Kotlin - subclasses and superclasses - prefix(open、override)、functions、properties

Head First Kotlin
A Brain-Friendly Guide
楽天ブックス(Kobo) 紀伊國屋書店(Kinoppy)

開発環境

• macOS Mojave - Apple (OS)
• Windows 10 Pro (OS)
• IntelliJ IDEA CE(Community Edition) (IDE(統合開発環境))
• Kotlin (プログラミング言語)

Head First Kotlin: A Brain-Friendly Guide (Dawn Griffiths(著)、David Griffiths(著)、O'Reilly Media)のChapter 5(subclasses and superclasses - Using Your Inheritance)、Code Magnets(141)の解答を求めてみる。

コード

open class Animal {
    open val image = ""
    open val food = ""
    open val habitat = ""
    var hunger = 10

    open fun makeNoise() {
        println("The Animal is making a noise")
    }

    open fun eat() {
        println("The Animal is eating")
    }

    open fun roam() {
        println("The Animal is roaming")
    }
}

open class Canine : Animal() {
    override fun roam() {
        println("The Canine is roaming")
    }
}

class Wolf : Canine() {
    override val image: String = "wolf.jpg"
    override val food = "meat"
    override val habitat = "forests"
    override fun makeNoise() {
        println("Hooooowl!")
    }

    override fun eat() {
        println("The Wolf is eating $food")
    }
}

fun main() {
    val a = Animal()
    val c = Canine()
    val w = Wolf()

    a.makeNoise()
    a.eat()
    a.roam()
    println()
    c.makeNoise()
    c.eat()
    c.roam()
    println()
    w.makeNoise()
    w.eat()
    w.roam()
}

入出力結果

The Animal is making a noise
The Animal is eating
The Animal is roaming

The Animal is making a noise
The Animal is eating
The Canine is roaming

Hooooowl!
The Wolf is eating meat
The Canine is roaming

Process finished with exit code 0