getOrElse

getOrElse provides safe access to elements of a collection. It takes an index and a function that provides the default value in cases when the index is out of bound.

fun main() {

    val list = listOf(0, 10, 20)
    println(list.getOrElse(1) { 42 })    // 1
    println(list.getOrElse(10) { 42 })   // 2
}

1. Prints the element at the index 1.
2. Prints 42 because the index 10 is out of bounds.

getOrElse can also be applied to Map to get the value for the given key.

fun main() {

    val map = mutableMapOf<String, Int?>()
    println(map.getOrElse("x") { 1 })       // 1
    
    map["x"] = 3
    println(map.getOrElse("x") { 1 })       // 2
    
    map["x"] = null
    println(map.getOrElse("x") { 1 })       // 3
}

1. Prints the default value because the key "x" is not in the map.
2. Prints 3, the value for the key "x".
3. Prints the default value because the value for the key "x" is not defined.