なんとなくkotlinで書き直してみる

まだよくわかってないけどkotlinしてみる

import javafx.stage.Stage
import javafx.application.Application

import javafx.scene.Scene
import javafx.scene.control.Button
import javafx.scene.layout.BorderPane

import javafx.event.ActionEvent
import javafx.event.EventHandler

import javafx.animation.KeyFrame
import javafx.animation.Timeline
import javafx.animation.Animation

import javafx.util.Duration

import javax.sound.midi.Receiver
import javax.sound.midi.MidiSystem
import javax.sound.midi.ShortMessage

import javax.sound.midi.InvalidMidiDataException

fun main(args: Array<String>){
    Application.launch(DrumTest::class.java, *args)
}

class DrumTest() : Application(){
    private val receiver: Receiver
    
    private val pattern = "B-S-BBS-"
    private var patternIndex = 0
    
    init{
        receiver = MidiSystem.getReceiver()
    }
    
    override fun start(stage: Stage){
        val button = createDrumButton("8ビート！")
        val pane = BorderPane()
        
        pane.setCenter(button)
        
        val scene = Scene(pane, 320.0, 120.0)
        
        stage.setScene(scene)
        stage.show()
    }
    
    private fun createDrumButton(text: String): Button{
        val button = Button(text)
        
        val timer = Timeline(KeyFrame(Duration.millis(250.0), object : EventHandler<ActionEvent>{
            override fun handle(event: ActionEvent?){
                try{
                    if(pattern[patternIndex] == 'B'){
                        noteBassDrum();
                    }else if(pattern[patternIndex] == 'S'){
                        noteSnareDrum();
                    }
                }catch(ex: InvalidMidiDataException){
                    ex.printStackTrace();
                }

                patternIndex = (patternIndex + 1) % 8;
            }
        }))
        
        button.setOnAction({ _ ->
            if(timer.getStatus() == Animation.Status.STOPPED){
                timer.setCycleCount(16);
                timer.play();
            }
        })
        
        return button
    }
    
    private fun noteBassDrum(){
        val message = ShortMessage()
        message.setMessage(ShortMessage.NOTE_ON, 9, 36, 100)
        receiver.send(message, -1)
    }
    
    private fun noteSnareDrum(){
        val message = ShortMessage()
        message.setMessage(ShortMessage.NOTE_ON, 9, 38, 100)
        receiver.send(message, -1)
    }
}

参考
qiita.com