Kotlinのオブジェクト式を使った無名クラスの作成方法と活用例

val instance = object : InterfaceName {
    override fun method() {
        println("This is an anonymous class implementation.")
    }
}

interface Greeter {
    fun greet()
}

fun main() {
    val greeter = object : Greeter {
        override fun greet() {
            println("Hello from the anonymous class!")
        }
    }
    greeter.greet()
}

Hello from the anonymous class!

open class Animal {
    open fun sound() {
        println("Animal makes a sound")
    }
}

fun main() {
    val dog = object : Animal() {
        override fun sound() {
            println("Woof! Woof!")
        }
    }
    dog.sound()
}

Woof! Woof!

fun main() {
    object {
        fun printMessage() {
            println("This is a message from an anonymous object.")
        }
    }.printMessage()
}

This is a message from an anonymous object.

button.setOnClickListener(object : View.OnClickListener {
    override fun onClick(v: View?) {
        println("Button clicked!")
    }
})

fun fetchData(callback: Callback) {
    callback.onSuccess("Data fetched successfully!")
}

fetchData(object : Callback {
    override fun onSuccess(result: String) {
        println(result)
    }

    override fun onError(error: String) {
        println("Error: $error")
    }
})

open class Animal {
    open fun sound() {
        println("Animal makes a sound")
    }
}

val specialAnimal = object : Animal() {
    override fun sound() {
        println("Special Animal says: Meow!")
    }
}

specialAnimal.sound()

val singleton = object {
    val name = "Singleton"
    fun printName() {
        println(name)
    }
}

singleton.printName()

Singleton

val mockService = object : Service {
    override fun fetchData(): String {
        return "Mock data for testing"
    }
}

println(mockService.fetchData())

interface Printer {
    fun printMessage()
}

fun main() {
    val printer = object : Printer {
        override fun printMessage() {
            println("Hello, this is an anonymous class implementing Printer!")
        }
    }
    printer.printMessage()
}

Hello, this is an anonymous class implementing Printer!

interface Calculator {
    fun add(a: Int, b: Int): Int
    fun subtract(a: Int, b: Int): Int
}

fun main() {
    val calculator = object : Calculator {
        override fun add(a: Int, b: Int): Int {
            return a + b
        }

        override fun subtract(a: Int, b: Int): Int {
            return a - b
        }
    }
    println("Addition: ${calculator.add(10, 5)}")
    println("Subtraction: ${calculator.subtract(10, 5)}")
}

Addition: 15  
Subtraction: 5

interface ClickListener {
    fun onClick()
}

fun main() {
    val buttonClickListener = object : ClickListener {
        override fun onClick() {
            println("Button was clicked!")
        }
    }

    // 仮のボタンイベント呼び出し
    buttonClickListener.onClick()
}

Button was clicked!

open class Animal {
    open fun makeSound() {
        println("Some generic animal sound")
    }
}

fun main() {
    val cat = object : Animal() {
        override fun makeSound() {
            println("Meow! Meow!")
        }
    }

    cat.makeSound()
}

Meow! Meow!

open class Vehicle {
    open fun start() {
        println("Vehicle is starting...")
    }

    open fun stop() {
        println("Vehicle is stopping...")
    }
}

fun main() {
    val sportsCar = object : Vehicle() {
        override fun start() {
            println("Sports car is roaring to life!")
        }

        override fun stop() {
            println("Sports car is screeching to a halt!")
        }
    }

    sportsCar.start()
    sportsCar.stop()
}

Sports car is roaring to life!  
Sports car is screeching to a halt!

abstract class Shape {
    abstract fun draw()
}

fun main() {
    val circle = object : Shape() {
        override fun draw() {
            println("Drawing a circle")
        }
    }

    circle.draw()
}

Drawing a circle

open class Logger {
    open fun log(message: String) {
        println("Log: $message")
    }
}

fun main() {
    val specialLogger = object : Logger() {
        override fun log(message: String) {
            println("Special Log: $message")
        }
    }

    specialLogger.log("This is a custom log message")
}

Special Log: This is a custom log message

interface Greeter {
    fun greet()
}

fun main() {
    val greeter = object : Greeter {
        override fun greet() {
            println("Hello from an object expression!")
        }
    }
    greeter.greet()
}

Hello from an object expression!

fun main() {
    val greeter: () -> Unit = { println("Hello from a lambda expression!") }
    greeter()
}

Hello from a lambda expression!

fun main() {
    for (i in 1..3) {
        val instance = object {
            fun sayHello() {
                println("Hello, this is instance $i")
            }
        }
        instance.sayHello()
    }
}

val instance = object {
    fun sayHello() {
        println("Hello, this is a reusable instance")
    }
}

fun main() {
    for (i in 1..3) {
        instance.sayHello()
    }
}

fun setListener(listener: () -> Unit) {
    listener()
}

fun main() {
    setListener(object : Runnable {
        override fun run() {
            println("Running task")
        }
    })
}

fun setListener(listener: () -> Unit) {
    listener()
}

fun main() {
    setListener { println("Running task") }
}

val instance = object {
    var count = 0
    fun increment() {
        count++
        println("Count: $count")
    }
}

fun main() {
    instance.increment()
    instance.increment()
}

fun process() {
    val instance = object : Processor {
        override fun processTask() {
            println("Processing...")
            // 多くの処理がここに続く...
        }
    }
    instance.processTask()
}

class TaskProcessor : Processor {
    override fun processTask() {
        println("Processing...")
        // 他の処理を記述
    }
}

fun main() {
    val processor = TaskProcessor()
    processor.processTask()
}

object SingletonProcessor {
    fun process() {
        println("Processing with singleton instance")
    }
}

fun main() {
    SingletonProcessor.process()
}

interface ClickListener {
    fun onClick()
    fun onLongClick()
}

fun main() {
    val buttonClickListener = object : ClickListener {
        override fun onClick() {
            println("Button was clicked!")
        }

        override fun onLongClick() {
            println("Button was long-clicked!")
        }
    }

    // イベントリスナーの呼び出し
    buttonClickListener.onClick()
    buttonClickListener.onLongClick()
}

Button was clicked!  
Button was long-clicked!

val button = Button(context) // 仮のボタン
button.setOnClickListener(object : View.OnClickListener {
    override fun onClick(v: View?) {
        println("Button clicked in Android!")
    }
})

interface DataListener {
    fun onDataReceived(data: String)
}

fun fetchData(listener: DataListener) {
    // データ取得のシミュレーション
    listener.onDataReceived("Sample data fetched")
}

fun main() {
    fetchData(object : DataListener {
        override fun onDataReceived(data: String) {
            println("Received data: $data")
        }
    })
}

Received data: Sample data fetched

interface AlarmListener {
    fun triggerAlarm()
}

fun main() {
    val normalAlarm = object : AlarmListener {
        override fun triggerAlarm() {
            println("Normal alarm triggered!")
        }
    }

    val silentAlarm = object : AlarmListener {
        override fun triggerAlarm() {
            println("Silent alarm activated!")
        }
    }

    // 状況に応じて異なるリスナーを呼び出し
    normalAlarm.triggerAlarm()
    silentAlarm.triggerAlarm()
}

Normal alarm triggered!  
Silent alarm activated!