We Keep Coding

Label not displaying text even after change (JavaFX)

I'm working on a project and I need to display the information of a Medicine object from a ListView to another Scene.
The user would select a Medicine from the ListView and press the Button to see it's details in the next Scene that would be displayed by Labels. The problem now is, I have transferred the info, and the text property of the Label has changed (observed through println and debugging), but the Label just won't display the changed text.
this is the main
package app;
import app.data.MedicineData;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.input.MouseEvent;
import javafx.stage.Stage;
import org.w3c.dom.events.Event;
import java.io.IOException;
public class Pharmachine extends Application {
public static final double WIDTH = 480;
public static final double HEIGHT = 720;
#Override
public void start(Stage stage) throws Exception{
Parent homePage = FXMLLoader.load(getClass().getResource("homepage.fxml"));
Scene homePageScene = newDefaultScene(homePage);
stage.setResizable(false);
stage.setScene(homePageScene);
stage.setTitle("Pharmachine");
stage.show();
}
#Override
public void init(){
MedicineData.getInstance().loadData();
}
public static Scene newDefaultScene(Parent parent){
Scene scene = new Scene(parent, WIDTH, HEIGHT);
scene.addEventHandler(MouseEvent.MOUSE_CLICKED,
(mouseEvent) -> {
Node targetNode = scene.getFocusOwner();
if(targetNode != null && targetNode.isFocused()) {
if(targetNode.getParent() != null)
targetNode.getParent().requestFocus();
mouseEvent.consume();
}
}
);
return scene;
}
public static void navigateTo(ActionEvent actionEvent, String filename){
Stage mainWindow = (Stage) ((Node) actionEvent.getSource()).getScene().getWindow();
Scene currentScene = ((Node) actionEvent.getSource()).getScene();
try {
currentScene.setRoot(FXMLLoader.load(Pharmachine.class.getResource(filename)));
mainWindow.setScene(currentScene);
} catch(IOException e){
e.printStackTrace();
}
}
public static void main(String[] args){ launch(args); }
}
this is the fxml for the list's page
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.ListView?>
<BorderPane xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml"
fx:controller="app.ListpageController" fx:id="pageRoot"
stylesheets="#styles/main.css">
<left>
<GridPane fx:id="listArea" alignment="CENTER">
<ListView fx:id="medicineList"
GridPane.rowIndex="1"/>
</GridPane>
</left>
<center>
<GridPane fx:id="buttonsArea" alignment="CENTER"
hgap="10" vgap="10">
<Button text="Back"
onAction="#displayHomePage"
GridPane.halignment="CENTER"/>
<Button text="Details"
onAction="#displayDetailsPage"
GridPane.rowIndex="1"
GridPane.halignment="CENTER"/>
</GridPane>
</center>
</BorderPane>
here is the controller for the list's page
package app;
import app.data.Medicine;
import app.data.MedicineData;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.control.Label;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Priority;
import javafx.util.Callback;
import java.io.IOException;
public class ListpageController {
#FXML
private BorderPane pageRoot;
#FXML
private GridPane listArea;
#FXML
private GridPane buttonsArea;
#FXML
private ListView<Medicine> medicineList;
#FXML public void initialize(){
listArea.setMaxWidth(Pharmachine.WIDTH * 3/5);
medicineList.setMinWidth(listArea.getMaxWidth());
medicineList.setMinHeight(Pharmachine.HEIGHT);
medicineList.setItems(MedicineData.getInstance().getMedicines());
medicineList.setCellFactory(new Callback<>() {
#Override
public ListCell<Medicine> call(ListView<Medicine> medicineListView) {
ListCell<Medicine> listCell = new ListCell<>(){
#Override
public void updateItem(Medicine medicine, boolean empty){
super.updateItem(medicine, empty);
if(!empty){
HBox medName = new HBox(new Label(medicine.getName()));
HBox.setHgrow(medName, Priority.ALWAYS);
HBox medPrice = new HBox(new Label(String.format("RM%.2f", medicine.getPrice())));
HBox medLabel = new HBox(medName, medPrice);
setGraphic(medLabel);
}
}
};
listCell.setOnMouseClicked(
(mouseEvent) -> {
if(mouseEvent.getClickCount() == 2){
medicineList.getSelectionModel().clearSelection();
}
}
);
return listCell;
}
});
}
#FXML private void displayHomePage(ActionEvent actionEvent){
Pharmachine.navigateTo(actionEvent, "homepage.fxml");
}
#FXML private void displayDetailsPage(ActionEvent actionEvent){
FXMLLoader loader = new FXMLLoader();
loader.setLocation(getClass().getResource("detailspage.fxml"));
try {
loader.load();
} catch(IOException e){
e.printStackTrace();
}
DetailspageController controller = loader.getController();
Medicine selectedMedicine = medicineList.getSelectionModel().getSelectedItem();
if(selectedMedicine != null) {
controller.setInfo(selectedMedicine);
Pharmachine.navigateTo(actionEvent, "detailspage.fxml");
}
}
}
this is the fxml for the next scene (just simple for now)
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.BorderPane?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.text.Text?>
<BorderPane xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml"
fx:id="pageRoot" fx:controller="app.DetailspageController"
stylesheets="#styles/main.css">
<center>
<GridPane fx:id="detailsArea"
alignment="CENTER" hgap="10" vgap="10">
<Label text="Details"/>
<Text text="Name: "
GridPane.rowIndex="1"/>
<Label fx:id="medNameLabel" text="~"
GridPane.rowIndex="1" GridPane.columnIndex="1"/>
<Text text="Price: "
GridPane.rowIndex="2"/>
<Label fx:id="medPriceLabel" text="~"
GridPane.rowIndex="2" GridPane.columnIndex="1"/>
</GridPane>
</center>
</BorderPane>
and this is the scene's controller
package app;
import app.data.Medicine;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import java.net.URL;
import java.util.ResourceBundle;
public class DetailspageController implements Initializable {
private Medicine selectedMedicine;
#FXML
private BorderPane pageRoot;
#FXML
private GridPane detailsArea;
#FXML
private Label medNameLabel;
#FXML
private Label medPriceLabel;
#Override
public void initialize(URL url, ResourceBundle rb){
}
public void setInfo(Medicine medicine){
selectedMedicine = medicine;
medNameLabel.setText(selectedMedicine.getName());
medPriceLabel.setText(String.format("RM%.2f", selectedMedicine.getPrice()));
System.out.println(medNameLabel.textProperty());
System.out.println(medNameLabel.getText());
medNameLabel.setStyle("-fx-background-color: red;");
}
}
The help would mean a lot. Thank you :]

In your displayDetailsPage method, you load a scene from detailspage.fxml, and you update its labels by calling the setInfo method of the controller.
Then, you call Pharmachine.navigateTo, which loads detailspage.xml again and replaces the scene root with the newly loaded root. You updated the text of the labels in the first details page, but the second details page is brand new, so it doesn’t have those changes.
The second argument in the navigateTo method should be of type Parent rather than a String. navigateTo should not attempt to load any .fxml file; let that be the caller’s responsibility.
Side note: When a list has multiple attributes for each data item, you should probably use a TableView rather than a ListView.

JavaFX/FXML: TableView correctly refreshing in case of editing items, but not in case of removing items (ArrayList->TableView)

I'm working on a larger project (together with quite a number of fellow students), and I'm trying to display an arrayList (which type we're using over and over again in our project, so I wouldn't love to change all these to ObservableLists just for my rather small issue) in a TableView.
I've created a smaller project just in order to get to the heart of the problem and to show you:
In the class editMyGrades (together with an fxml file of the same name) I want to display my SUBJECTs (-> String subjectName), each one with its GRADE (-> int grade) in a TableView.
Initializing the parent root and the tableView the ArrayList subjects is transformed to an ObservableList, which is loaded into the TableView.
I really would like to understand theoretically, why changing GRADEs works with the tableView, but removing doesn't, and to know what to do about it practically ;-)
Thank you very much in advance!
Main class:
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import java.util.ArrayList;
public class Main extends Application {
private static ArrayList<Subject> subjects = new ArrayList<>();
public static ArrayList<Subject> getSubjects () {return subjects;}
// private static ObservableList<Subject> subjects = FXCollections.observableArrayList();
// public static ObservableList<Subject> getSubjects () {return subjects;}
public static void main (String[] args) {
subjects.add(new Subject("computer science", 2));
subjects.add(new Subject("literature", 4));
launch (args);
}
public void start (Stage primaryStage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("/editMyGrades.fxml"));
Scene scene = new Scene(root);
primaryStage.setScene(scene);
primaryStage.show();
}
}
Class Subject:
public class Subject {
private String subjectName;
private int grade;
public Subject (String subjectName, int grade) {
this.subjectName = subjectName;
this.grade = grade;
}
public String getSubjectName () {return subjectName;}
public int getGrade () {return grade;}
public void setGrade (int grade) {this.grade = grade;}
}
controlling class editMyGrades:
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.input.MouseEvent;
import java.util.ArrayList;
public class editMyGrades {
Subject subjectToEdit;
#FXML
private TableView<Subject> tableView;
#FXML
private TableColumn<Subject, String> subjectCol;
#FXML
private TableColumn<Subject, Number> gradeCol;
#FXML
private TextField textField;
#FXML
private Button changeButton;
#FXML
private Button deleteButton;
#FXML
public void initialize() {
subjectCol.setCellValueFactory(new PropertyValueFactory<>("subjectName"));
gradeCol.setCellValueFactory(new PropertyValueFactory<>("grade"));
//tableView.setItems (FXCollections.observableArrayList(Main.getSubjects()));
ObservableList<Subject> subjects = FXCollections.observableArrayList(Main.getSubjects());
tableView.setItems(subjects);
}
#FXML
private void tableViewClicked(MouseEvent event) {
if (event.getClickCount() == 2) {
subjectToEdit = tableView.getSelectionModel().getSelectedItem();
textField.setText ("" + tableView.getSelectionModel().getSelectedItem().getGrade());
}
}
#FXML
private void change(ActionEvent event) {
subjectToEdit.setGrade(Integer.parseInt(textField.getText()));
textField.clear();
tableView.refresh();
}
#FXML
private void delete (ActionEvent event) {
Subject selectedSubject = tableView.getSelectionModel().getSelectedItem();
ArrayList<Subject> subjects = Main.getSubjects();
subjects.remove(selectedSubject);
tableView.refresh();
}
}
editingMyGrades.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>
<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="editMyGrades">
<children>
<Label text="change your grades!" />
<HBox>
<children>
<TableView fx:id="tableView" onMouseClicked="#tableViewClicked" prefHeight="200.0" prefWidth="518.0">
<columns>
<TableColumn fx:id="subjectCol" prefWidth="262.0" text="subject" />
<TableColumn fx:id="gradeCol" minWidth="0.0" prefWidth="146.0" text="grade" />
</columns>
</TableView>
<VBox alignment="CENTER">
<children>
<Button mnemonicParsing="false" onAction="#delete" text="deleteButton" />
</children>
</VBox>
</children>
</HBox>
<TextField fx:id="textField" maxWidth="100.0" />
<Button fx:id="changeButton" mnemonicParsing="false" onAction="#change" text="Change!" />
</children>
</VBox>

When working with JavaFX it's good practice to always use FXCollections.
When you make a modification to the ArrayList, the changes are not generating list change nofications. You must get the ObservableList from the tableview and perform the operations on it since it is the wrapper (the smart list) that is backed by your ArrayList.

Thank you indeed for your explanations! In fact in my real problem I'm using MVC, but the Controller object is located in the main - static -, and as it appears, it can't be done in other way. For the illustration of my problem I thought id wouldn't make a difference, if I had a static controller object with the list or just the list itself (perhaps I was wrong ...).
Now, having tried to apply everything you told me, it's just the other way around: the tableView displays removements, but no changes.
just the fxml control class EditMyGrades:
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.input.MouseEvent;
public class EditMyGrades {
private ObservableList<Subject> subjects = FXCollections.observableArrayList();
private Subject subjectToEdit;
#FXML
private TableView<Subject> tableView;
#FXML
private TableColumn<Subject, String> subjectCol;
#FXML
private TableColumn<Subject, Number> gradeCol;
#FXML
private TextField textField;
#FXML
private Button changeButton;
#FXML
private Button deleteButton;
#FXML
public void initialize() {
subjectCol.setCellValueFactory(new PropertyValueFactory<>("subjectName"));
gradeCol.setCellValueFactory(new PropertyValueFactory<>("grade"));
subjects.add(new Subject("computer science", 2));
subjects.add(new Subject("literature", 4));
tableView.setItems(subjects);
}
#FXML
private void tableViewClicked(MouseEvent event) {
if (event.getClickCount() == 2) {
subjectToEdit = tableView.getSelectionModel().getSelectedItem();
textField.setText ("" + tableView.getSelectionModel().getSelectedItem().getGrade());
}
}
#FXML
private void change(ActionEvent event) {
subjectToEdit.setGrade(Integer.parseInt(textField.getText()));
textField.clear();
}
#FXML
private void delete (ActionEvent event) {
ObservableList<Subject> subjects = tableView.getItems();
Subject selectedSubject = tableView.getSelectionModel().getSelectedItem();
subjects.remove(selectedSubject);
}
}

NullPointerException Setting ComboBox From FXML [duplicate]

I'm really struggling to understand JavaFX controllers, my aim is to write to a TextArea to act as a log.
My code is below, but I want to be able to change values ETC from another class that I can call when needed. I have tried to create a controller class that extents Initializable but i cant get it to work. Could some one steer me in the correct direction?
I want to move the #FXML code at the bottom to another class and it update the Scene.
package application;
import javafx.event.ActionEvent;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import java.io.IOException;
import javafx.application.Application;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;
public class Main extends Application {
#Override
public void start(Stage primaryStage) {
try {
Parent root = FXMLLoader.load(getClass().getResource("Root.fxml"));
Scene scene = new Scene(root,504,325);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
public Thread thread = new Thread(new webimporter());
#FXML
public Label runningLabel;
#FXML
public TextArea txtArea;
#FXML
void runClick(ActionEvent event) throws IOException{
changeLabelValue("Importer running...");
thread.start();
}
#FXML
protected void stopClick(ActionEvent event){
changeLabelValue("Importer stopped...");
thread.interrupt();
}
#FXML
void changeLabelValue(String newText){
runningLabel.setText(newText);
}
void changeTextAreaValue(String newText1){
txtArea.setText(newText1);
}
}

Don't make the Application class a controller. It's a sin. There are other questions and answers which address this, but my search skills cannot find them at this time.
The reason it is a sin is:
You are only supposed to have one Application instance, and, by default, the loader will make a new instance, so you end up with two application objects.
Referencing the member objects is confusing, because the original launched application doesn't have the #FXML injected fields, but the loader created application instance does have #FXML inject fields.
Also, unrelated advice: Don't start trying to write multi-threaded code until you have the application at least working to the extent where it displays your UI.
A multi-threaded logger for JavaFX is in the answer to Most efficient way to log messages to JavaFX TextArea via threads with simple custom logging frameworks, though unfortunately it is not straight-forward in its implementation and comes with little documentation.
textlogger/Root.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefWidth="400.0" spacing="10.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="textlogger.ImportController">
<children>
<HBox alignment="BASELINE_LEFT" minHeight="-Infinity" minWidth="-Infinity" spacing="10.0">
<children>
<Button mnemonicParsing="false" onAction="#run" text="Run" />
<Button mnemonicParsing="false" onAction="#stop" text="Stop" />
<Label fx:id="runningLabel" />
</children>
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</padding>
</HBox>
<TextArea fx:id="textArea" editable="false" prefHeight="200.0" prefWidth="200.0" />
</children>
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</padding>
</VBox>
textlogger.ImportController.java
package textlogger;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import java.io.IOException;
public class ImportController {
#FXML
private Label runningLabel;
#FXML
private TextArea textArea;
private WebImporter importer;
#FXML
void run(ActionEvent event) throws IOException {
changeLabelValue("Importer running...");
if (importer == null) {
importer = new WebImporter(textArea);
Thread thread = new Thread(
importer
);
thread.setDaemon(true);
thread.start();
}
}
#FXML
void stop(ActionEvent event){
changeLabelValue("Importer stopped...");
if (importer != null) {
importer.cancel();
importer = null;
}
}
private void changeLabelValue(String newText){
runningLabel.setText(newText);
}
}
textlogger.WebImporter.java
import javafx.application.Platform;
import javafx.concurrent.Task;
import javafx.scene.control.TextArea;
import java.time.LocalTime;
public class WebImporter extends Task<Void> {
private final TextArea textArea;
public WebImporter(TextArea textArea) {
this.textArea = textArea;
}
#Override
protected Void call() throws Exception {
try {
while (!isCancelled()) {
Thread.sleep(500);
Platform.runLater(
() -> textArea.setText(
textArea.getText() + LocalTime.now() + "\n"
)
);
}
} catch (InterruptedException e) {
Thread.interrupted();
}
return null;
}
}
textlogger.TextLoggingSample.java
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class TextLoggingSample extends Application {
#Override
public void start(Stage stage) {
try {
FXMLLoader loader = new FXMLLoader();
Parent root = loader.load(
getClass().getResourceAsStream(
"Root.fxml"
)
);
Scene scene = new Scene(root);
stage.setScene(scene);
stage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
}

Are controller nodes always null inside setOnCloseRequest? [duplicate]

I'm really struggling to understand JavaFX controllers, my aim is to write to a TextArea to act as a log.
My code is below, but I want to be able to change values ETC from another class that I can call when needed. I have tried to create a controller class that extents Initializable but i cant get it to work. Could some one steer me in the correct direction?
I want to move the #FXML code at the bottom to another class and it update the Scene.
package application;
import javafx.event.ActionEvent;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import java.io.IOException;
import javafx.application.Application;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;
public class Main extends Application {
#Override
public void start(Stage primaryStage) {
try {
Parent root = FXMLLoader.load(getClass().getResource("Root.fxml"));
Scene scene = new Scene(root,504,325);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
public Thread thread = new Thread(new webimporter());
#FXML
public Label runningLabel;
#FXML
public TextArea txtArea;
#FXML
void runClick(ActionEvent event) throws IOException{
changeLabelValue("Importer running...");
thread.start();
}
#FXML
protected void stopClick(ActionEvent event){
changeLabelValue("Importer stopped...");
thread.interrupt();
}
#FXML
void changeLabelValue(String newText){
runningLabel.setText(newText);
}
void changeTextAreaValue(String newText1){
txtArea.setText(newText1);
}
}

Don't make the Application class a controller. It's a sin. There are other questions and answers which address this, but my search skills cannot find them at this time.
The reason it is a sin is:
You are only supposed to have one Application instance, and, by default, the loader will make a new instance, so you end up with two application objects.
Referencing the member objects is confusing, because the original launched application doesn't have the #FXML injected fields, but the loader created application instance does have #FXML inject fields.
Also, unrelated advice: Don't start trying to write multi-threaded code until you have the application at least working to the extent where it displays your UI.
A multi-threaded logger for JavaFX is in the answer to Most efficient way to log messages to JavaFX TextArea via threads with simple custom logging frameworks, though unfortunately it is not straight-forward in its implementation and comes with little documentation.
textlogger/Root.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefWidth="400.0" spacing="10.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="textlogger.ImportController">
<children>
<HBox alignment="BASELINE_LEFT" minHeight="-Infinity" minWidth="-Infinity" spacing="10.0">
<children>
<Button mnemonicParsing="false" onAction="#run" text="Run" />
<Button mnemonicParsing="false" onAction="#stop" text="Stop" />
<Label fx:id="runningLabel" />
</children>
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</padding>
</HBox>
<TextArea fx:id="textArea" editable="false" prefHeight="200.0" prefWidth="200.0" />
</children>
<padding>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</padding>
</VBox>
textlogger.ImportController.java
package textlogger;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import java.io.IOException;
public class ImportController {
#FXML
private Label runningLabel;
#FXML
private TextArea textArea;
private WebImporter importer;
#FXML
void run(ActionEvent event) throws IOException {
changeLabelValue("Importer running...");
if (importer == null) {
importer = new WebImporter(textArea);
Thread thread = new Thread(
importer
);
thread.setDaemon(true);
thread.start();
}
}
#FXML
void stop(ActionEvent event){
changeLabelValue("Importer stopped...");
if (importer != null) {
importer.cancel();
importer = null;
}
}
private void changeLabelValue(String newText){
runningLabel.setText(newText);
}
}
textlogger.WebImporter.java
import javafx.application.Platform;
import javafx.concurrent.Task;
import javafx.scene.control.TextArea;
import java.time.LocalTime;
public class WebImporter extends Task<Void> {
private final TextArea textArea;
public WebImporter(TextArea textArea) {
this.textArea = textArea;
}
#Override
protected Void call() throws Exception {
try {
while (!isCancelled()) {
Thread.sleep(500);
Platform.runLater(
() -> textArea.setText(
textArea.getText() + LocalTime.now() + "\n"
)
);
}
} catch (InterruptedException e) {
Thread.interrupted();
}
return null;
}
}
textlogger.TextLoggingSample.java
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class TextLoggingSample extends Application {
#Override
public void start(Stage stage) {
try {
FXMLLoader loader = new FXMLLoader();
Parent root = loader.load(
getClass().getResourceAsStream(
"Root.fxml"
)
);
Scene scene = new Scene(root);
stage.setScene(scene);
stage.show();
} catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
}

the controller "classname" has no event slot "methodname"

I am getting this error
the controller "classname" has no event slot "methodname"
if i add "/" before application in fx:controller="application.MainController">
this error goes but creates
class failed to load
/Users/myname/Documents/workspace/Javafx%20tesr/bin/application/Main.fxml:7
here's the xml file
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane prefHeight="450" prefWidth="500" xmlns="http://javafx.com/javafx/8.0.65" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.MainController">
<children>
<Button fx:id="genratebutton" layoutX="160.0" layoutY="225.0" mnemonicParsing="false" onAction="#generaterandom" prefHeight="27.0" prefWidth="180.0" text="generate random" />
<Label fx:id="myMessage" layoutX="138.0" layoutY="104.0" prefHeight="89.0" prefWidth="225.0" />
</children>
</AnchorPane>
(sorry new to GUI only know basics of swing)
this is main class
package application;
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) {
try {
Parent root=FXMLLoader.load(getClass().getClassLoader().getResource("/Main.fxml"));
Scene scene = new Scene(root,400,400);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.show();
}
catch(Exception e) {
e.printStackTrace();
System.exit(0);
}
}
public static void main(String[] args) {
launch(args);
}
}
this is another class whose method i want to invoke
package application;
import java.util.Random;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Label;
public class MainController {
#FXML
private Label myMessage;
void generaterandom (ActionEvent event){
Random rand=new Random();
int myrand=rand.nextInt(50)+1;
myMessage.setText(Integer.toString(myrand));
System.out.println(Integer.toString(myrand));
}
}

Since the controller method is not public, you need to annotate it #FXML:
public class MainController {
#FXML
private Label myMessage;
#FXML
void generaterandom (ActionEvent event){
Random rand=new Random();
int myrand=rand.nextInt(50)+1;
myMessage.setText(Integer.toString(myrand));
System.out.println(Integer.toString(myrand));
}
}