I am trying to understand the code snippet below(removed some not relevant bits). When ‘status’ is c...

# getting-started

[Tamas Szigeti]

I am trying to understand the code snippet below(removed some not relevant bits).
When ‘status’ is called, why is ‘toString(): String’ function called too? What calls it?

data class *ParkingLot*(*val* size: Int) {
data class *Car*(*val* plate: String, *val* color: String) {
override fun *toString*() = "$plate $color"
}

data class *Spot*(*val* spotNumber: Int, *val* isFree: Boolean, *val* car: Car?) {
override fun *toString*() = "$spotNumber $car"
}

private *val* parkingData = Array(size) { Spot(it + 1, *true*, *null*) }

*init* {
*if* (size != 0) println("Created a parking lot with $size spots.")
}

override fun *toString*(): String {
*val* str = parkingData.filter { !it.isFree }.joinToString("\n") { it.toString() }
return *when* {
size == 0 -> "Sorry, a parking lot has not been created."
str.isEmpty() -> "Parking lot is empty."
*else* -> str
}
}
}

fun *main*() {
*var* parkingLot = ParkingLot(0)
*while* (*true*) {
*val* command = readLine()!!.split(" ")
*when* (command[0]) {
"create" -> parkingLot = ParkingLot(command[1].toInt())
//"park" -> parkingLot.park(ParkingLot.Car(command[1], command[2]))
//"leave" -> parkingLot.leave(command[1].toInt())
"status" -> println(parkingLot)
"exit" -> *return*
}
}
}
If it is not the correct channel, which channel would it be?

[Goetz Markgraf]

In your when statement, there is a status case. In this case, you explicitly call println with the instance of ParkingLot . This class decends from Any which is Object in Java (more or less).
println(Object) calls toString on the object. That’s why this is called.