Как инициализировать DataModel в JavaFX

Question

Я создал модель данных на основе класса Email, в качестве параметра которого указан IntegerProperty, четыре StringProperty и Date.Теперь я пытаюсь показать в своем ListView идентификатор и имя отправителя, и для этого я создал этот метод в ListController:

public class ListController {
private ListView<Email> 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 ;
    this.model.loadData(null);
    **listView.setItems(model.getEmailList());**

    listView.getSelectionModel().selectedItemProperty().addListener((obs, oldSelection, newSelection) -> 
        model.setCurrentEmail(newSelection));

    model.currentEmailProperty().addListener((obs, oldPerson, newPerson) -> {
        if (newPerson == null) {
            listView.getSelectionModel().clearSelection();
        } else {
            listView.getSelectionModel().select(newPerson);
        }
    });

    listView.setCellFactory(lv -> new ListCell<Email>() {
        @Override
        public void updateItem(Email person, boolean empty) {
            super.updateItem(person, empty);
            if (empty) {
                setText(null);
            } else {
                setText(person.getID() + " " + person.getMittente());
            }
        }
    });
}

Проблема в том, что я получаю java.lang.NullPointerException при вызове этого метода: listView.setItems (model.getEmailList ());

Это мой класс DataModel:

public class DataModel {

private final ObservableList<Email> emailList = FXCollections.observableArrayList(email -> 
    new Observable[] {email.IDProperty(), email.MittenteProperty()});

private final ObjectProperty<Email> currentEmail = new SimpleObjectProperty<>(null);

public ObjectProperty<Email> currentEmailProperty() {
    return currentEmail ;
}

public final Email getCurrentEmail() {
    return currentEmailProperty().get();
}

public final void setCurrentEmail(Email email) {
    currentEmailProperty().set(email);
}

public ObservableList<Email> getEmailList() {
    return emailList ;
}

public void loadData(File file) {
    // mock...
    emailList.setAll(
            new Email(1, "Smith", "John", "Casa", "BLAAAAAAAAAAAAA", new Date(1997, 3, 2)),
            new Email(2, "Isabella", "Johnson","Bua", "BUUUUUUU", new Date(1995, 6, 2)), 
            new Email(3, "Ethan", "Williams", "Rapporto", "IIIIIIIIII", new Date(2011, 9, 8)), 
            new Email(4, "Emma", "Jones", "Chiesa", "ALEEEEEEEEEE", new Date(2000, 1, 4)), 
            new Email(5, "Pippo", "Brown", "Vignetta", "OSAAAAAAAA", new Date(1987, 4, 5))
    );
}

public void saveData(File file) { }

}

Как я могузаполнить список, как только я открою программу, не делая этого таким образом?Я получаю NullPointerExcpetion, даже если я заполняю его, вызывая метод loadData.

EDIT: Это основной класс:

public class MailBox extends Application {

@Override
public void start(Stage stage) throws Exception {
    BorderPane root = new BorderPane();

    FXMLLoader listLoader = new FXMLLoader(getClass().getResource("lista.fxml"));
    root.setCenter(listLoader.load());
    ListController listController = listLoader.getController();

    FXMLLoader textareaLoader = new FXMLLoader(getClass().getResource("textarea.fxml"));
    root.setBottom(textareaLoader.load());
    TextAreaController textareaController = textareaLoader.getController();

    DataModel model = new DataModel();
    listController.initModel(model);
    textareaController.initModel(model);

    Scene scene = new Scene(root, 355, 402);
    stage.setScene(scene);
    stage.show();
}

EDIT2: И это класс TextAreaController:

public class TextAreaController {

private DataModel model;
private TextArea textarea;

public void initModel(DataModel model) {
    if (this.model != null) {
        throw new IllegalStateException("Model can only be initialized once");
    }
    this.model = model ;
    model.loadData(null);//  aggiunto per far caricare i dati delle person
    model.currentEmailProperty().addListener((obs, oldEmail, newEmail) -> {
        if (oldEmail != null) {
            String id = "ID: "+Integer.toString(oldEmail.IDProperty().getValue().intValue())+"\n";
            textarea.setText(id);
            /*firstNameField.textProperty().unbindBidirectional(oldEmail.firstNameProperty());
            lastNameField.textProperty().unbindBidirectional(oldEmail.lastNameProperty());
            emailField.textProperty().unbindBidirectional(oldEmail.emailProperty());*/
        }
        if (newEmail == null) {
            textarea.setText("");
            /*firstNameField.setText("");
            lastNameField.setText("");
            emailField.setText("");*/
        } else {
            String id = "ID: "+Integer.toString(newEmail.IDProperty().getValue().intValue())+"\n";
            textarea.setText(id);
            /*firstNameField.textProperty().bindBidirectional(newEmail.firstNameProperty());
            lastNameField.textProperty().bindBidirectional(newEmail.lastNameProperty());
            emailField.textProperty().bindBidirectional(newEmail.emailProperty());*/
        }
    });
}

}

Answer 1

Контроллер:

public class Controller {
    @FXML
    private ListView<Email> listView;
    private DataModel model = new DataModel();

    @FXML
    private void initialize() {
         List<Email> emailList = model.loadData();
         listView.getItems().addAll(emailList);
    }
}

Модель:

public class Email {
    int id;
    String firstProperty;
    String secondProperty;
    String thirdProperty;
    String fourthProperty;
    Date date;

    public Email(int id, String firstProperty, String secondProperty, String thirdProperty, String fourthProperty, Date date) {
         this.id = id;
         this.firstProperty = firstProperty;
         this.secondProperty = secondProperty;
         this.thirdProperty = thirdProperty;
         this.fourthProperty = fourthProperty;
         this.date = date;
    }

    @Override
    public String toString(){
        return ("ID: " + this.id + ", Name: " + this.firstProperty);
    }
}

DataModel:

public class DataModel {
    public List<Email> loadData() {

        List<Email> emailList = new ArrayList<>();

        emailList.addAll(
                Arrays.asList(
                        new Email(1, "Smith", "John", "Casa", "BLAAAAAAAAAAAAA", new Date(1997, 3, 2)),
                        new Email(2, "Isabella", "Johnson", "Bua", "BUUUUUUU", new Date(1995, 6, 2)),
                        new Email(3, "Ethan", "Williams", "Rapporto", "IIIIIIIIII", new Date(2011, 9, 8)),
                        new Email(4, "Emma", "Jones", "Chiesa", "ALEEEEEEEEEE", new Date(2000, 1, 4)),
                        new Email(5, "Pippo", "Brown", "Vignetta", "OSAAAAAAAA", new Date(1987, 4, 5))
                )
        );

        return emailList;
    }
}

Надеюсь, это сработает.