JavaFX - MVVM - TextField Binding

TextFieldBinding.java

import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class TextFieldBinding extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        var controller = new Controller();
        var scene = new Scene(controller.getVBox(), 200, 200);
        primaryStage.setScene(scene);
        primaryStage.setTitle("TextField Binding");
        primaryStage.setResizable(false);
        primaryStage.show();
    }

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

class Controller {
    private final VBox vBox = new VBox();
    private final ViewModel viewModel = new ViewModel();

    Controller() {
        this.initialize();
    }

    public VBox getVBox() {
        return vBox;
    }

    void initialize() {
        var filterLabel = new Label("Filter: ");
        var filterTextField = new TextField();
        filterTextField.textProperty().bindBidirectional(this.viewModel.filterStringProperty());
        filterTextField.textProperty().addListener((observable, oldValue, newValue) -> this.viewModel.filter());
        var hBox1 = new HBox(filterLabel, filterTextField);

        var resultLabel = new Label("Result: ");
        var result = new Text();
        result.textProperty().bind(this.viewModel.resultProperty());
        var hBox2 = new HBox(resultLabel, result);

        this.vBox.getChildren().add(hBox1);
        this.vBox.getChildren().add(hBox2);
    }
}

class ViewModel {
    private final StringProperty filterString = new SimpleStringProperty();
    private final StringProperty result = new SimpleStringProperty();

    public String getFilterString() {
        return filterString.get();
    }

    public StringProperty filterStringProperty() {
        return filterString;
    }

    public String getResult() {
        return result.get();
    }

    public StringProperty resultProperty() {
        return result;
    }

    public void filter() {
        var value = this.filterString.getValue();
        System.out.println("Filter String: " + value);
        this.result.setValue(value);
    }
}