JuniorTheoryCommon

What does the program print (lines separated by spaces)?

KOTLIN

fun main() {
    val ages = mapOf("Ann" to 30, "Bob" to 25)
    println(ages["Ann"])
    println(ages["Eve"])
}

30 null

Expecting an exception, as with a list index past the end: [] on a map returns null for a missing key, and only getValue throws NoSuchElementException.
Expecting 0 for a missing number: null means the map holds nothing under "Eve"; getOrDefault("Eve", 0) or ?: 0 gives a zero.

JuniorTheoryCommon

KOTLIN

fun main() {
    val ages = mapOf("Ann" to 30, "Bob" to 25)
    println(ages["Ann"])
    println(ages["Eve"])
}

30 null

Expecting an exception, as with a list index past the end: [] on a map returns null for a missing key, and only getValue throws NoSuchElementException.
Expecting 0 for a missing number: null means the map holds nothing under "Eve"; getOrDefault("Eve", 0) or ?: 0 gives a zero.