Kotlin Programming: The Big Nerd Ranch Guide, 2nd Edition

Implementing an Interface

To use an interface, we say that you “implement” it on a class. There are two parts to this: First, you declare that the class implements the interface. Then, you must ensure that the class provides implementations for all the properties and functions specified in the interface.

Use the : operator to implement the Fightable interface on Player.

Listing 17.2  Implementing an interface (Player.kt)

class Player(
    initialName: String,
    val hometown: String = "Neversummer",
    override var healthPoints: Int,
    val isImmortal: Boolean
) : Fightable {

    override var name = initialName
        get() = field.replaceFirstChar { it.uppercaseChar() }
        private set(value) {
            field = value.trim()
        }
    ...
}

(We will explain the override ...