[class / interface]

1. class

class Item(
    val name: String,
    val price: Int
)

val item = Item("Book", 10000)
println("item name is ${item.name}, price is ${item.price}")

 

2. interface

class Item(
    val name: String,
    val price: Int
) : ItemTrade {
    override fun buy() {
        println("[buy] $name")
    }

    override fun sell() {
        println("[sell] $name")
    }
}

interface ItemTrade {
    fun buy()
    fun sell()
}

val item = Item("Book", 10000)
println("item name is ${item.name}, price is ${item.price}")

item.buy()
item.sell()