JavaFX and Scene Builder - Drawing Power and Exponential Function

Controller.java

package sample;

import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.RadioButton;
import javafx.scene.control.Slider;
import javafx.scene.layout.Pane;
import javafx.scene.shape.Circle;
import javafx.scene.text.Text;

import java.net.URL;
import java.util.ResourceBundle;

public class Controller implements Initializable {

    @FXML
    private Pane coordinateSystem;
    @FXML
    private Slider aSlider;
    @FXML
    private Slider bSlider;
    @FXML
    private Text functionText;
    @FXML
    private RadioButton powerFunction;
    @FXML
    private RadioButton exponentialFunction;

    private int paneWidth = 300;

    Function function;

    @Override
    public void initialize(URL url, ResourceBundle resourceBundle) {
        setupSlider(aSlider);
        setupSlider(bSlider);
    }

    private void setupSlider(Slider Slider) {
        Slider.valueProperty().addListener(new ChangeListener<Number>() {
            @Override
            public void changed(ObservableValue<? extends Number> observableValue, Number number, Number t1) {
                if(powerFunction.isSelected()){
                    function = new PowerFunction(aSlider.getValue(),bSlider.getValue());
                } else if(exponentialFunction.isSelected()){
                    function = new ExponentialFunction(aSlider.getValue(),bSlider.getValue());
                }
                coordinateSystem.getChildren().clear();
                drawFunction();
            }
        });
    }

    public void drawFunction(){
        functionText.setText(function.toString());
        for (double i = 0; i < 200; i = i + 0.5) {
            coordinateSystem.getChildren().add(drawPoint(i,function.getY(i)));
        }
    }

    public Circle drawPoint(double x, double y){
        return new Circle(x,-(y-paneWidth),1);
    }
}

ExponentialFunction.java

package sample;

public class ExponentialFunction extends Function{

    public ExponentialFunction(double a, double b) {
        super(a, b);
    }

    @Override
    public double getY(double x) {
        return getB() * Math.pow(getA(),x);
    }

    @Override
    public String toString() {
        return "f(x)=" + df.format(getB()) + "*" + df.format(getA()) + "^x";
    }
}

Function.java

package sample;

import java.text.DecimalFormat;

public abstract class Function {

    private double a;
    private double b;

    DecimalFormat df = new DecimalFormat("#.00");

    public Function(double a, double b) {
        this.a = a;
        this.b = b;
    }

    abstract public double getY(double x);

    public double getA() {
        return a;
    }

    public double getB() {
        return b;
    }
}

Main.java

package sample;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }


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

PowerFunction.java

package sample;

public class PowerFunction extends Function {

    public PowerFunction(double a, double b) {
        super(a, b);
    }

    @Override
    public double getY(double x){
        return getB() * Math.pow(x,getA());
    }

    @Override
    public String toString() {
        return "f(x)=" + df.format(getB()) + "*x^" + df.format(getA());
    }
}

sample.fxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.RadioButton?>
<?import javafx.scene.control.Slider?>
<?import javafx.scene.control.ToggleGroup?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.Pane?>
<?import javafx.scene.text.Font?>
<?import javafx.scene.text.Text?>

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/15.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
   <children>
      <Pane fx:id="coordinateSystem" layoutX="251.0" layoutY="50.0" prefHeight="300.0" prefWidth="300.0" />
      <Slider fx:id="aSlider" layoutX="31.0" layoutY="155.0" majorTickUnit="0.5" max="3.0" minorTickCount="1" showTickLabels="true" showTickMarks="true" value="1.1" />
      <Slider fx:id="bSlider" layoutX="31.0" layoutY="220.0" showTickLabels="true" showTickMarks="true" value="1.0" />
      <Text fx:id="functionText" layoutX="31.0" layoutY="297.0" strokeType="OUTSIDE" strokeWidth="0.0" text="Pick a function">
         <font>
            <Font size="20.0" />
         </font>
      </Text>
      <RadioButton fx:id="powerFunction" layoutX="38.0" layoutY="42.0" mnemonicParsing="false" text="f(x)=b*x^a">
         <toggleGroup>
            <ToggleGroup fx:id="functions" />
         </toggleGroup>
      </RadioButton>
      <RadioButton fx:id="exponentialFunction" layoutX="38.0" layoutY="61.0" mnemonicParsing="false" text="f(x)=b*a^x" toggleGroup="$functions" />
      <Text layoutX="190.0" layoutY="27.0" strokeType="OUTSIDE" strokeWidth="0.0" text="Power Function and Exponential Function" />
   </children>
</AnchorPane>