Declaring and Initializing Kotlin Lists

List

Create a list with listOf(). Unlike arrays, whose size is fixed, lists can add and remove elements with .add() and .remove(). However, arrays can change values with nums[1] = 123, while lists cannot change values with nums[1] = 222.

fun main() {
    val nums = listOf(1, 2, 3)
    val cols = listOf("Red", "Green", "Blue")

    for (n in nums) { println(n) }
    for (c in cols) { println(c) }
}

Output:

1
2
3
Red
Green
Blue

Key Functions

filter Function

As shown below, you can apply a filter to a list and extract elements that match the even-number condition.

fun main() {
    val nums = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
    println(nums.filter { it % 2 == 0 })
}

Output:

[2, 4, 6, 8, 10]