[FIXED] NullPointerException after building jar

Issue

I have a JavaFX project that i develop with IntelliJ and when i run the program from there everythin works fine.

But when i run mvn clean package and try to run the jar that is built i get the following Exception:

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
        at de.application.component.main.FilterListCell.setParent(FilterListCell.java:212)
        at de.application.controller.MainController.lambda$initialize$2(MainController.java:183)
        at javafx.scene.control.skin.ListViewSkin.createCell(ListViewSkin.java:432)
        at javafx.scene.control.skin.ListViewSkin.lambda$new$9(ListViewSkin.java:207)
        at javafx.scene.control.skin.VirtualFlow.getCell(VirtualFlow.java:1672)
        at javafx.scene.control.skin.VirtualFlow.getCellLength(VirtualFlow.java:1801)
        at javafx.scene.control.skin.VirtualFlow.computeViewportOffset(VirtualFlow.java:2639)
        at javafx.scene.control.skin.VirtualFlow.layoutChildren(VirtualFlow.java:1245)
        at javafx.scene.Parent.layout(Parent.java:1204)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Parent.layout(Parent.java:1211)
        at javafx.scene.Scene.doLayoutPass(Scene.java:576)
        at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2482)
        at com.sun.javafx.tk.Toolkit.lambda$runPulse$2(Toolkit.java:412)
        at java.base/java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.tk.Toolkit.runPulse(Toolkit.java:411)
        at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:438)
        at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:519)
        at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:499)
        at com.sun.javafx.tk.quantum.QuantumToolkit.pulseFromQueue(QuantumToolkit.java:492)
        at com.sun.javafx.tk.quantum.QuantumToolkit.lambda$runToolkit$11(QuantumToolkit.java:320)
        at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
        at java.base/java.lang.Thread.run(Thread.java:834)

This is the line that fails:

public void setParent(ListView<CompositeFilter> parent) {
    this.parent = parent;
    root.prefWidthProperty().bind(parent.widthProperty().subtract(16)); // this fails
}

root is being null what I don't understand because I declare it in the controler like this

    @FXML
    public AnchorPane root;

and this is the fxml file:

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

<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane fx:id="root" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity"
            minWidth="-Infinity" prefHeight="200.0" xmlns="http://javafx.com/javafx/11.0.1"
            xmlns:fx="http://javafx.com/fxml/1"
            fx:controller="de.application.component.main.FilterListCell">
  <HBox alignment="CENTER_LEFT" AnchorPane.leftAnchor="8.0" AnchorPane.topAnchor="8.0" AnchorPane.rightAnchor="8.0">
   <!-- some content -->
  </HBox>
</AnchorPane>

I have no idea why this is the case, i checked that IntelliJ uses the same JDK as i do.

Maybe this is an issue with my pom?

Here it is:

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.7.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>
  <groupId>de.group</groupId>
  <artifactId>application</artifactId>
  <version>0.1-SNAPSHOT</version>

  <properties>
    <java.version>11</java.version>
    <javafx.version>11.0.2</javafx.version>
    <maven.compiler.plugin.version>3.8.1</maven.compiler.plugin.version>
  </properties>

  <dependencies>
    <!-- JavaFX -->
    <dependency>
      <groupId>org.openjfx</groupId>
      <artifactId>javafx-controls</artifactId>
      <version>${javafx.version}</version>
    </dependency>
    <dependency>
      <groupId>org.openjfx</groupId>
      <artifactId>javafx-fxml</artifactId>
      <version>${javafx.version}</version>
    </dependency>
    <dependency>
      <groupId>org.openjfx</groupId>
      <artifactId>javafx-graphics</artifactId>
      <version>${javafx.version}</version>
    </dependency>
    <dependency>
      <groupId>org.openjfx</groupId>
      <artifactId>javafx-base</artifactId>
      <version>${javafx.version}</version>
    </dependency>

    <dependency>
      <groupId>org.controlsfx</groupId>
      <artifactId>controlsfx</artifactId>
      <version>11.0.1</version>
    </dependency>
    <!-- Spring Boot -->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
    </dependency>

    <!-- Other -->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.module</groupId>
      <artifactId>jackson-module-parameter-names</artifactId>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.datatype</groupId>
      <artifactId>jackson-datatype-jdk8</artifactId>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.datatype</groupId>
      <artifactId>jackson-datatype-jsr310</artifactId>
    </dependency>

    <dependency>
      <groupId>net.rgielen</groupId>
      <artifactId>javafx-weaver-spring</artifactId>
      <version>1.2.0</version>
    </dependency>

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-configuration-processor</artifactId>
      <optional>true</optional>
    </dependency>

    <!-- Test -->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>${maven.compiler.plugin.version}</version>
        <configuration>
          <source>${java.version}</source>
          <target>${java.version}</target>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>

</project>

All help will be greatly appreciated.

EDIT

The code snippet from the MainController is this

lstFilter.setCellFactory(compositeFilterListView -> {
            FxControllerAndView<FilterListCell, Node> cell = fxWeaver.load(FilterListCell.class);
            if(cell.getView().isPresent()) {
                cell.getView().get().setVisible(false);
                cell.getController().setGraphic(cell.getView().get());
            }
            cell.getController().setParent(lstFilter); // setParent fails
            return cell.getController();
        });

This is just a CellFactory for the Listview lstFilter. The real problem is the discrepency between running through Intellij, where this error does not occur and running the built jar trough the command line, where this fails.

Solution

So I figured out a solution to my problem:

The prolem was that my fxml file was not found. I am still not sure why. The controller class was called FilterListView and my fxml file filterListView.fxml. Now i renamed the fxml file to FilterListView.fxml and it works.

Does anyone know why the classpath seems to be case-sensitive when running a jar and not case-sensitive when running from the IDE?

Answered By - Amir Schnell
Answer Checked By - Mary Flores (JavaFixing Volunteer)