Google PlayGround

foldable-phone.kt

fun main() {
    val xaiomi = Foldable(isFolded=true, isScreenLightOn=false)
    xaiomi.checkPhoneScreenLight()
    xaiomi.switchOn()
    xaiomi.checkPhoneScreenLight()
    xaiomi.isFolded = false
    xaiomi.switchOn()
    xaiomi.checkPhoneScreenLight()
}
open class Phone(var isScreenLightOn: Boolean = false){
    open fun switchOn() {
        isScreenLightOn = true
    }
    
    fun switchOff() {
        isScreenLightOn = false
    }
    
    fun checkPhoneScreenLight() {
        val phoneScreenLight = if (isScreenLightOn) "on" else "off"
        println("The phone screen's light is $phoneScreenLight.")
    }
}
class Foldable(var isFolded: Boolean, isScreenLightOn: Boolean): Phone(isScreenLightOn) {

    override fun switchOn() {
        if(!isFolded) {
            super.switchOn()
        }
    }
}