Develop Reference

FXML: no controller specified, while controller is specified in controller

I am trying to use multiple fxml files in an application I am making, and in doing some research, I found that using Custom Controllers for the fxml files is the best approach towards doing this type of application.
I followed an Oracle Docs tutorial on "Mastering FXML" and set the root and controller as "this" in the CustomController.java file.
The problem arises when intellij discovers there is no controller specified in the fxml file for the onAction handler, while I am specifying the controller programmatically.
tester.java
package task01;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class tester extends Application
{
#Override
public void start(Stage stage) throws Exception
{
CustomController customController = new CustomController();
customController.getStylesheets().add("/task01/stylize.css");
stage.setScene(new Scene(customController,1920,1080));
stage.setTitle("Seneca ATM Program");
stage.setWidth(1920);
stage.setHeight(1080);
stage.show();
}
public static void main(String[] args)
{
Application.launch(args);
}
}
CustomContoller.java
package task01;
import javafx.event.ActionEvent;
import javafx.scene.control.Button;
import javafx.scene.layout.GridPane;
import javafx.fxml.*;
import javafx.scene.layout.Pane;
import java.io.IOException;
public class CustomController extends GridPane
{
#FXML
private Pane viewableContent;
#FXML
private Button vigilanteButton;
public CustomController()
{
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("root.fxml"));
fxmlLoader.setRoot(this);
fxmlLoader.setController(this);
try
{
fxmlLoader.load();
} catch (IOException exception)
{
throw new RuntimeException(exception);
}
}
#FXML
private void vigilanteAction(ActionEvent actionEvent)
{
System.out.println("Hello, World");
}
}
root.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.GridPane?>
<?import task01.MainMenuController?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.Pane?>
<fx:root type="javafx.scene.layout.GridPane" xmlns:fx="http://javafx.com/fxml" alignment="CENTER">
<ImageView fitWidth="229.67" fitHeight="149.67" GridPane.columnIndex="0" GridPane.rowIndex="0" GridPane.halignment="CENTER">
<Image url="/task01/logo.png"/>
</ImageView>
<Pane fx:id="viewableContent" GridPane.columnIndex="0" GridPane.rowIndex="1" GridPane.halignment="CENTER">
<MainMenuController/>
</Pane>
<Button fx:id="vigilanteButton">Vigilante</Button>
</fx:root>
MainMenuController.java
package task01;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.control.Button;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import java.io.IOException;
public class MainMenuController extends GridPane
{
private CustomController customController = new CustomController();
public MainMenuController()
{
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("mainmenu.fxml"));
fxmlLoader.setRoot(this);
fxmlLoader.setController(this);
try
{
fxmlLoader.load();
} catch (IOException exception)
{
throw new RuntimeException(exception);
}
}
#FXML
private VBox buttonSet;
#FXML
private HBox buttonSetOne;
#FXML
private HBox buttonSetTwo;
#FXML
private Button changePinButton;
#FXML
private Button accountInquiryButton;
#FXML
private Button withdrawMoneyButton;
#FXML
private Button depositMoneyButton;
#FXML
private Button balanceInquiryButton;
#FXML
private Button createAccountButton;
#FXML
private GridPane gridpane;
#FXML
public void createAccountAction(ActionEvent actionEvent)
{
}
}
mainmenu.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.geometry.Insets?>
<GridPane fx:id="gridpane" alignment="CENTER" vgap="50" hgap="50" xmlns:fx="http://javafx.com/fxml">
<padding><Insets top="10" bottom="10" left="10" right="10"/></padding>
<VBox fx:id="buttonSet" spacing="25" GridPane.columnIndex="0" GridPane.rowIndex="1">
<HBox fx:id="buttonSetOne" spacing="25">
<Button styleClass="menuButton" fx:id="createAccountButton" onAction="#createAccountAction">Create account</Button>
<Button styleClass="menuButton" fx:id="changePinButton">Change PIN</Button>
<Button styleClass="menuButton" fx:id="accountInquiryButton">Account Inquiry</Button>
</HBox>
<HBox fx:id="buttonSetTwo" spacing="25">
<Button styleClass="menuButton" fx:id="withdrawMoneyButton">Withdraw Money</Button>
<Button styleClass="menuButton" fx:id="depositMoneyButton">Deposit Money</Button>
<Button styleClass="menuButton" fx:id="balanceInquiryButton">Balance Inquiry</Button>
</HBox>
</VBox>
</GridPane>

Here's the problem, you can bind a FXML file to a Controller from the controller, but when you do this the IDE doesn't know it until it's up and running. That's why the IDE causes you troubles. If you want to set the onAction handler you'll have to do it from the controller. You have to create a method like this and add the onAction listener to the button:
#FXML
public void initialize() {
createAccountButton.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
// TODO Auto-generated method stub
createAccountAction(event);
}
});
}

Divide and conquer: break complex problems to smaller ones. Start with a simple setup like the following.
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;
public class tester extends Application
{
#Override
public void start(Stage stage) throws Exception
{
CustomController customController = new CustomController();
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("root.fxml"));
fxmlLoader.setController(customController);
Parent root = (Parent)fxmlLoader.load();
stage.setScene(new Scene(root,1920,1080));
stage.setTitle("Seneca ATM Program");
stage.show();
}
public static void main(String[] args)
{
Application.launch(args);
}
}
//controller should be just that. It is not a pane
class CustomController /* extends GridPane */
{
#FXML
private Pane viewableContent;
#FXML
private Button vigilanteButton;
#FXML
private void vigilanteAction(ActionEvent actionEvent)
{
System.out.println("Hello, World");
}
}
root.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.GridPane?>
<!-- ?import task01.MainMenuController?-->
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.Pane?>
<GridPane xmlns:fx="http://javafx.com/fxml" alignment="CENTER">
<ImageView fitWidth="229.67" fitHeight="149.67" GridPane.columnIndex="0" GridPane.rowIndex="0"
GridPane.halignment="CENTER">
<Image url="task01/logo.png"/> <!-- todo: set correct path -->
</ImageView>
<Button fx:id="vigilanteButton" onAction="#vigilanteAction">Vigilante</Button>
</GridPane>
I hope this helps you to structure your application.

There's no way for the IDE to know about you setting the controller yourself somewhere in your java code. Autocompletion features and the like are off for this reason. The fact that the IDE shows these kind of "issues" is unfortunate in this case, but they could indicate an issue that can only be recognized at runtime.
In your case assuming you don't have any typos in your fxml, it's safe to ignore these warnings.
You could of course simply add the fx:controller attribute temporarily while editing the fxml and remove it when you're done.
Another way of dealing with this issue would be specifying the fx:controller attribute in the fxml and setting the controllerFactory property instead of the controller property for the loader. I don't really like this approach though:
<GridPane fx:id="gridpane" alignment="CENTER" vgap="50" hgap="50" xmlns:fx="http://javafx.com/fxml" fx:controller="task01.MainMenuController">
...
public MainMenuController() {
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("mainmenu.fxml"));
fxmlLoader.setRoot(this);
fxmlLoader.setControllerFactory(clazz -> {
if (!clazz.isInstance(this)) {
throw new IllegalArgumentException(String.format("class of controller (%s) not assignable to class specified in fxml (%s)", this.getClass().getName(), clazz.getName()));
}
return this;
});
try {
fxmlLoader.load();
} catch (IOException exception) {
throw new RuntimeException(exception);
}
}
If you don't want to check assignment compatibility between the controller type specified in the fxml and the type of the controller you specify, the controllerFactory could be simplified to clazz -> this.
If you want to use this approach for multiple classes I strongly recommend creating a class for the controller factory to avoid repetitions, assuming you want to do the check...

Javafx NPE when updating Label via Hotkey

For education purposes I am trying to add hotkeys to my javafx application. Using my sample code, I am unable to access my label via hotkey. Using a button I can call the very same method updating my label succesfully.
The View:
<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane id="AnchorPane" prefHeight="62.0" prefWidth="91.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="fx.probleme.SampleViewController">
<children>
<Label id="label" fx:id="label" layoutX="14.0" layoutY="45.0" text="Label" />
<Button layoutX="20.0" layoutY="14.0" mnemonicParsing="false" onAction="#updateText" text="Button" />
</children>
</AnchorPane>
And the controller:
package fx.probleme;
import javafx.application.Application;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.stage.Stage;
public class SampleViewController extends Application {
#FXML
Label label;
#FXML
void updateText() {
label.setText(label.getText() + "+");
}
#Override
public void start(Stage stage) throws Exception {
Parent parent = FXMLLoader.load(this.getClass().getResource("SampleView.fxml"));
Scene scene = new Scene(parent);
scene.setOnKeyPressed((final KeyEvent keyEvent) -> {
if (keyEvent.getCode() == KeyCode.NUMPAD0) {
updateText();
}
});
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}

You get NullPointerException, because at that stage the Label is not initialized, the initialization is done in the initialize.
First of all you have mixed your main class with your controller class, you may want to separate them, setting a controller that implements Initializable, after that in the initialize method you can call any method of the components because in it all of the components annotated by #FXML are initialized. In your case, in start method is not yet initialized. Also you may don't want to use the scene's method, instead of you can add events, actions to your content pane, in your case to the AnchorPane.
I would suggest to separate the controller class from your main class, and implement Initializable. This helps you to have a better vision over your application, you cans see where exactly your components are initialized, were are you sure about using their methods, without NPE.
If you don't want to do it in a separate class(which is recommended) you can add an fx:id for AnchorPane in the .fxml file, then you can add the method to onKeyPressed like you did for the Button.

javafx: how to handle items(textfields, labels, etc)?

i used scene builder to generate a layout, after exporting the fxml i imported into TextPad, the layout was sucessefuly imported however i cant handle the items by the id(if thats how it works). my question is how do handle the items that i added.
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.fxml.FXMLLoader;
public class test2fx extends Application{
public static void main(String[] args){
Application.launch(args);
}
public void init(){
}
#Override
public void start(Stage stage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("fxlayout.fxml"));
Scene scene = new Scene(root, 300, 275);
stage.setTitle("FXML Welcome");
stage.setScene(scene);
stage.show();
}
public void stop(){
System.exit(0);
}
fxml file content:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.Pane?>
<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="284.0" prefWidth="314.0" xmlns="http://javafx.com/javafx/8.0.60" xmlns:fx="http://javafx.com/fxml/1">
<children>
<Button layoutX="31.0" layoutY="252.0" mnemonicParsing="false" prefHeight="25.0" prefWidth="50.0" text="Jogar" />
<Button layoutX="124.0" layoutY="252.0" mnemonicParsing="false" prefHeight="25.0" prefWidth="50.0" text="Novo" />
<Button layoutX="219.0" layoutY="252.0" mnemonicParsing="false" prefHeight="25.0" prefWidth="50.0" text="Sair" />
<TextField id="tf1" disable="true" layoutX="150.0" layoutY="60.0" />
<TextField id="tf1" disable="true" layoutX="150.0" layoutY="100.0" />
<TextField id="tf3" layoutX="150.0" layoutY="140.0" />
<TextField id="tf4" disable="true" layoutX="150.0" layoutY="180.0" />
<Label id="lb1" layoutX="38.0" layoutY="60.0" prefHeight="22.0" prefWidth="59.0" text="Inicio" />
<Label id="lb2" layoutX="38.0" layoutY="100.0" prefHeight="22.0" prefWidth="59.0" text="Fim" />
<Label id="lb3" layoutX="38.0" layoutY="139.0" prefHeight="22.0" prefWidth="59.0" text="Palpite" />
<Label id="lb4" layoutX="38.0" layoutY="180.0" prefHeight="22.0" prefWidth="59.0" text="Inicio" />
</children>
</Pane>

As #James_D said you most likely want:
A reference to the element in your FXMl you wish to access.
A controller class for your FXML.
Example:
/*
* Dean2191 Stackoverflow example
*/
package javafxapplication6;
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.TextField;
/**
*
* #author dean2191
*/
public class FXMLDocumentController implements Initializable {
#FXML
private Label label;
#FXML
private TextField tf1; // value will be injected by the FXMLLoader
#FXML
private void handleButtonAction(ActionEvent event) {
System.out.println("You clicked me!");
label.setText("Hello World!");
}
#Override
public void initialize(URL url, ResourceBundle rb) {
// TODO
}
}
Check the oracle examples here and also note that the netbeans IDE generates a default controller class as shown above however when a new element is added in scene builder you should add each #FXML annotation to the variable you wish to access and scene builder/netbeans have synchronization features to view which elements are referenced from your code.
Synchronizing With the Controller Source Code The NetBeans IDE's Make
Controller feature allows you to synchronize the modifications you
make in the FXML file that is currently opened in Scene Builder and
the controller source code opened in NetBeans IDE. To illustrate this
feature, do the following:
In Scene Builder, drag a Button control from the Library panel to the
Control panel. In the Code panel, assign a new value for the new
button's fx:id field and a new method name for the onAction method.
Select File in the main menu and then Save. In NetBeans IDE 7.4 or
later, right click the project node for the FXML file that you just
edited and select Edit from the contextual menu. From the main menu,
select Source and then Make Controller. The #FXML private variable and
the new onAction method for the button you just added in Scene Builder
are created in the controller source file. Use the Make Controller
command if you delete an element in the Control panel or update an
fx:id value or a method name in Scene Builder.
Source
Also note you should check in your FXMl for this line:
fx:controller="yourNamespace.fxlayout"
As your controller class must be specified somewhere in the FXML. Your controller will then be called something like fxlayout.java in your example code. This can be set/modified using scene builder too:

Java TextArea setText() and appendText() returning Null Pointer Exception [duplicate]

This question already has an answer here:
javafx 8 compatibility issues - FXML static fields
(1 answer)
Closed 8 years ago.
I am using JavaFX 8 and FXML in this project and trying to update my text area with the results from other classes within the program.
The Text Area is defined in the FXML document as such:
<TextArea fx:id="feedBack" editable="false" focusTraversable="false"
layoutX="203.0" layoutY="32.0" prefHeight="205.0" prefWidth="308.0"
wrapText="true"/>
It is called in the controller here, note that originally it was a "private" item but to make it work with the classes I made it public:
#FXML
public static TextArea feedBack;
EDIT: It is worth noting that when the TextArea is identified as "private" I have no issue getting the set/append text method to work but this does not allow me to use the text area in other classes, which is what I need to do.
However now when I try to do either appendText() or setText(), such as follows:
feedBack.setText("Connection Made");
I am given a null point exception. Why is this? I have made this work in JavaFX 7 with FXML by doing the same thing and it works fine. What am I missing to make this work?
EDIT, test/proof of brokenness with complete tiny program.
I did not make another class for this one as the textarea won't work in the control anyway.
FXML:
<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane id="AnchorPane" prefHeight="200" prefWidth="320" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="textareatester.FXMLDocumentController">
<children>
<Label fx:id="label" layoutX="126" layoutY="120" minHeight="16" minWidth="69" />
<TextArea fx:id="feedback" layoutX="61.0" prefHeight="200.0" prefWidth="200.0" wrapText="true" />
<Button fx:id="dostuff" layoutX="261.0" layoutY="62.0" mnemonicParsing="false" onAction="#handleButtonAction" text="Button" />
</children>
</AnchorPane>
Main Method:
package textareatester;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class TextAreaTester 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);
}
}
Controller Class:
package textareatester;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
public class FXMLDocumentController implements Initializable {
#FXML
private Label label;
#FXML
public static TextArea feedback;
#FXML
private Button dostuff;
#FXML
private void handleButtonAction(ActionEvent event) {
System.out.println("You clicked me!");
feedback.setText("Hello World!"); ///<-- this is what gives me the NPE
}
#Override
public void initialize(URL url, ResourceBundle rb) {
// not touching anything
}
}
Solution for those who are curious:
I ended up simply returning my results strings from my methods and then appending them to the TextArea.

The problem is the static at the definition of the TextArea. Since static attributes are bound to the class and not the object, variable feedback is never initiated and thus is null when accessed in the EventHandler.

JavaFX showing view make in scene builder with controller

I have this controller:
package cz.vutbr.feec.bmds.cv2;
import java.awt.Button;
import java.awt.TextField;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Slider;
public class TestGuiController {
private int buttonPressed = 0;
#FXML
private Button tlacitko;
#FXML
private TextField textovePole;
#FXML
private Slider slider;
public void buttonPressed(ActionEvent e) {
buttonPressed++;
textovePole.setText(Integer.toString(buttonPressed));
}
}
this fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.BorderPane?>
<AnchorPane prefHeight="200.0" prefWidth="200.0" xmlns:fx="http://javafx.com/fxml" fx:controller="cz.vutbr.feec.bmds.cv2.TestGuiController">
<children>
<Button fx:id="tlacitko" layoutX="30.0" layoutY="40.0" mnemonicParsing="false" onTouchPressed="#buttonPressed" text="Button" />
<Slider fx:id="slider" layoutX="157.0" layoutY="17.0" orientation="VERTICAL" />
<TextField fx:id="textovePole" layoutX="14.0" layoutY="89.0" prefWidth="134.0" />
</children>
</AnchorPane>
and this is my main class:
package cz.vutbr.feec.bmds.cv2;
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("TestGui.fxml"));
primaryStage.setTitle("Titulek");
primaryStage.setScene(new Scene(root,300,275));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
When I run this through ant I get message box with error (exception during running application). I tried simple fxml without controller and it works so I am guesing I do something wrong with controller. What I must change to have it working?

I must answer my own question. Problem was in TestGuiController where I used java.awt.Button and java.awt.TextField instead of javafx.scene.control.Button and javafx.scene.control.TextField.

I'm not 100% sure but try:
in FXML: Button: onAction instead of onTouchPressed
Please provide the exact Exception message.