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);
    }
}