Careeroza

Mutable Lists

mutableListOf

Example

A MutableList can add, remove and replace elements.

fun main() {
    val cart = mutableListOf("Milk", "Bread")
    cart.add("Eggs")
    cart.add(0, "Butter")         // insert at index 0
    println(cart)

    cart.remove("Bread")
    cart.removeAt(0)
    println(cart)

    cart[0] = "Toned Milk"        // replace
    cart += "Curd"                // same as add
    println(cart)
    println("Items: ${cart.size}")

    cart.clear()
    println(cart.isEmpty())
}

Output

[Butter, Milk, Bread, Eggs]
[Milk, Eggs]
[Toned Milk, Eggs, Curd]
Items: 3
true

Building a List in a Loop

Example

Start with an empty mutable list and fill it. For an empty list you must give the element type.

fun main() {
    val evens = mutableListOf<Int>()
    for (n in 1..10) {
        if (n % 2 == 0) evens.add(n)
    }
    println(evens)
    println("Sum: ${evens.sum()}, max: ${evens.max()}")

    val names = MutableList(3) { "Player ${it + 1}" }
    println(names)
}

Output

[2, 4, 6, 8, 10]
Sum: 30, max: 10
[Player 1, Player 2, Player 3]