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Kotlin Arrays


Kotlin Arrays

Arrays are used to store multiple values in a single variable, instead of creating separate variables for each value.

To create an array, use the arrayOf() function, and place the values in a comma-separated list inside it:

val cars = arrayOf("Volvo", "BMW", "Ford", "Mazda")

Access the Elements of an Array

You can access an array element by referring to the index number, inside square brackets.

In this example, we access the value of the first element in cars:

Example

val cars = arrayOf("Volvo", "BMW", "Ford", "Mazda")
println(cars[0])
// Outputs Volvo
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Note: Just like with Strings, Array indexes start with 0: [0] is the first element. [1] is the second element, etc.


Change an Array Element

To change the value of a specific element, refer to the index number:

Example

cars[0] = "Opel"

Example

val cars = arrayOf("Volvo", "BMW", "Ford", "Mazda")
cars[0] = "Opel"
println(cars[0])
// Now outputs Opel instead of Volvo
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Array Length / Size

To find out how many elements an array have, use the size property:

Example

val cars = arrayOf("Volvo", "BMW", "Ford", "Mazda")
println(cars.size)
// Outputs 4
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Check if an Element Exists

You can use the in operator to check if an element exists in an array:

Example

val cars = arrayOf("Volvo", "BMW", "Ford", "Mazda")
if ("Volvo" in cars) {
  println("It exists!")
} else {
  println("It does not exist.")
}
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Loop Through an Array

Often when you work with arrays, you need to loop through all of the elements.

You can loop through the array elements with the for loop, which you will learn even more about in the next chapter.

The following example outputs all elements in the cars array:

Example

val cars = arrayOf("Volvo", "BMW", "Ford", "Mazda")
for (x in cars) {
  println(x)
}
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