

println(array_size) // 3

val list = listOf("A", "B", "C", "D")

val list_size = list.count { true }

println(list_size) // 4


Applying Reflection

We can use java.lang to access an array’s properties dynamically, although this is not advised.the class reflect.Array. Utilize the getLength() method to determine an array’s length. Keep in mind that this only functions for arrays; otherwise, java.lang will be produced. The argument is not an array: IllegalArgumentException.


fun main() {

val array = arrayOfNulls<Int>(5)

val array_size = java.lang.reflect.Array.getLength(array)

println(array_size) // 5


Employing Array.size to verify an empty array

Array.size may also determine if an array has at least one element. The Array is empty if Array.size returns 0, and it is not empty if it returns a value larger than 0.


val employees = arrayOf("John", "Jacob", "Martha", "Neel")

if (employees.size > 0) {

println("Array is not empty")

} else {

println("Array is empty")


Output: Array is not empty

In the earlier code, an array of workers was constructed using employees.size, we are determining whether or not the provided Array is empty.

For empty Array. E.g.

val arr = arrayOf<String>()

if (arr.size > 0) {

println("Array is not empty")

} else {

println("Array is empty")


Output: Array is empty

Read also: Kotlin Parameterized Test: What Is It?


What is Kotlin Array length?

Kotlin Array length refers to the number of elements in an array. You can access it using the size property.

How can I find the length of a Kotlin Array?

To find the length of a Kotlin Array, simply use the size property, like this: Array.size.

Is the length of a Kotlin Array fixed?

No, the length of a Kotlin Array is not fixed and can change dynamically as you add or remove elements from it.

Can I change the length of a Kotlin Array?

Yes, you can change the length of a Kotlin Array by adding or removing elements using methods like add or removeAt.

What's the time complexity of getting the length of a Kotlin Array?

The time complexity of getting the length of a Kotlin Array is O(1), which means it's a constant-time operation, regardless of the Array's size.


Depending on the size of the Array, you might need to utilize the Kotlin array length property several times in your code. The Array’s length is essential information for your program’s decision-making, whether you’re conducting computations, iterating across items, or verifying input.

In conclusion, a key component of working with arrays is the Kotlin array length, obtained through the size property. Its dynamic nature and quick access times give developers the tools to create flexible, high-performing apps that adjust to changing data needs.

See also: Copy Array In JavaScript: Efficient Data Duplication Techniques

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