Kotlin getter / setter when using a primary constructor

Question

The example is from a Kotlin-course I'm doing:

class Car {
    var speed: Int = 0
        get() = field 
        set(value) {
            field = value
        }
}

If I like to use a primary constructor like this:

class Car(var speed: Int)

How would I have to write the getter / setter in that case?

Answer 1

You cannot write getters/setters inside of the constructor, you can do the following:

1. Create variable inside class whose value taken from constructor.

class Car(speed: Int) {
    var speed = speed
        get() = field 
        set(value) {
            field = value
        }
}

2. Use @JvmField annotation to restrict compiler not to auto-generate getters/setters and implement one yourself

class Car(@JvmField private var speed: Int) {
    fun getSpeed() = speed
    fun setSpeed(value: Int) { speed = value }
}