JavaFX LineChart Error: "Instances of javafx.scene.chart.LineChart cannot be created by FXML loader. (Java 11, JavaFX 17)

Question

I am in the process of moving my JavaFX project from Java 8 to Java 11, JavaFX 17 for the past week or so. I also moved from Scenebuilder 8.5 to Scenebuilder JavaFX Version: 20.0.1. All in all it has been reasonably smooth, however I am facing a confusing error that I cannot seem to solve.

Instances of `javafx.scene.chart.LineChart` cannot be created by FXML loader.

When I changed the Java version of my project to Java 11, and imported the JavaFX 17 library to my project, The LineChart I am using in my project began throwing an error I had never seen before in the FXML Document file. It is a 330 line file so I will only include the relevant parts:

<?import javafx.scene.chart.CategoryAxis?>
<?import javafx.scene.chart.LineChart?>
<?import javafx.scene.chart.NumberAxis?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.ChoiceBox?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.effect.DropShadow?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.Pane?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.shape.Line?>


<LineChart fx:id="chartDashboardLineChart" layoutX="5.0" layoutY="10.0" prefHeight="233.0" prefWidth="870.0" title="Monthly Sales">
   <xAxis>
     <CategoryAxis side="BOTTOM" fx:id="x" />
   </xAxis>
   <yAxis>
     <NumberAxis fx:id="y" side="LEFT" />
   </yAxis>
</LineChart>

The error is displayed under the line where the LineChart chartDashboardLineChart is declared. There are also two new errors which read: Class javafx.scene.chart.LineChart does not support property xAxis (and the same for yAxis). These two errors seem less worrying to me than the FXML Loader error above. I will also include the relevant lines of code from my project, although I believe it is more likely that the error lies within the FXML Document. Here is the Java Code (this is split across 2 different classes: Class: LineCharts.java

And another class, this one too large to post in its entirety called DashboardController.java, Here are the relevant parts of the DashboardController class:

@FXML
private LineChart<?, ?> chartDashboardLineChart;
@FXML
private CategoryAxis x;
@FXML
private NumberAxis y;
LineCharts LC = new LineCharts();

//later on in the initialize area of the code

//Call the initializeLineChart method and pass the line chart as an argument
LC.generateDashboardLineChart(chartDashboardLineChart);

I have tried numerous things to try and fix this issue, but with no success. It seems it is a rare issue to have as there is little to no information that I could find online.

I appreciate any bit of help or any theories as to what is causing my issue, and how to solve it. Thank you!

Answer 1

I can't replicate this either by running the app or in SceneBuilder.

Verify that the following code works in your environment.

Test Environment

Execution Environment:

OS X 13.4.1, JavaFX 20.0.2, OpenJDK 19.0.2

SceneBuilder Version (from the About screen):

Product Version
JavaFX Scene Builder 19.0.0

Build Information
Version 19.0.0
Date: 2022-10-07 07:42:50
JavaFX Version: 19
Java Version: 17, OpenJDK Runtime Environment

Test Application

line-chart.fxml

<?import javafx.scene.chart.CategoryAxis?>
<?import javafx.scene.chart.LineChart?>
<?import javafx.scene.chart.NumberAxis?>

<LineChart fx:controller="com.test.demo.chart.ChartController"
           xmlns="http://javafx.com/javafx" 
           xmlns:fx="http://javafx.com/fxml" 
           fx:id="chartDashboardLineChart" 
           layoutX="5.0" layoutY="10.0" 
           prefHeight="233.0" prefWidth="870.0" 
           title="Monthly Sales">
    <xAxis>
        <CategoryAxis side="BOTTOM" fx:id="x" />
    </xAxis>
    <yAxis>
        <NumberAxis fx:id="y" side="LEFT" />
    </yAxis>
</LineChart>

ChartController.java

package com.test.demo.chart;

import javafx.scene.chart.CategoryAxis;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;

public class ChartController {
    public LineChart<String, Double> chartDashboardLineChart;
    public CategoryAxis x;
    public NumberAxis y;
}

LineChartApp.java

package com.test.demo.chart;

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

public class LineChartApp extends Application {
    @Override
    public void start(Stage stage) throws Exception {
        FXMLLoader loader = new FXMLLoader(
                LineChartApp.class.getResource(
                        "line-chart.fxml"
                )
        );

        stage.setScene(
                new Scene(
                        loader.load()
                )
        );
        stage.show();
    }

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

Output

Answer 2

I can reproduce this finding using MacOS 12.6, JDK 17.0.8, SceneBuilder 19, this Status Application or this Test Application, and NetBeans 18 with the JavaFX 2 v1.37 plugin mentioned here and here. As the plugin is outmoded, deactivating it is a simple workaround. Doing so eliminates the (spurious) error and warnings.

With reference to line-chart.fxml cite above:

 5: Instances of `javafx.scene.chart.LineChart` cannot be created by FXML loader.
12: Class `javafx.scene.chart.LineChart` does not support property `xAxis`.
15: Class `javafx.scene.chart.LineChart` does not support property `yAxis`.

Answer 3

This is a very strange error; while the error still shows on netbeans (13) in the FXML Document, it seems that when I run the project the line chart works regardless. Here is a screenshot showing the errors on netbeans:

Here is an image showing that it runs and displays the line chart regardless:!

Thanks to everyone who posted a suggestion, I very much appreciate it. I still do not understand why errors are being displayed in the FXML Document, but ultimately it does not seem to be affecting my project.