How to attach event handlers to controller in MVC | JavaFX - javafx

Question

I am having trouble understanding how to apply the mvc pattern with JavaFX.
Here are my questions with respect to the code below, since I need to follow the pattern given in the code:
a) How can I attach an event handler of the button which is present in my ViewA to the code in my ControllerA (specifically, attachEventHandlers() method). For example, I want my button to populate the comboBox in ViewA with the results of getModelItems() method from controller.
Note that the method getModelItems() is private.
b) I would have multiple buttons and event handlers in my view. How will I bind each one of them uniquely to the controller?
c) I want to invoke setName(String name) on my model in the controller, and the parameter I want to pass is the selected value on the comboBox in viewA. How can I achieve this?
Thank you so much for any help!
Below is the code referred in the description.
Controller:
import model.ModelA;
import view.ViewA;
public class ControllerA {
private ViewA view;
private ModelA model;
public ControllerA(ViewA view, ModelA model) {
//initialise model and view fields
this.model = model;
this.view = view;
//populate combobox in ViewB, e.g. if viewB represented your ViewB you could invoke the line below
//viewB.populateComboBoxWithCourses(setupAndRetrieveCourses());
this.attachEventHandlers();
}
private void attachEventHandlers() {
}
private String[] getModelItems() {
String[] it = new String[2];
it[0] = "0";
it[1] = "1";
return it;
}
}
Model:
public class ModelA {
private String name;
public Name() {
name = "";
}
public void setName(String name) {
this.name = name;
}
#Override
public String toString() {
return "Name = " + name;
}
}
View:
import javafx.scene.layout.BorderPane;
//You may change this class to extend another type if you wish
public class ViewA extends BorderPane {
public BorderPane bp;
public ViewA(){
this.bp = new BorderPane();
ComboBox comboBox = new ComboBox();
Button button1 = new Button("Populate");
bp.setTop(button1);
bp.setBottom(comboBox);
}
}
Loader:
public class ApplicationLoader extends Application {
private ViewA view;
#Override
public void init() {
//create model and view and pass their references to the controller
ModelA model = new ModelA();
view = new ViewA();
new ControllerA(view, model);
}
#Override
public void start(Stage stage) throws Exception {
//whilst you can set a min width and height (example shown below) for the stage window,
//you should not set a max width or height and the application should
//be able to be maximised to fill the screen and ideally behave sensibly when resized
stage.setMinWidth(530);
stage.setMinHeight(500);
stage.setTitle("Final Year Module Chooser Tool");
stage.setScene(new Scene(view));
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}

Answer 1

You add delegates to your ViewA to allow for access:
public class ViewA extends BorderPane {
ComboBox comboBox;
Button button1;
public ViewA(){
comboBox = new ComboBox();
button1 = new Button("Populate");
setTop(button1);
setBottom(comboBox);
}
// Add delegates for all functionality you want to make available through ViewA
public ObservableList<String> getItems() { return comboBox.getItems(); }
public void setOnButton1Action(...) { ... }
public void setOnButton2Action(...) { ... }
...
}
You can go as broad or as narrow as you like, based on how much you want to manage through ViewA.