JavaFX lineChart

Cześć,

Mam problem z Line Chart w javafx.
Dostaje jakiś dziwny wyjątek kiedy chcę dodać do lineChart dane.

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package chartslab4;

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

/**
 *
 * @author student
 */
public class ChartsLab4 extends Application {
    
    @Override
    public void start(Stage stage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));
        
        Scene scene = new Scene(root);
        
        stage.setScene(scene);
        stage.setWidth(800);
        stage.setHeight(600);
        stage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) { 
        launch(args);
    }  
}


```java
package chartslab4;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.ResourceBundle;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.chart.AreaChart;
import javafx.scene.chart.CategoryAxis;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.ScatterChart;
import javafx.scene.chart.XYChart.Data;
import javafx.scene.chart.XYChart.Series;
import javafx.scene.control.RadioButton;
import javafx.scene.control.ToggleGroup;

public class FXMLDocumentController {

    @FXML
    private ResourceBundle resources;

    @FXML
    private URL location;

    @FXML
    private AreaChart<String, Number> areaChart;

    @FXML
    private LineChart<String, Number> lineChart;

    @FXML
    private ScatterChart<String, Number> scatterChart;

    @FXML
    private RadioButton scatterChartRadioButton;

    @FXML
    private ToggleGroup chart;

    @FXML
    private RadioButton lineChartRadioButton;

    @FXML
    private RadioButton areaChartRadioButton;

    @FXML
    void radioButtonSelection(ActionEvent event) {
        this.disableAllcharts();
        if (lineChartRadioButton.isSelected()) {
            lineChart.setVisible(true);
        } else if (scatterChartRadioButton.isSelected()) {
            scatterChart.setVisible(true);
        } else if (areaChartRadioButton.isSelected()) {
            areaChart.setVisible(true);
        }
    }

    private List<Series<String, Number>> data;

    private void disableAllcharts() {
        lineChart.setVisible(false);
        scatterChart.setVisible(false);
        areaChart.setVisible(false);
    }

    @FXML
    void initialize() {
        assert scatterChart != null : "fx:id=\"scatterChart\" was not injected: check your FXML file 'FXMLDocument.fxml'.";
        assert lineChart != null : "fx:id=\"lineChart\" was not injected: check your FXML file 'FXMLDocument.fxml'.";
        assert areaChart != null : "fx:id=\"areaChart\" was not injected: check your FXML file 'FXMLDocument.fxml'.";
        assert lineChartRadioButton != null : "fx:id=\"lineChartRadioButton\" was not injected: check your FXML file 'FXMLDocument.fxml'.";
        assert chart != null : "fx:id=\"chart\" was not injected: check your FXML file 'FXMLDocument.fxml'.";
        assert scatterChartRadioButton != null : "fx:id=\"scatterChartRadioButton\" was not injected: check your FXML file 'FXMLDocument.fxml'.";
        assert areaChartRadioButton != null : "fx:id=\"areaChartRadioButton\" was not injected: check your FXML file 'FXMLDocument.fxml'.";
        try {
            this.initcharts();
        } catch (IOException ex) {
            Logger.getLogger(FXMLDocumentController.class.getName()).log(Level.SEVERE, null, ex);
            System.exit(-1);
        }
        
        /*final CategoryAxis xAxis = new CategoryAxis();
        final NumberAxis yAxis = new NumberAxis();
         xAxis.setLabel("Month");
        lineChart = new LineChart<String,Number>(xAxis,yAxis);*/

        this.disableAllcharts();
        lineChart.setVisible(true);

        areaChart.setTitle("Area chart");
        lineChart.setTitle("Line chart");
        scatterChart.setTitle("Scatter chart");

        lineChart.setCreateSymbols(false);
        
        areaChart.getData().addAll(data);
        lineChart.getData().addAll(data);
        scatterChart.getData().addAll(data);
    }

    private void initcharts() throws FileNotFoundException, IOException {
        String[] files = {this.getClass().getResource("file1.txt").getPath(),
            this.getClass().getResource("file2.txt").getPath(),
            this.getClass().getResource("file3.txt").getPath()};

        data = new ArrayList<>();

        for (String f : files) {
            System.out.println(f);
            BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(f)));
            Series<String, Number> seria = new Series<>();
            ObservableList<Data<String, Number>> list = FXCollections.observableArrayList();
            String line;

            int y = 1;
            while ((line = br.readLine()) != null) {
                list.add(new Data<>(Integer.toString(y++), line.length()));
            }
            
            seria.setName(f);
            seria.setData(list);
            data.add(seria);
        }
    }

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

<?import javafx.geometry.Insets?>
<?import javafx.scene.chart.AreaChart?>
<?import javafx.scene.chart.CategoryAxis?>
<?import javafx.scene.chart.LineChart?>
<?import javafx.scene.chart.NumberAxis?>
<?import javafx.scene.chart.ScatterChart?>
<?import javafx.scene.control.RadioButton?>
<?import javafx.scene.control.ToggleGroup?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.StackPane?>
<?import javafx.scene.layout.VBox?>

<AnchorPane id="AnchorPane" xmlns="http://javafx.com/javafx/8.0.111" xmlns:fx="http://javafx.com/fxml/1" fx:controller="chartslab4.FXMLDocumentController">
   <children>
      <VBox layoutX="110.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
         <children>
            <StackPane>
               <children>
                  <ScatterChart fx:id="scatterChart">
                    <xAxis>
                      <CategoryAxis side="BOTTOM" />
                    </xAxis>
                    <yAxis>
                      <NumberAxis side="LEFT" />
                    </yAxis>
                  </ScatterChart>
                  <LineChart fx:id="lineChart">
                    <xAxis>
                      <CategoryAxis side="BOTTOM" />
                    </xAxis>
                    <yAxis>
                      <NumberAxis side="LEFT" />
                    </yAxis>
                  </LineChart>
                  <AreaChart fx:id="areaChart">
                    <xAxis>
                      <CategoryAxis side="BOTTOM" />
                    </xAxis>
                    <yAxis>
                      <NumberAxis side="LEFT" />
                    </yAxis>
                  </AreaChart>
               </children>
               <VBox.margin>
                  <Insets bottom="15.0" left="15.0" right="15.0" top="15.0" />
               </VBox.margin>
            </StackPane>
            <HBox spacing="15.0">
               <children>
                  <RadioButton fx:id="lineChartRadioButton" mnemonicParsing="false" onAction="#radioButtonSelection" selected="true" text="Line chart">
                     <toggleGroup>
                        <ToggleGroup fx:id="chart" />
                     </toggleGroup>
                  </RadioButton>
                  <RadioButton fx:id="scatterChartRadioButton" mnemonicParsing="false" onAction="#radioButtonSelection" text="Scatter Chart" toggleGroup="$chart" />
                  <RadioButton fx:id="areaChartRadioButton" mnemonicParsing="false" onAction="#radioButtonSelection" text="Area Chart" toggleGroup="$chart" />
               </children>
               <VBox.margin>
                  <Insets bottom="15.0" left="15.0" right="15.0" top="15.0" />
               </VBox.margin>
            </HBox>
         </children>
      </VBox>
   </children>
</AnchorPane>

Exception in Application start method
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
        at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
        at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$155(LauncherImpl.java:182)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassCastException: javafx.scene.shape.Path cannot be cast to javafx.scene.Group
        at javafx.scene.chart.AreaChart.layoutPlotChildren(AreaChart.java:444)
        at javafx.scene.chart.XYChart.layoutChartChildren(XYChart.java:731)
        at javafx.scene.chart.Chart$1.layoutChildren(Chart.java:94)
        at javafx.scene.Parent.layout(Parent.java:1087)
        at javafx.scene.Parent.layout(Parent.java:1093)
        at javafx.scene.Parent.layout(Parent.java:1093)
        at javafx.scene.Parent.layout(Parent.java:1093)
        at javafx.scene.Parent.layout(Parent.java:1093)
        at javafx.scene.Scene.doLayoutPass(Scene.java:552)
        at javafx.scene.Scene.preferredSize(Scene.java:1646)
        at javafx.scene.Scene.impl_preferredSize(Scene.java:1720)
        at javafx.stage.Window$9.invalidated(Window.java:846)
        at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:109)
        at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:144)
        at javafx.stage.Window.setShowing(Window.java:922)
        at javafx.stage.Window.show(Window.java:937)
        at javafx.stage.Stage.show(Stage.java:259)
        at chartslab4.ChartsLab4.start(ChartsLab4.java:29)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
        at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
        at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
        at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
        ... 1 more
Exception running application chartslab4.ChartsLab4

Błąd jest kiedy zostaje wywoływana linijka: lineChart.getData().addAll(data); w drugim pliku

Proszę o pomoc w rozwiązaniu tego problemu.
Z góry dziękuje :)