Javafx app with many pages

Question

I've got a question about building a gui in javafx.

When I build a program with many pages, I mean for example - The start page contains a couple of buttons "Add user", "Drop user", "Change user data" - each of these buttons draws an different panel. And here is my question - how to organise them. When I put all panels in one class it becomes quickly huge and generates many many bugs. It's also hard to find a part of code which is broken. Should every panel be defined in a different class? But if so, there is a problem with returning from submenus to main menu.

Or another example. First panel of program is login page and the next page depends on the inserted login.

How should I organize a lot of panels? Any help would be appreciated :)

Answer 1

If your project is not too big, then i would suggest making a Presenter class, which would control the stage and the program flow and which shows up one of many View classes.

This is an example of a presenter class:

class Presenter {

public void showA(Stage mainStage){
    ViewA a = new ViewA();
    a.setOnBackButton(new ViewCallback(){
        public void call(){
            showB();
        }
    });
    mainStage.setScene(new Scene(a));
}

public void showB(Stage mainStage){
    ViewB b = new ViewB();
    b.setOnBackButton(new ViewCallback(){
        public void call(){
            showA();
        }
    });
    mainStage.setScene(new Scene(b));
}

}

This is example of a view body:

public class ViewA {

private ViewCallBack onBackButton = null;

public void setOnBackButton(ViewCallback callback){ onBackButton = callback; }

public void callBack() { if (onBackButton != null) onBackButton.call(); }

...

// somewhere in your code
Button b = new Button("shoot me!");
b.setOnAction(new EventHandler<ActionEvent>(){
    public void handle(ActionEvent event){
        callBack();
    }
});

}

This is the ViewCallback interface

public Interface ViewCallback {
    public void call();
}

You can use this simple callback interface or Callback<P,R> JavFX generic callback interface.