Share the same reusable FXML component in multiple views - javafx

Question

I have a FXML view that contains a TabView with multiple tabs.
Every Tab has it's own FXML component + controller.
I would like all tabs to report progress via a component defined defined in the main view.
I know that I can inject child controllers into the main controller via FXML.
But to my current understanding, I need to access the parent controller inside my child controllers since the component is located in the main view.
I can also access the child controllers inside the initialize method of my main view. If I follow this path, I would need to modify the child controllers to set the shared component.
This is suboptimal, since the child components would be dependent on a main view that is performing those changes.
I created a MWE to illustrate the dilemma.
The question in short:
How can I report progress of Service1 and Service2 to the progressAndStatusGrid in the main view?
Callenge in short:
Make this application not throw a NPE and report progress to the progress component ;)
MWE:
Launcher:
package org.example;
public class Launcher {
public static void main(final String[] args) {
SimpleApplication.main(args);
}
}
Application:
package org.example;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class SimpleApplication extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("/fxml/MainView.fxml"));
#SuppressWarnings("unused")
MainViewController controller = fxmlLoader.getController();
final Parent root = fxmlLoader.load();
final Scene scene = new Scene(root);
primaryStage.setTitle("Hello World");
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
Application.launch(args);
}
}
MainController:
package org.example;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.layout.GridPane;
import java.net.URL;
import java.util.ResourceBundle;
public class MainViewController implements Initializable {
#FXML
GridPane progressAndStatusGrid;
#Override
public void initialize(URL url, ResourceBundle resourceBundle) {
}
}
MainView:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Tab?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.layout.BorderPane?>
<BorderPane prefHeight="150.0" prefWidth="350.0" xmlns="http://javafx.com/javafx/17.0.2-ea"
xmlns:fx="http://javafx.com/fxml/1" fx:controller="org.example.MainViewController">
<padding>
<Insets top="4" right="4" bottom="4" left="4"/>
</padding>
<top>
</top>
<center>
<TabPane>
<Tab text="tab1" closable="false">
<fx:include fx:id="tab1" source="Tab1View.fxml"/>
</Tab>
<Tab text="tab2" closable="false">
<fx:include fx:id="tab2" source="Tab2View.fxml"/>
</Tab>
</TabPane>
</center>
<bottom>
<fx:include fx:id="progressAndStatusGrid"
source="ProgressAndStatusGridComponent.fxml"/>
</bottom>
</BorderPane>
"Shared" componentController:
package org.example;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.control.ProgressBar;
import javafx.scene.layout.HBox;
import java.net.URL;
import java.util.ResourceBundle;
public class ProgressAndStatusGridComponentController implements Initializable {
#FXML
ProgressBar progressBar;
#FXML
HBox progressStatusBox;
#FXML
Label progressLabel;
#Override
public void initialize(URL url, ResourceBundle resourceBundle) {
}
}
"Shared" componentView:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.ProgressBar?>
<?import javafx.scene.layout.*?>
<GridPane xmlns="http://javafx.com/javafx"
xmlns:fx="http://javafx.com/fxml"
fx:controller="org.example.ProgressAndStatusGridComponentController"
hgap="4" vgap="4">
<padding>
<Insets top="4" right="4" bottom="4" left="4"/>
</padding>
<fx:define>
<ColumnConstraints fx:id="colConstraints2" percentWidth="100"/>
</fx:define>
<columnConstraints>
<fx:reference source="colConstraints2"/>
<fx:reference source="colConstraints2"/>
</columnConstraints>
<ProgressBar fx:id="progressBar" GridPane.columnIndex="0" GridPane.rowIndex="0"/>
<HBox fx:id="progressStatusBox" alignment="CENTER" spacing="4" GridPane.columnIndex="1" GridPane.rowIndex="0">
<padding>
<Insets top="4" right="4" bottom="4" left="4"/>
</padding>
<Label fx:id="progressLabel"/>
</HBox>
</GridPane>
Tab1Controller:
package org.example;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import java.net.URL;
import java.util.ResourceBundle;
public class Tab1Controller implements Initializable {
#FXML
Button button1;
Service1 service1 = new Service1();
// How to get a reference, that is already initialized?
#FXML
ProgressAndStatusGridComponentController progressAndStatusGridComponentController;
#Override
public void initialize(URL url, ResourceBundle resourceBundle) {
button1.disableProperty().bind(service1.runningProperty());
}
public void handleButtonClick(ActionEvent actionEvent) {
service1.cancel();
service1.reset();
progressAndStatusGridComponentController.progressBar.progressProperty().bind(service1.progressProperty());
progressAndStatusGridComponentController.progressLabel.textProperty().bind(service1.messageProperty());
service1.start();
}
}
Tab1View:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.BorderPane?>
<BorderPane xmlns="http://javafx.com/javafx"
xmlns:fx="http://javafx.com/fxml"
fx:controller="org.example.Tab1Controller">
<center>
<Button fx:id="button1" text="Start Background Progress #1" onAction="#handleButtonClick"/>
</center>
</BorderPane>
Tab2Controller:
package org.example;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import java.net.URL;
import java.util.ResourceBundle;
public class Tab2Controller implements Initializable {
#FXML
Button button2;
Service2 service2 = new Service2();
// How to get a reference, that is already initialized?
#FXML
ProgressAndStatusGridComponentController progressAndStatusGridComponentController;
#Override
public void initialize(URL url, ResourceBundle resourceBundle) {
button2.disableProperty().bind(service2.runningProperty());
}
public void handleButtonClick(ActionEvent actionEvent) {
service2.cancel();
service2.reset();
progressAndStatusGridComponentController.progressBar.progressProperty().bind(service2.progressProperty());
progressAndStatusGridComponentController.progressLabel.textProperty().bind(service2.messageProperty());
service2.start();
}
}
Tab2View:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.BorderPane?>
<BorderPane xmlns="http://javafx.com/javafx"
xmlns:fx="http://javafx.com/fxml"
fx:controller="org.example.Tab2Controller">
<center>
<Button fx:id="button2" text="Start Background Progress #2" onAction="#handleButtonClick"/>
</center>
</BorderPane>
Service1:
package org.example;
import javafx.concurrent.Service;
import javafx.concurrent.Task;
public class Service1 extends Service<Void> {
static final int workLoad = 100;
#Override
protected Task<Void> createTask() {
return new Task<>() {
#Override
protected Void call() throws Exception {
updateMessage("Starting Task #1..");
for (int i = 0; i < workLoad; i++) {
Thread.sleep(200);
updateProgress(i, workLoad);
updateMessage(i + " elements done");
}
updateMessage("Task #1 done!");
return null;
}
};
}
}
Service2:
package org.example;
import javafx.concurrent.Service;
import javafx.concurrent.Task;
public class Service2 extends Service<Void> {
static final int workLoad = 100;
#Override
protected Task<Void> createTask() {
return new Task<>() {
#Override
protected Void call() throws Exception {
updateMessage("Starting Task #2..");
for (int i = 0; i < workLoad; i++) {
Thread.sleep(200);
updateProgress(i, workLoad);
updateMessage(i + " elements done");
}
updateMessage("Task #2 done!");
return null;
}
};
}
}