The updateItem method should not be called by developers, but it is the
best method for developers to override to allow for them to customise the
visuals of the cell. To clarify, developers should never call this method
in their code (they should leave it up to the UI control, such as the
javafx.scene.control.ListView
control) to call this method. However,
the purpose of having the updateItem method is so that developers, when
specifying custom cell factories (again, like the ListView
cell factory
),
the updateItem method can be overridden to allow for complete customisation
of the cell.
It is very important that subclasses of Cell override the updateItem method properly, as failure to do so will lead to issues such as blank cells or cells with unexpected content appearing within them. Here is an example of how to properly override the updateItem method:
protected void updateItem(T item, boolean empty) { super.updateItem(item, empty); if (empty || item == null) { setText(null); setGraphic(null); } else { setText(item.toString()); } }
Note in this code sample two important points:
empty
condition, and if true, we
set the text and graphic properties to null. If we do not do this,
it is almost guaranteed that end users will see graphical artifacts
in cells unexpectedly.
item | The new item for the cell. | |
empty | whether or not this cell represents data from the list. If it is empty, then it does not represent any domain data, but is a cell being used to render an "empty" row. |
Diagram: TreeTableCell