Inheritance and Interfaces

Interfaces

Implement a small interface with a class.

interface An interface names behavior that a class promises to provide.

Interfaces

title
Interfaces.kt
Replay: real traced execution (multi-file project)
interface Describable {
    fun describe(): String
}

class Task(val title: String) : Describable {
    override fun describe(): String {
        return "task:$title"
    }
}

fun main() {
    val title = "Build"
    val task = Task(title)
    val description = task.describe()

    println("title=$title")
    println("description=$description")
}

interface Describable {
    fun describe(): String
}

class Task(val title: String) : Describable {
    override fun describe(): String {
        return "task:$title"
    }
}

fun main() {
    val title = "Test"
    val task = Task(title)
    val description = task.describe()

    println("title=$title")
    println("description=$description")
}

interface Describable {
    fun describe(): String
}

class Task(val title: String) : Describable {
    override fun describe(): String {
        return "task:$title"
    }
}

fun main() {
    val title = "Ship"
    val task = Task(title)
    val description = task.describe()

    println("title=$title")
    println("description=$description")
}

  1. title ← Build

    11fun main() {12    val title→ Build = "Build" //@title="Test", "Ship"13    val task = Task(titleBuild)14    val description = task.describe()

  2. override fun describe(): String

    5class Task(val title: String) : Describable {6    override fun describe(): String {7        return "task:$titleBuild"8    }

  3. description ← task:Build

    13    val task = Task(title)14    val description→ task:Build = task.describe()1516    println("title=$titleBuild")17    println("description=$descriptiontask:Build")18}
    outputtitle=Build
description=task:Build

  1. title ← Test

    11fun main() {12    val title→ Test = "Test"13    val task = Task(titleTest)14    val description = task.describe()

  2. override fun describe(): String

    5class Task(val title: String) : Describable {6    override fun describe(): String {7        return "task:$titleTest"8    }

  3. description ← task:Test

    13    val task = Task(title)14    val description→ task:Test = task.describe()1516    println("title=$titleTest")17    println("description=$descriptiontask:Test")18}
    outputtitle=Test
description=task:Test

  1. title ← Ship

    11fun main() {12    val title→ Ship = "Ship"13    val task = Task(titleShip)14    val description = task.describe()

  2. override fun describe(): String

    5class Task(val title: String) : Describable {6    override fun describe(): String {7        return "task:$titleShip"8    }

  3. description ← task:Ship

    13    val task = Task(title)14    val description→ task:Ship = task.describe()1516    println("title=$titleShip")17    println("description=$descriptiontask:Ship")18}
    outputtitle=Ship
description=task:Ship