Using JavaFX controller without FXML

Question

Is there a possibility to use a controller with a JavaFX GUI without using FXML.

I noticed that the FXML file contains an fx-controller attribute to bind the controller but i don't find it an easy way to work with it.

Any ideas about have an MVC arch with JavaFX without using the FXML file or JavaFX Scene Builder ?

Answer 1

Your question isn't particularly clear to me: you just create the classes and basically tie everything together with listeners. I don't know if this helps, but here is a simple example that just has a couple of text fields and a label displaying their sum. This is what I regard as "classical MVC": the view observes the model and updates the UI elements if the model changes. It registers handlers with the UI elements and delegates to the controller if events happen: the controller in turn processes the input (if necessary) and updates the model.

Model:

package mvcexample;

import javafx.beans.property.IntegerProperty;
import javafx.beans.property.ReadOnlyIntegerWrapper;
import javafx.beans.property.SimpleIntegerProperty;

public class AdditionModel {
    private final IntegerProperty x = new SimpleIntegerProperty();
    private final IntegerProperty y = new SimpleIntegerProperty();
    private final ReadOnlyIntegerWrapper sum = new ReadOnlyIntegerWrapper();

    public AdditionModel() {
        sum.bind(x.add(y));
    }

    public final IntegerProperty xProperty() {
        return this.x;
    }

    public final int getX() {
        return this.xProperty().get();
    }

    public final void setX(final int x) {
        this.xProperty().set(x);
    }

    public final IntegerProperty yProperty() {
        return this.y;
    }

    public final int getY() {
        return this.yProperty().get();
    }

    public final void setY(final int y) {
        this.yProperty().set(y);
    }

    public final javafx.beans.property.ReadOnlyIntegerProperty sumProperty() {
        return this.sum.getReadOnlyProperty();
    }

    public final int getSum() {
        return this.sumProperty().get();
    }



}

Controller:

package mvcexample;

public class AdditionController {

    private final AdditionModel model ;

    public AdditionController(AdditionModel model) {
        this.model = model ;
    }

    public void updateX(String x) {
        model.setX(convertStringToInt(x));
    }

    public void updateY(String y) {
        model.setY(convertStringToInt(y));
    }

    private int convertStringToInt(String s) {
        if (s == null || s.isEmpty()) {
            return 0 ;
        }
        if ("-".equals(s)) {
            return 0 ;
        }
        return Integer.parseInt(s);
    }
}

View:

package mvcexample;

import javafx.geometry.HPos;
import javafx.geometry.Pos;
import javafx.scene.Parent;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.control.TextFormatter;
import javafx.scene.control.TextFormatter.Change;
import javafx.scene.layout.ColumnConstraints;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.Priority;

public class AdditionView {
    private GridPane view ;
    private TextField xField;
    private TextField yField;
    private Label sumLabel;

    private AdditionController controller ;
    private AdditionModel model ;

    public AdditionView(AdditionController controller, AdditionModel model) {

        this.controller = controller ;
        this.model = model ;

        createAndConfigurePane();

        createAndLayoutControls();

        updateControllerFromListeners();

        observeModelAndUpdateControls();

    }

    public Parent asParent() {
        return view ;
    }

    private void observeModelAndUpdateControls() {
        model.xProperty().addListener((obs, oldX, newX) -> 
                updateIfNeeded(newX, xField));

        model.yProperty().addListener((obs, oldY, newY) -> 
                updateIfNeeded(newY, yField));

        sumLabel.textProperty().bind(model.sumProperty().asString());
    }

    private void updateIfNeeded(Number value, TextField field) {
        String s = value.toString() ;
        if (! field.getText().equals(s)) {
            field.setText(s);
        }
    }

    private void updateControllerFromListeners() {
        xField.textProperty().addListener((obs, oldText, newText) -> controller.updateX(newText));
        yField.textProperty().addListener((obs, oldText, newText) -> controller.updateY(newText));
    }

    private void createAndLayoutControls() {
        xField = new TextField();
        configTextFieldForInts(xField);

        yField = new TextField();
        configTextFieldForInts(yField);

        sumLabel = new Label();

        view.addRow(0, new Label("X:"), xField);
        view.addRow(1, new Label("Y:"), yField);
        view.addRow(2, new Label("Sum:"), sumLabel);
    }

    private void createAndConfigurePane() {
        view = new GridPane();

        ColumnConstraints leftCol = new ColumnConstraints();
        leftCol.setHalignment(HPos.RIGHT);
        leftCol.setHgrow(Priority.NEVER);

        ColumnConstraints rightCol = new ColumnConstraints();
        rightCol.setHgrow(Priority.SOMETIMES);

        view.getColumnConstraints().addAll(leftCol, rightCol);

        view.setAlignment(Pos.CENTER);
        view.setHgap(5);
        view.setVgap(10);
    }

    private void configTextFieldForInts(TextField field) {
        field.setTextFormatter(new TextFormatter<Integer>((Change c) -> {
            if (c.getControlNewText().matches("-?\\d*")) {
                return c ;
            }
            return null ;
        }));
    }
}

Application class:

package mvcexample;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class MVCExample extends Application {

    @Override
    public void start(Stage primaryStage) {
        AdditionModel model = new AdditionModel();
        AdditionController controller = new AdditionController(model);
        AdditionView view = new AdditionView(controller, model);

        Scene scene = new Scene(view.asParent(), 400, 400);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

Answer 2

I use JavaFX extensively and do not use FXML or scenebuilder. So I can vouch that it can be done.

Below is the auto generated code made by my IDE to get an JavaFX main class. This will be the root of your application. You will then add to it to create your application.

public class NewFXMain extends Application {

@Override
public void start(Stage primaryStage) {
    Button btn = new Button();
    btn.setText("Say 'Hello World'");
    btn.setOnAction(new EventHandler<ActionEvent>() {

        @Override
        public void handle(ActionEvent event) {
            System.out.println("Hello World!");
        }
    });

    StackPane root = new StackPane();
    root.getChildren().add(btn);

    Scene scene = new Scene(root, 300, 250);

    primaryStage.setTitle("Hello World!");
    primaryStage.setScene(scene);
    primaryStage.show();
}

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    launch(args);
}

}