为什么这个Java程序的滑块不起作用？

Question

这是一个粉丝程序，使用滑块来增加和降低风扇的速度。我不需要增加和减少按钮，我只有它们作为指导，以帮助滑块找出向左或向右滚动时会发生什么。我稍后会删除它们。我的滑块没有显示，我无法测试。我在哪里错了？

import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Arc;
import javafx.scene.shape.ArcType;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;
import javafx.util.Duration;
import javafx.scene.control.Slider;


public class module2 extends Application {

   @Override
    public void start(Stage primaryStage) throws Exception {

        // Create fan pane
        FanPane fanPane = new FanPane(100);

        Slider mSlider = new Slider();
        HBox scrollPane = new HBox(mSlider);

        KeyFrame keyFrame = new KeyFrame(Duration.millis(10), e-> fanPane.spin());

        Timeline fanTimeline = new Timeline(keyFrame);
        fanTimeline.setCycleCount(Timeline.INDEFINITE);

        // Buttons pause, resume, increase, decrease, reverse
        Button pause = new Button("Pause");
        pause.setOnAction(e-> fanTimeline.pause());

        Button resume = new Button("Resume");
        resume.setOnAction(e-> fanTimeline.play());

        //fanPane.increase()
        Button increase = new Button("Increase");
        increase.setOnAction(e -> {
            fanTimeline.setRate(fanTimeline.getCurrentRate() + 1);
            mSlider.setValue(fanTimeline.getCurrentRate());
        });

        Button decrease = new Button("Decrease");
        decrease.setOnAction(e -> {
            fanTimeline.setRate(
                    (fanTimeline.getCurrentRate() - 1 < 0) ? 0 : fanTimeline.getCurrentRate() - 1);
            mSlider.setValue(fanTimeline.getCurrentRate());

        });

        Button reverse = new Button("Reverse");
        reverse.setOnAction(e-> fanPane.increment *= -1);
        HBox hButtons = new HBox(pause,resume,reverse);
        hButtons.setSpacing(10);
        hButtons.setAlignment(Pos.CENTER);
        hButtons.setPadding(new Insets(10, 10, 10, 10));
        BorderPane borderPane = new BorderPane(fanPane, null, null, hButtons, null);







        primaryStage.setScene(new Scene(borderPane));
        primaryStage.setTitle("Spinning fan");
        primaryStage.show();
    }

    public static void main(String[] args) {
        Application.launch(args);
    }

    private class FanPane extends Pane {

        private Circle c;
        private Arc[] blades = new Arc[4];
        private double increment = 1;




        Slider mSlider = new Slider();
        HBox scrollPane = new HBox(mSlider);


        FanPane(double radius) {
            setMinHeight(400);
            setMinWidth(400);
            c = new Circle(200,200,radius,Color.BLUE);
            c.setStroke(Color.BLACK);

            double bladeRadius = radius * 0.9;
            for (int i = 0; i < blades.length; i++) {
                blades[i] = new Arc(
                        c.getCenterX(), c.getCenterY(), // center point
                        bladeRadius, bladeRadius, // X and Y radius
                        (i * 90) + 30, 35); // start angle and length
                blades[i].setFill(Color.YELLOW);
                blades[i].setType(ArcType.ROUND);
            }

            getChildren().addAll(c);
            getChildren().addAll(blades);


        }



        private void spin() {
            for (Arc blade : blades) {
                double prevStartAngle = blade.getStartAngle();
                blade.setStartAngle(prevStartAngle + increment);
            }
        }

    }
}