[FIXED] JavaFX MenuItem does not react on MouseEvent.CLICKED

Issue

I am writting a little desktop application with a TreeView according to the Oracle-Example from here: https://docs.oracle.com/javafx/2/ui_controls/tree-view.htm.

From a MenuItem action of a ContextMenu, I would like to fire an event which shall create a new TreeItem below the item where I opened the ContextMenu from.

For MenuItem, it is possible to use the setOnAction(EventHandler<ActionEvent> event) method, but I only want to fire the action from a left mouse-click.

First, it is not possible to add an EventHandler to a MenuItem although it provides the method addEventHandler(EventType type, EventHandler<EventType> handler) with the event-type MouseEvent.ANY (or anything else). The handle-method of the event-handler is not called.

Second, i can use a workarround by adding a Label to a MenuItem by menuItem.setGraphic(label) and add an EventHandler to the label. This one works although MouseEvent.MOUSE_CLICKED is not called by an EventHandler's handle-method on a Label.

Is this "normal" behaviour? I understand that a label does not react on a click-event, but I do not understand why it is not possible to register a separate EventHandler or EventFilter on a MenuItem.

Solution

ContextMenu uses a MenuItemContainer, which is a

Container responsible for laying out a single row in the menu - in other words, this contains and lays out a single MenuItem, regardless of it's specific subtype.

Fur this purpose it seems to create new Nodes representing the MenuItem. So any EventHandlers added to the MenuItem will not be called.

To make it work as you intended, you can use a CustomMenuItem and add the according EventHandler to its content:

 public class ContextMenuCell extends TreeCell<String> {

        private ContextMenu menu;

        public ContextMenuCell() {
            Label lbl = new Label("Add item");
            MenuItem menuItem = new CustomMenuItem(lbl);

            lbl.setOnMouseClicked(evt -> {
                if (evt.getButton() != MouseButton.PRIMARY) {
                    return;
                }

                TreeItem treeItem =
                        new TreeItem<String>("New item");

                if (getTreeItem().isLeaf()) {
                    getTreeItem().getParent().getChildren().add(getIndex(), treeItem);
                } else {
                    getTreeItem().getChildren().add(0, treeItem);
                }

            });

            menu = new ContextMenu(menuItem);
        }

        @Override
        public void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);

            if (empty) {
                setText(null);
                setGraphic(null);
            } else {
                setText(item);
                setGraphic(getTreeItem().getGraphic());
                setContextMenu(menu);
            }
        }
    }

Answered By - jns
Answer Checked By - Mary Flores (JavaFixing Volunteer)