javafx.fxml.LoadException: Error resolving onSelectionChanged (tab) - javafx-2

Question

I'm experimenting FMXL with NetBeans and Scene Builder, on a Ubuntu 14.04 system.
I have a very simple App with one form, in which there is a TabPane, and this one with 2 Tabs. There is no functionality besides the default tabs selection, one at a time.
When I set a method to act on a tab selection, on Scene Builder, responding to an onSelectionChanged event, and having a method on the controller related to the fxml file, an exception is raised.
Without the above code, everything works fine (that is, compiles and runs).
The error is pointed to the XML script's attribute of the tab being defined there.
This problem is occurring with NB8.1 + SC8.1.1 + JDK1.7, and has also happened with JDK1.8; also with NB8.0.2 + SC2.2.
Is this an error of mine or a bug somewhere in the tools?
Thanks in advance.
The error message:
Executing /home/pvc/projects/java-tests/JavaFX/JavaFXApplication12/dist/run1743546166/JavaFXApplication12.jar using platform /usr/jdk1.7.0_80/bin/java
Exception in thread "main" java.lang.NoClassDefFoundError: javafx/application/Application
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
Caused by: java.lang.ClassNotFoundException: javafx.application.Application
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 13 more
Java Result: 1
The code:
package javafxapplication12;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
/**
*
* #author pvc
*/
public class JavaFXApplication12 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.show();
}
/**
* #param args the command line arguments
*/
public static void main(String[] args)
{
launch(args);
}
}
package javafxapplication12;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.control.Tab;
/**
*
* #author pvc
*/
public class FXMLDocumentController implements Initializable
{
#FXML
private Tab tab1Id;
#FXML
void handleOnTabSelected(ActionEvent event) {
System.out.println("tab1 selected");
}
#Override
public void initialize(URL url, ResourceBundle rb)
{
// TODO
}
}
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Tab?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane id="AnchorPane" prefHeight="200" prefWidth="320" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8.0.65" fx:controller="javafxapplication12.FXMLDocumentController">
<children>
<TabPane layoutX="-15.0" layoutY="-55.0" prefHeight="200.0" prefWidth="320.0" tabClosingPolicy="UNAVAILABLE" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
<tabs>
<Tab fx:id="tab1Id" closable="false" onSelectionChanged="#handleOnTab1Selected" text="tab1">
<content>
<AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0" />
</content>
</Tab>
<Tab text="Untitled Tab 2">
<content>
<AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0" />
</content>
</Tab>
</tabs>
</TabPane>
</children>
</AnchorPane>

Answer 1

You have a typo, having a 1v in the clauseonSelectionChanged="#handleOnTab1Selected"which does not match the declarationvoid handleOnTabSelected(ActionEvent event)`
However, the stack trace indicates that your project is not properly setup, and that the javafx.application.Application class cannot be resolved from the runtime.
I got my selves in trouble using the onSelectionChanged clause in the FXML, because these selection changed events are fired already before the initialize method of the controller has completed, and hence your local #FXML member variables have not been populated yet for use in the handler code.
That is a nuisance.
So I refrain from using event handler clauses in the FXML and in stead define appropriate listeners in the initialize method of the controller.