Another role of Cell Factory is creating custom cells for your list with any content, instead of text.

In the following setCellFactory method, we will add a color rectangle corresponding to the list-item name:

ObservableList<String> items = FXCollections.observableArrayList(
        "Red", "Blue", "Yellow", "Green");
ListView<String> list = new ListView<>(items);

list.setCellFactory((ListView<String> param) -> {
    return new ListCell<>() {
        @Override
        public void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);
            if (! (empty || item == null)) {
                // adding new item
                setGraphic(new Rectangle(30, 30, Color.web(item)));
                setText(item);
            } else {
                setText(null);
                setGraphic(null);
            }
        }
    };
});

There are quite a few plumbing code lines here, but the main line is the setGraphic() call. It creates an extra graphic element in the list cell:

The setGraphic() method is an entry point to the custom ListView (and other controls with a similar API). You can put anything there; for example, the specialized ListCell classes from the previous sections were implemented using this approach.