自定义表格单元commitEdit（）无法正常工作

Question

我非常接近完成这个TableCell。更新：已经过了updateItem（）块。我忘了事先调用super.updateItem（）。

/**
 * A custom DateTimePicker that lets a user select a LocalDateTime.
 *
 * @author Toni-Tran
 */
public class DateTimePicker extends VBox {

    @FXML
    private DatePicker datePicker;
    @FXML
    private TimePicker timePicker;

    private ObjectProperty<LocalDateTime> value = new SimpleObjectProperty<>();
    private ObjectProperty<EventHandler<ActionEvent>> onAction = new SimpleObjectProperty<>();
    //Why not just use a SimpleObjectProperty? Why extend the base?
//    private ObjectProperty<EventHandler<ActionEvent>> onAction = new ObjectPropertyBase<EventHandler<ActionEvent>>() {
//
//        @Override
//        protected void invalidated() {
//            super.invalidated();
//            setEventHandler(ActionEvent.ACTION, get());
//        }
//
//
//
//        @Override
//        public Object getBean() {
//            return this;
//        }
//
//
//
//        @Override
//        public String getName() {
//            return "onAction";
//        }
//    };



    public DateTimePicker() {
        FXMLLoader loader = new FXMLLoader(this.getClass().getResource(
                ScreenPaths.DATE_TIME_PICKER));
        loader.setController(this);
        loader.setRoot(this);
        try {
            loader.load();
        } catch (IOException e) {
        }
    }



    public DateTimePicker(LocalDateTime ldt) {
        super();
        value.setValue(ldt);
    }



    @FXML
    private void initialize() {
        datePicker.setOnAction(event -> {
            value.setValue(LocalDateTime.of(datePicker.getValue(), timePicker.getValue()));
        });
        value.addListener((ObservableValue<? extends LocalDateTime> observable, LocalDateTime oldValue, LocalDateTime newValue) -> {
            fireEvent(new ActionEvent());
        });
    }



    /**
     * Manually set a LocalDateTime value for this control.
     *
     * @param val The {@link LocalDateTime} value for this control.
     */
    public void setValue(LocalDateTime val) {
        if (val == null) {
            return;
        }
        datePicker.setValue(val.toLocalDate());
        timePicker.setValue(val.toLocalTime());
    }



    /**
     * Returns the currently set LocalDateTime.
     *
     * @return the {@link LocalDateTime} value of this control.
     */
    public LocalDateTime getValue() {
        return value.getValue();
    }



    /**
     * Returns the Observable property of the DateTimePicker's current
     * LocalDateTime value.
     *
     * @return the Observable property of the DateTimePicker's current
     * LocalDateTime value.
     */
    public ObjectProperty<LocalDateTime> valueProperty() {
        return value;
    }



    public final ObjectProperty<EventHandler<ActionEvent>> onActionProperty() {
        return onAction;
    }



    public final EventHandler<ActionEvent> getOnAction() {
        return onActionProperty().get();
    }



    public final void setOnAction(EventHandler<ActionEvent> value) {
        onActionProperty().set(value);
    }
}

但问题是，当调用super.commitEdit（）时，检索的项是null？我认为问题出在我的DateTimePicker类中。在更改的值上，它返回null而不是新值。