Develop Reference

JavaFX custom control use method

I made a custom control CustomControl in JavaFX.
The CustomControl is basically just a button and a text field. It is made of a CustomControl.fxml and a controller CustomControl.java.
I also have a view TestView.fxml which includes the CustomControl with a controller TestController.java. The TestView.fxml has a button. When that button is pressed it calls the method 'OnButtonPress' from the TestController.java. Now in that method I would like to call the method setText from the controller CustomControl.java.
Now I'm facing two problems.
First: I'm getting the exception 'Root hasn't been set. Use method setRoot() before load.'
Second: I don't know how to call the method setText from my custom control.
Here's the code:
TestView.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane fx:controller="controller.TestController" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/19" xmlns:fx="http://javafx.com/fxml/1">
<children>
<fx:include source="../custom_control.fxml" fx:id="custom_control"/>
<Button onAction="#OnButtonPress" fx:id="button" layoutX="148.0" layoutY="117.0" mnemonicParsing="false" text="Button" />
</children>
</AnchorPane>
TestController.java:
package controller;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.layout.VBox;
public class TestController {
#FXML
private Button button;
#FXML
private VBox custom_control;
public TestController() {
}
#FXML
private void OnButtonPress() {
// that is the method I would like to call
custom_control.setText("This is the new text");
}
}
CustomControl.java:
import java.io.IOException;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.control.TextField;
import javafx.scene.layout.VBox;
public class CustomControl extends VBox {
#FXML private TextField textField;
public CustomControl() {
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("custom_control.fxml"));
fxmlLoader.setRoot(this);
fxmlLoader.setController(this);
try {
fxmlLoader.load();
} catch (IOException exception) {
throw new RuntimeException(exception);
}
}
public void setText(String text){
textField.textProperty().set(text);
}
#FXML
protected void doSomething() {
textField.textProperty().set("The button was clicked");
}
}
CustomControl.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<fx:root type="javafx.scene.layout.VBox" xmlns:fx="http://javafx.com/fxml">
<TextField fx:id="textField"/>
<Button text="Click Me" onAction="#doSomething"/>
</fx:root>

Okey so I figured out why I didn't work so I though I'd share what problems I had.
the name's of the packages have to start with a lower case letter not upper case
The names of the Classes as well as the views (FXML files) have to start with a upper case letter.
instead of <fx:include> you should use the actual tag of the control (in my case <CustomControl>) and import the FXML file
When doing all that it finally worked.

JavaFX error "null pointer Exception" when passing parameter from one Controller to another Controller

i have tried all solution in youtube and google but none of them work. The problem is when i want to switch to new scene along sending data to another scene i got error saying
Null pointer Exception
public class FirstController implements Initializable {
#FXML private TextField textField;
#FXML private Button btn;
#Override
public void initialize(URL arg0, ResourceBundle arg1) {
// TODO Auto-generated method stub
}
public void onClick(ActionEvent event){
//switching to new scene
FXMLLoader loader=new FXMLLoader();
loader.setLocation(getClass().getResource("/application/Second.fxml"));
try{
loader.load();
}catch(Exception e){ }
SecondController sn=loader.getController();
sn.setText(textField.getText());
Parent p=loader.getRoot();
Stage window=new Stage();
window.setScene(new Scene(p));
window.setTitle("dfd");
window.show();
}
}
main.fxml:
<AnchorPane prefHeight="450.0" prefWidth="650.0" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.Main">
<children>
<Button fx:id="btn" layoutX="285.0" layoutY="264.0" mnemonicParsing="false" onAction="#onClick" text="Button" />
<TextField fx:id="textField" layoutX="237.0" layoutY="213.0" />
</children>
</AnchorPane>
Second controller :
public class SecondController implements Initializable {
#FXML private Label labelField;
#Override
public void initialize(URL arg0, ResourceBundle arg1) {
// TODO Auto-generated method stub
}
public void setText(String name){
this.labelField.setText(name);
}
}
Second.fxml:
`<AnchorPane prefHeight="450.0" prefWidth="650.0" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1">
<children>
<Label fx:id="labelField" layoutX="297.0" layoutY="208.0" text="Label" />
</children>
</AnchorPane>

Your second FXML file is missing the fx:controller attribute. Therefore, when you load it, there is no controller, and so loader.getController() returns null.
Consequently, when you call sn.setText(...), you get a null pointer exception.
Just add the missing fx:controller attribute to the second FXML file. Assuming that SecondController is in the application package, this will look like:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.control.Label?>
<AnchorPane prefHeight="450.0" prefWidth="650.0" fx:controller="application.SecondController" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1">
<children>
<Label fx:id="labelField" layoutX="297.0" layoutY="208.0" text="Label" />
</children>
</AnchorPane>
Also note that it's very bad practice to silently "squash" exceptions, by using
try {
/* ... */
} catch (Exception e) { }
It's especially bad if the ensuing code depends on the code in the try block succeeding. In particular, in this case if your call to load() results in an exception (which may happen for a multitude of reasons, including the FXML not being found or being invalid, the fx:id and field names, or types,
not matching, method names for handlers not matching or having the wrong parameters, etc.), then the load method will silently fail and the controller will not be set in the loader. This will again result in sn being null.
Here's a complete example using your code, but with the other errors fixed as well as the missing fx:controller attribute inserted:
application/Main.java:
package application;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
Scene scene = new Scene(FXMLLoader.load(getClass().getResource("First.fxml")));
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
application/First.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.TextField?>
<AnchorPane prefHeight="450.0" prefWidth="650.0" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.FirstController">
<children>
<Button fx:id="btn" layoutX="285.0" layoutY="264.0" mnemonicParsing="false" onAction="#onClick" text="Button" />
<TextField fx:id="textField" layoutX="237.0" layoutY="213.0" />
</children>
</AnchorPane>
application/FirstController.java:
package application;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.stage.Stage;
public class FirstController implements Initializable {
#FXML private TextField textField;
#FXML private Button btn;
#Override
public void initialize(URL arg0, ResourceBundle arg1) {
// TODO Auto-generated method stub
}
public void onClick(ActionEvent event) throws Exception {
//switching to new scene
FXMLLoader loader=new FXMLLoader();
loader.setLocation(getClass().getResource("/application/Second.fxml"));
loader.load();
SecondController sn=loader.getController();
sn.setText(textField.getText());
Parent p=loader.getRoot();
Stage window=new Stage();
window.setScene(new Scene(p));
window.setTitle("dfd");
window.show();
}
}
application/Second.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.control.Label?>
<AnchorPane prefHeight="450.0" prefWidth="650.0" fx:controller="application.SecondController" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1">
<children>
<Label fx:id="labelField" layoutX="297.0" layoutY="208.0" text="Label" />
</children>
</AnchorPane>
application/SecondController.java
package application;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
public class SecondController implements Initializable {
#FXML private Label labelField;
#Override
public void initialize(URL arg0, ResourceBundle arg1) {
// TODO Auto-generated method stub
}
public void setText(String name){
this.labelField.setText(name);
}
}

JavaFX 8 FXML TextField (maybe other variables) are always null

I am practicing a small chat box window and I try to make it so the user must enter a name into the textfield box (a username) but I been having problems and I am sure this will not be the first time. I keep getting nullpointerexception every time I try to use one of the variables, for right now, it is textfield. So I initialize it but then it is always blank string even when I type in a username.
app.java
public class app extends Application {
#Override
public void start(Stage stage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("FXMLApp.fxml"));
Scene scene = new Scene(root);
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch();
}
}
FXMLApp.fxml (deleted what was not needed)
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.text.*?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<AnchorPane id="AnchorPane" maxHeight="900.0" maxWidth="800.0" minHeight="300.0" minWidth="200.0" prefHeight="600.0" prefWidth="500.0" xmlns="http://javafx.com/javafx/8.0.40" xmlns:fx="http://javafx.com/fxml/1" fx:controller="chatappclient.FXMLChatAppClientController">
<children>
<TextField fx:id="username" layoutX="176.0" layoutY="488.0" promptText="enter username" />
<Button fx:id="login" layoutX="176.0" layoutY="519.0" mnemonicParsing="false" onAction="#login" text="Login" />
</children>
</AnchorPane>
as you can see the login button calls
onAction="#login"
last file: FXMLAppController
package chatappclient;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.application.Platform;
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;
import javafx.scene.control.TextField;
import javafx.scene.layout.Pane;
import javax.swing.JOptionPane;
public class FXMLAppController implements Initializable
{
#FXML
private Pane top_container;
private Pane bottom_container;
private TextField username ;
private String name;
private Button login;
public FXMLChatAppClientController ()
{
// without this, I get nullpointerexception
// with it, the textfield is always null
username = new TextField();
}
#Override
public void initialize(URL url, ResourceBundle rb)
{}
#FXML
private void login()
{
// this returns empty string, if I did not initialize it, it would be an exception
System.out.println("DEBUG: " + username.getText());
}
}

You need to annotate each of the fields defined in the FXML file with #FXML:
private Pane top_container;
private Pane bottom_container;
#FXML
private TextField username ;
private String name;
#FXML
private Button login;

How do you change the label text in java using eclipse and scene builder?

I'm trying to make a "Hello World" using eclipse and scene builder.
package lj.HelloWorld;
import java.io.IOException;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
public class HelloWorld extends Application {
private Stage primaryStage;
private BorderPane rootLayout;
#Override
public void start(Stage primaryStage) {
this.primaryStage = primaryStage;
this.primaryStage.setTitle("AddressApp");
initRootLayout();
}
/**
* Initializes the root layout.
*/
public void initRootLayout() {
try {
// Load root layout from fxml file.
FXMLLoader loader = new FXMLLoader();
loader.setLocation(HelloWorld.class.getResource("rootHelloWorld.fxml"));
rootLayout = (BorderPane) loader.load();
// Show the scene containing the root layout.
Scene scene = new Scene(rootLayout);
primaryStage.setScene(scene);
primaryStage.show();
} catch (IOException e) {
e.printStackTrace();
}
}
// my attempt to refer to my label object in scenebuilder.
#FXML
private Label lblOutput;
#FXML
private void handleClick(ActionEvent event) {
lblOutput.setText("This");
}
}
And this is my fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.BorderPane?>
<BorderPane prefHeight="200.0" prefWidth="300.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1">
<center>
<Pane prefHeight="200.0" prefWidth="200.0" BorderPane.alignment="CENTER">
<children>
<Button fx:id="btnClick" layoutX="98.0" layoutY="14.0" mnemonicParsing="false" text="Click Me" />
<Label fx:id="lblOutput" layoutX="167.0" layoutY="18.0" text="1231231" />
</children>
</Pane>
</center>
</BorderPane>
I just want to know how to refer the the label and change its text to "Hello World".
PS: I'm from vb.net learning java. I've tried looking for a Hello World sample on google but some sites are down and others are just too complicated for me. Like the ch.makery tutorial.

You need a Controller class
package lj.HelloWorld;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.text.Text;
public class FXMLDocumentController {
#FXML private Label lblOutput;
#FXML protected void handleButtonAction(ActionEvent e){
lblOutput.setText("Hello World");
}
}
and tell your XML the controller class
<BorderPane fx:controller="lj.HelloWorld.FXMLDocumentController"
<Button fx:id="btnClick" layoutX="98.0" layoutY="14.0" mnemonicParsing="false" text="Click Me"
onAction="#handleButtonAction"/>
for detailed information and tutorial pls read this: http://docs.oracle.com/javafx/2/get_started/hello_world.htm

You can just try referring from the instance of the label for example:
lbl.setText("Hello World");

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.