JuniorTheoryCommon

What does the program print?

KOTLIN

object Counter {
    var count = 0
}

fun main() {
    val a = Counter
    val b = Counter
    a.count += 1
    b.count += 1
    println(Counter.count)
}

Expecting 1: thinking val b = Counter makes a second object. An object has one instance, so a and b both name it and share one count.
Expecting 0: thinking a and b are copies and Counter stays untouched. They are names for the object itself, so its count is 2.

What does println(a === b) print?
When is the single Counter object created?

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JuniorTheoryCommon

What does the program print?

KOTLIN

object Counter {
    var count = 0
}

fun main() {
    val a = Counter
    val b = Counter
    a.count += 1
    b.count += 1
    println(Counter.count)
}

Expecting 1: thinking val b = Counter makes a second object. An object has one instance, so a and b both name it and share one count.
Expecting 0: thinking a and b are copies and Counter stays untouched. They are names for the object itself, so its count is 2.

What does println(a === b) print?
When is the single Counter object created?

Back to questions Open topic in roadmap →Answer it yourself — Quiz