[FIXED] How to avoid closing popup menu on mouse clicking in javafx combobox?

Issue

I have combobox with custom ListCell:

private class SeverityCell extends ListCell<CustomItem> {
    private final CustomBox custombox;

    {
        setContentDisplay(ContentDisplay.GRAPHIC_ONLY); 
        custombox = new CustomBox();
    }

    @Override 
    protected void updateItem(CustomItem item, boolean empty) {         
        super.updateItem(item, empty);
        if (null != item) {
            //...
        }
        setGraphic(custombox);
    }
}

and

combobox.setCellFactory(new Callback<ListView<CustomItem>, ListCell<CustomItem>>() {
    @Override public ListCell<CustomItem> call(ListView<CustomItem> p) {
        return new SeverityCell();
    }
});

When I click on mu custom component popup closes, but I want to avoid it. Which method/event I need to override?

Solution

ComboBox internally utilizes ListView for rendering its items. Also its skin class is ComboBoxListViewSkin. In a source code of this class there is boolean flag to control popup hiding behavior:

// Added to allow subclasses to prevent the popup from hiding when the
// ListView is clicked on (e.g when the list cells have checkboxes).
protected boolean isHideOnClickEnabled() {
    return true;
}

which is used on listview:

       _listView.addEventFilter(MouseEvent.MOUSE_RELEASED, t -> {
            // RT-18672: Without checking if the user is clicking in the
            // scrollbar area of the ListView, the comboBox will hide. Therefore,
            // we add the check below to prevent this from happening.
            EventTarget target = t.getTarget();
            if (target instanceof Parent) {
                List<String> s = ((Parent) target).getStyleClass();
                if (s.contains("thumb")
                        || s.contains("track")
                        || s.contains("decrement-arrow")
                        || s.contains("increment-arrow")) {
                    return;
                }
            }

            if (isHideOnClickEnabled()) {
                comboBox.hide();
            }
        });

So the behavior you want can be (and probably should be) implemented with custom skin. However, the workaround can be

combobox.setSkin( new ComboBoxListViewSkin<CustomItem>( combobox )
{
    @Override
    protected boolean isHideOnClickEnabled()
    {
        return false;
    }
} );

and manually hide the popup, when the value is changed for instance:

combobox.valueProperty().addListener( new ChangeListener()
{
    @Override
    public void changed( ObservableValue observable, Object oldValue, Object newValue )
    {
        combobox.hide();
    }
});

Note please, I didn't fully test this anonymous inner skin approach.

Answered By - Uluk Biy