Реализации на Kotlin

Command

Общая реализация на языке Kotlin

ICommand

fun interface ICommand {
    operator fun invoke()
}

CopyCommand

class CopyCommand : ICommand {
    override operator fun invoke() {
        println("Copying document.")
    }
}

PrintCommand

class PrintCommand : ICommand {
    override operator fun invoke() {
        println("Printing document.")
    }
}

ScanCommand

class ScanCommand : ICommand {
    override operator fun invoke() {
        println("Scanning document.")
    }
}

Invoker

class Invoker(var command: ICommand) {
    fun execute() {
        println("Executing...")
        command()
    }
}

fun main() {
    val copyCommand = CopyCommand()
    val scanCommand = ScanCommand()
    val printCommand = PrintCommand()

    val printer = Invoker(copyCommand)
    printer.execute()

    printer.command = scanCommand
    printer.execute()

    printer.command = printCommand
    printer.execute()
}