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How to integrate the model part of a program with FXML-Controller? [duplicate]

I'm new to the GUI world/OO design pattern and I want to use MVC pattern for my GUI application, I have read a little tutorial about MVC pattern, the Model will contain the data, the View will contain the visual element and the Controller will tie between the View and the Model.
I have a View that contains a ListView node, and the ListView will be filled with names, from a Person Class (Model). But I'm a little confused about one thing.
What I want to know is if loading the data from a file is the responsibility of the Controller or the Model?? And the ObservableList of the names: should it be stored in the Controller or the Model?

There are many different variations of this pattern. In particular, "MVC" in the context of a web application is interpreted somewhat differently to "MVC" in the context of a thick client (e.g. desktop) application (because a web application has to sit atop the request-response cycle). This is just one approach to implementing MVC in the context of a thick client application, using JavaFX.
Your Person class is not really the model, unless you have a very simple application: this is typically what we call a domain object, and the model will contain references to it, along with other data. In a narrow context, such as when you are just thinking about the ListView, you can think of the Person as your data model (it models the data in each element of the ListView), but in the wider context of the application, there is more data and state to consider.
If you are displaying a ListView<Person> the data you need, as a minimum, is an ObservableList<Person>. You might also want a property such as currentPerson, that might represent the selected item in the list.
If the only view you have is the ListView, then creating a separate class to store this would be overkill, but any real application will usually end up with multiple views. At this point, having the data shared in a model becomes a very useful way for different controllers to communicate with each other.
So, for example, you might have something like this:
public class DataModel {
private final ObservableList<Person> personList = FXCollections.observableArrayList();
private final ObjectProperty<Person> currentPerson = new SimpleObjectPropery<>(null);
public ObjectProperty<Person> currentPersonProperty() {
return currentPerson ;
}
public final Person getCurrentPerson() {
return currentPerson().get();
}
public final void setCurrentPerson(Person person) {
currentPerson().set(person);
}
public ObservableList<Person> getPersonList() {
return personList ;
}
}
Now you might have a controller for the ListView display that looks like this:
public class ListController {
#FXML
private ListView<Person> listView ;
private DataModel model ;
public void initModel(DataModel model) {
// ensure model is only set once:
if (this.model != null) {
throw new IllegalStateException("Model can only be initialized once");
}
this.model = model ;
listView.setItems(model.getPersonList());
listView.getSelectionModel().selectedItemProperty().addListener((obs, oldSelection, newSelection) ->
model.setCurrentPerson(newSelection));
model.currentPersonProperty().addListener((obs, oldPerson, newPerson) -> {
if (newPerson == null) {
listView.getSelectionModel().clearSelection();
} else {
listView.getSelectionModel().select(newPerson);
}
});
}
}
This controller essentially just binds the data displayed in the list to the data in the model, and ensures the model's currentPerson is always the selected item in the list view.
Now you might have another view, say an editor, with three text fields for the firstName, lastName, and email properties of a person. It's controller might look like:
public class EditorController {
#FXML
private TextField firstNameField ;
#FXML
private TextField lastNameField ;
#FXML
private TextField emailField ;
private DataModel model ;
public void initModel(DataModel model) {
if (this.model != null) {
throw new IllegalStateException("Model can only be initialized once");
}
this.model = model ;
model.currentPersonProperty().addListener((obs, oldPerson, newPerson) -> {
if (oldPerson != null) {
firstNameField.textProperty().unbindBidirectional(oldPerson.firstNameProperty());
lastNameField.textProperty().unbindBidirectional(oldPerson.lastNameProperty());
emailField.textProperty().unbindBidirectional(oldPerson.emailProperty());
}
if (newPerson == null) {
firstNameField.setText("");
lastNameField.setText("");
emailField.setText("");
} else {
firstNameField.textProperty().bindBidirectional(newPerson.firstNameProperty());
lastNameField.textProperty().bindBidirectional(newPerson.lastNameProperty());
emailField.textProperty().bindBidirectional(newPerson.emailProperty());
}
});
}
}
Now if you set things up so both these controllers are sharing the same model, the editor will edit the currently selected item in the list.
Loading and saving data should be done via the model. Sometimes you will even factor this out into a separate class to which the model has a reference (allowing you to easily switch between a file-based data loader and a database data loader, or an implementation that accesses a web service, for example). In the simple case you might do
public class DataModel {
// other code as before...
public void loadData(File file) throws IOException {
// load data from file and store in personList...
}
public void saveData(File file) throws IOException {
// save contents of personList to file ...
}
}
Then you might have a controller that provides access to this functionality:
public class MenuController {
private DataModel model ;
#FXML
private MenuBar menuBar ;
public void initModel(DataModel model) {
if (this.model != null) {
throw new IllegalStateException("Model can only be initialized once");
}
this.model = model ;
}
#FXML
public void load() {
FileChooser chooser = new FileChooser();
File file = chooser.showOpenDialog(menuBar.getScene().getWindow());
if (file != null) {
try {
model.loadData(file);
} catch (IOException exc) {
// handle exception...
}
}
}
#FXML
public void save() {
// similar to load...
}
}
Now you can easily assemble an application:
public class ContactApp extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
BorderPane root = new BorderPane();
FXMLLoader listLoader = new FXMLLoader(getClass().getResource("list.fxml"));
root.setCenter(listLoader.load());
ListController listController = listLoader.getController();
FXMLLoader editorLoader = new FXMLLoader(getClass().getResource("editor.fxml"));
root.setRight(editorLoader.load());
EditorController editorController = editorLoader.getController();
FXMLLoader menuLoader = new FXMLLoader(getClass().getResource("menu.fxml"));
root.setTop(menuLoader.load());
MenuController menuController = menuLoader.getController();
DataModel model = new DataModel();
listController.initModel(model);
editorController.initModel(model);
menuController.initModel(model);
Scene scene = new Scene(root, 800, 600);
primaryStage.setScene(scene);
primaryStage.show();
}
}
As I said, there are many variations of this pattern (and this is probably more a model-view-presenter, or "passive view" variation), but that's one approach (one I basically favor). It's a bit more natural to provide the model to the controllers via their constructor, but then it's a lot harder to define the controller class with a fx:controller attribute. This pattern also lends itself strongly to dependency injection frameworks.
Update: full code for this example is here.
If you are interested in a tutorial on MVC in JavaFX, see:
The Eden Coding tutorial: How to apply MVC in JavaFX

What i want to know is that if loading the data from a file is the responsibility of the Controller Or the model?
For me the model is only responsible of bringing the required data structures that represent the business logic of the application.
The action of loading that data from any source should be done by the Controller Layer. You could also use the repository pattern, which can help you in abstracting from the type of source when you are acessing the data from the view. With this implemented you should not care if the Repository implementation is loading the data from file, SQL, NoSQL, Web service ...
And the ObservableList of the names will be stored in the controller or the model?
For me the ObservableList is part of the View. It is the kind of data structure you can bind to JavaFX controls. So for example a ObservableList<String> could be populated with Strings from the model but the ObservableList reference should be an attribute of some View´s class.
In JavaFX it's very pleasant to bind JavaFX controls with Observable Properties backed by domain objects from the model.
You could also have a look to viewmodel concept. For me a JavaFX bean backed by a POJO could be considered as a view-model, you could see it as a model object ready to be presented in the view. So for example if your view needs to show some total value calculated from 2 model attributes, this total value could be an attribute of the view-model. This attribute would not be persisted and it would be calculated any time you show the view.

delete an item from a listview using a button on the listitem [duplicate]

I'm new to the GUI world/OO design pattern and I want to use MVC pattern for my GUI application, I have read a little tutorial about MVC pattern, the Model will contain the data, the View will contain the visual element and the Controller will tie between the View and the Model.
I have a View that contains a ListView node, and the ListView will be filled with names, from a Person Class (Model). But I'm a little confused about one thing.
What I want to know is if loading the data from a file is the responsibility of the Controller or the Model?? And the ObservableList of the names: should it be stored in the Controller or the Model?

There are many different variations of this pattern. In particular, "MVC" in the context of a web application is interpreted somewhat differently to "MVC" in the context of a thick client (e.g. desktop) application (because a web application has to sit atop the request-response cycle). This is just one approach to implementing MVC in the context of a thick client application, using JavaFX.
Your Person class is not really the model, unless you have a very simple application: this is typically what we call a domain object, and the model will contain references to it, along with other data. In a narrow context, such as when you are just thinking about the ListView, you can think of the Person as your data model (it models the data in each element of the ListView), but in the wider context of the application, there is more data and state to consider.
If you are displaying a ListView<Person> the data you need, as a minimum, is an ObservableList<Person>. You might also want a property such as currentPerson, that might represent the selected item in the list.
If the only view you have is the ListView, then creating a separate class to store this would be overkill, but any real application will usually end up with multiple views. At this point, having the data shared in a model becomes a very useful way for different controllers to communicate with each other.
So, for example, you might have something like this:
public class DataModel {
private final ObservableList<Person> personList = FXCollections.observableArrayList();
private final ObjectProperty<Person> currentPerson = new SimpleObjectPropery<>(null);
public ObjectProperty<Person> currentPersonProperty() {
return currentPerson ;
}
public final Person getCurrentPerson() {
return currentPerson().get();
}
public final void setCurrentPerson(Person person) {
currentPerson().set(person);
}
public ObservableList<Person> getPersonList() {
return personList ;
}
}
Now you might have a controller for the ListView display that looks like this:
public class ListController {
#FXML
private ListView<Person> listView ;
private DataModel model ;
public void initModel(DataModel model) {
// ensure model is only set once:
if (this.model != null) {
throw new IllegalStateException("Model can only be initialized once");
}
this.model = model ;
listView.setItems(model.getPersonList());
listView.getSelectionModel().selectedItemProperty().addListener((obs, oldSelection, newSelection) ->
model.setCurrentPerson(newSelection));
model.currentPersonProperty().addListener((obs, oldPerson, newPerson) -> {
if (newPerson == null) {
listView.getSelectionModel().clearSelection();
} else {
listView.getSelectionModel().select(newPerson);
}
});
}
}
This controller essentially just binds the data displayed in the list to the data in the model, and ensures the model's currentPerson is always the selected item in the list view.
Now you might have another view, say an editor, with three text fields for the firstName, lastName, and email properties of a person. It's controller might look like:
public class EditorController {
#FXML
private TextField firstNameField ;
#FXML
private TextField lastNameField ;
#FXML
private TextField emailField ;
private DataModel model ;
public void initModel(DataModel model) {
if (this.model != null) {
throw new IllegalStateException("Model can only be initialized once");
}
this.model = model ;
model.currentPersonProperty().addListener((obs, oldPerson, newPerson) -> {
if (oldPerson != null) {
firstNameField.textProperty().unbindBidirectional(oldPerson.firstNameProperty());
lastNameField.textProperty().unbindBidirectional(oldPerson.lastNameProperty());
emailField.textProperty().unbindBidirectional(oldPerson.emailProperty());
}
if (newPerson == null) {
firstNameField.setText("");
lastNameField.setText("");
emailField.setText("");
} else {
firstNameField.textProperty().bindBidirectional(newPerson.firstNameProperty());
lastNameField.textProperty().bindBidirectional(newPerson.lastNameProperty());
emailField.textProperty().bindBidirectional(newPerson.emailProperty());
}
});
}
}
Now if you set things up so both these controllers are sharing the same model, the editor will edit the currently selected item in the list.
Loading and saving data should be done via the model. Sometimes you will even factor this out into a separate class to which the model has a reference (allowing you to easily switch between a file-based data loader and a database data loader, or an implementation that accesses a web service, for example). In the simple case you might do
public class DataModel {
// other code as before...
public void loadData(File file) throws IOException {
// load data from file and store in personList...
}
public void saveData(File file) throws IOException {
// save contents of personList to file ...
}
}
Then you might have a controller that provides access to this functionality:
public class MenuController {
private DataModel model ;
#FXML
private MenuBar menuBar ;
public void initModel(DataModel model) {
if (this.model != null) {
throw new IllegalStateException("Model can only be initialized once");
}
this.model = model ;
}
#FXML
public void load() {
FileChooser chooser = new FileChooser();
File file = chooser.showOpenDialog(menuBar.getScene().getWindow());
if (file != null) {
try {
model.loadData(file);
} catch (IOException exc) {
// handle exception...
}
}
}
#FXML
public void save() {
// similar to load...
}
}
Now you can easily assemble an application:
public class ContactApp extends Application {
#Override
public void start(Stage primaryStage) throws Exception {
BorderPane root = new BorderPane();
FXMLLoader listLoader = new FXMLLoader(getClass().getResource("list.fxml"));
root.setCenter(listLoader.load());
ListController listController = listLoader.getController();
FXMLLoader editorLoader = new FXMLLoader(getClass().getResource("editor.fxml"));
root.setRight(editorLoader.load());
EditorController editorController = editorLoader.getController();
FXMLLoader menuLoader = new FXMLLoader(getClass().getResource("menu.fxml"));
root.setTop(menuLoader.load());
MenuController menuController = menuLoader.getController();
DataModel model = new DataModel();
listController.initModel(model);
editorController.initModel(model);
menuController.initModel(model);
Scene scene = new Scene(root, 800, 600);
primaryStage.setScene(scene);
primaryStage.show();
}
}
As I said, there are many variations of this pattern (and this is probably more a model-view-presenter, or "passive view" variation), but that's one approach (one I basically favor). It's a bit more natural to provide the model to the controllers via their constructor, but then it's a lot harder to define the controller class with a fx:controller attribute. This pattern also lends itself strongly to dependency injection frameworks.
Update: full code for this example is here.
If you are interested in a tutorial on MVC in JavaFX, see:
The Eden Coding tutorial: How to apply MVC in JavaFX

What i want to know is that if loading the data from a file is the responsibility of the Controller Or the model?
For me the model is only responsible of bringing the required data structures that represent the business logic of the application.
The action of loading that data from any source should be done by the Controller Layer. You could also use the repository pattern, which can help you in abstracting from the type of source when you are acessing the data from the view. With this implemented you should not care if the Repository implementation is loading the data from file, SQL, NoSQL, Web service ...
And the ObservableList of the names will be stored in the controller or the model?
For me the ObservableList is part of the View. It is the kind of data structure you can bind to JavaFX controls. So for example a ObservableList<String> could be populated with Strings from the model but the ObservableList reference should be an attribute of some View´s class.
In JavaFX it's very pleasant to bind JavaFX controls with Observable Properties backed by domain objects from the model.
You could also have a look to viewmodel concept. For me a JavaFX bean backed by a POJO could be considered as a view-model, you could see it as a model object ready to be presented in the view. So for example if your view needs to show some total value calculated from 2 model attributes, this total value could be an attribute of the view-model. This attribute would not be persisted and it would be calculated any time you show the view.

Display Exact Copy of Stage

I am working on a new project that will need to show a separate stage on the secondary monitor. This will be a non-interactive stage (only used to display nodes). I will follow this approach to handle that part.
However, I also want to have a duplicate copy of that stage visible within a pane in my main app. It would need to update itself at the same time the stage does.
Where would I start learning how to implement this? Does Java provide a built-in API to display realtime screenshots of a stage, by chance?

I am no expert but I think there are two ways to do it.
Method 1
Wrap everything of that stage into a main FXML/controller file/class (as a View). Then you need to load that FXML file twice, once in the new stage, the other in a dedicated space you have prepared in your main stage.
The reference of both controller instances should ideally be held at the same object, either in your application class or the class hosting your main stage.
From there, you can either bind values and let the binding API do the work for you.
Example:
Main View:
public class MainView {
private Model model = new Model();
private Pane space; // Dedicated space
public void spawnView() {
FXMLLoader spawnViewLoader = new FXMLLoader(getClass().getResource("View.fxml"));
Parent spawnView = spawnViewLoader.load(); // Need to catch IOException
ViewController spawnController = spawnViewLoader.getController();
spawnController.setup(model);
new Stage(new Scene(view));
FXMLLoader dupViewLoader = new FXMLLoader(getClass().getResource("View.fxml"));
Parent dupView = dupViewLoader.load(); // Need to catch IOException
ViewController dupController = dupViewLoader.getController();
dupController.setup(model);
space.getChildren().setAll(dupView);
}
}
Model:
public class Model {
private final StringProperty title = new SimpleStringProperty();
private final StringProperty titleProperty() { return title; }
private final String getTitle() { return title.get(); }
private final void setTitle(final String title) { this.title.set(title); }
}
View controller:
public class ViewController {
#FXML private Label label;
private Model model;
public void setup(Model model) {
if (model == null)
throw new NullPointerException();
this.model = model;
label.textProperty().bind(model.titleProperty());
}
// Other stuff
}
Be careful of the binding though - I'm quite sure whatever I wrote is going to cause memory leak; both Views will not clean up as long you're holding a reference of model. You can always do it without binding, but it's going to be more tedious to update values.
Method 2
This method is more complex and is likely to be several frames slower. I'm not going to post sample codes as this is not that straight-forward.
You need to have a reference of the Scene of that stage, and use an AnimationTimer to call the snapshot method of the scene object.
Then you need to use an ImageView in your main stage to display the snapshots returned.
Seriously, I think this method would cause the duplicate View to be several frames slower than the original's.

JavaFX how to inject new FXML content to current Scene

I have an app, which has HomeScene.fxml file with headers and menu. HomeScene has also dashboardPane, which should be changed dynamically after menu button is being pressed. Dashboard pane content should be loaded from another fxml file, lets say 'FinancesPane.fxml' or 'SettingsPane.fxml'.
Im trying to replace content of dashboardPane in HomeController:
#FXML
public void handleFinancesButtonAction() {
FinancesPaneFactory paneFactory = new FinancesPaneFactory();
dashBoardPane.getChildren().clear();
dashBoardPane.getChildren().add(paneFactory.createPane());
}
My FinancesPaneFactory looks like this:
public class FinancesPaneFactory extends PaneFactory {
private static final String PANE_TEMPLATE_PATH = "/sceneTemplates/FinancesPane.fxml";
public FinancesPaneFactory() {
super(PANE_TEMPLATE_PATH );
}
#Override
protected Pane generatePane(FXMLLoader loader) {
try {
return (Pane) loader.load();
} catch (IOException e) {
throw new FatBirdRuntimeException("Unable to load FinancesPane", e);
}
}
}
To be more clear, this is how HomeScene looks like: HomeScene .
This empty space is a dashboardPane, and should be replaced with another content when user press the left menu button.
How to inject this content dynamically?

Yes, you should do this to keep scene graph low and you will benefit from better performance , what i do is create dynamic container :
#FXML
private ScrollPane dynamicNode;
Scroll pane is a good choice.
This is put to MainController.
I have main controller different from others , main controller is actually the only one i initialize, so in your main program class whatever you call it :
private static MainViewController mainViewController;
...
private static BorderPane loadMainPane() throws IOException {
FXMLLoader loader = new FXMLLoader();
loader.setController(mainViewController);
BorderPane mainPane = (BorderPane) loader.load(
CsgoRr.class
.getResourceAsStream(Info.Resource.FXML_FILE_MAIN));
mainPane.getStylesheets().add(CsgoRr.class.getResource("path...style.css").toString());
return mainPane;
}
Dont forget to create static accessor, other controllers that i have are usually not created this way , i use fx:controller in fxml to specify what controller should be for which fxml , its usually handy to have mainController accessable.
So to change your views create in your main controller methods that are connected to your menu with whose you change views
#FXML
private void setViewPreferences() {
setView(Info.Resource.FXML_FILE_PREFERENCES);
}
#FXML
private void setViewProductPage() {
setView(Info.Resource.FXML_FILE_PRODUCT_PAGE);
}
Currently in dynamicNode is helper to see what exactly is the current selected, its
private String currentlyInDynamicPane;//not important
Here is setView
public void setView(String fxmlPath) {
dynamicNode.setContent(getView(fxmlPath));
currentlyInDynamicPane = fxmlPath;
}
public Node getView(String fxmlPath) {
try {
return new FXMLLoader(getClass().getResource(fxmlPath)).load();
} catch (IOException ex) {
ex.printStackTrace();
return null;
}
}
So when you click left menu you swap FXML files, you can make sure that you have some default FXML shown at the start or when nothing in menu is selected as well.
This is the way i do it, roughly.
So think about YOUR DASHBOARD as DynamicPane,

How can I pass objects between the JavaFX controllers in this source code?

Link to tutorial explaining the code.
https://www.youtube.com/watch?v=5GsdaZWDcdY
Overview:
class ScreensController extends StackPane //keep pane so we can remove add screens on top/bottom
It has this method for loading multiple screens.
public boolean loadScreen(String name, String resource) {
try { //fxml file
FXMLLoader myLoader = new FXMLLoader(getClass().getResource(resource));
//System.out.println(resource);
Parent loadScreen = (Parent) myLoader.load();//class cast to controlled screen
ControlledScreen myScreenControler = ((ControlledScreen) myLoader.getController());//Returns the controller associated with the root object.
//inject screen controllers to myscreencontroller
myScreenControler.setScreenParent(this);// inject screen controllers to each screen here
addScreen(name, loadScreen);
return true;
} catch (Exception e) {
System.out.println(e.getMessage());
return false;
}
}
Each screen controller has this object
ScreensController myController;
And this method for switching between screens (switch which controller is in control)
#FXML
private void goToScreen2(ActionEvent event){
myController.setScreen(ScreensFramework.screen2ID);
}
public interface ControlledScreen {
//This method will allow the injection of the Parent ScreenPane
public void setScreenParent(ScreensController screenPage);
}
This is a very brief synopsis and I'm sure I'm leaving out integral parts of the code.
My question is basically How can I send something (anything) from one screen to another?
I'd also like to be able to have a universal model object that all the controllers can access and control.
If you take a look at my code here
You will see I am putting all my model objects into the "initialize" method of each SEPARATE controller.
If any of you can give me some pointers or feedback on my code I would really appreciate it. Thanks.