Documentation of Cell API says:
Because by far the most common use case for cells is to show text to a user, this use case is specially optimized for within Cell. This is done by Cell extending from Labeled. This means that subclasses of Cell need only set the text property, rather than create a separate Label and set that within the Cell. ...
The current source code of Cell constructor sets the text to null:
public Cell() {
setText(null);
...
}
The subclass IndexedCell
and sub-subclass TableCell
, both of them don't set the text of Labeled
.
The text is set by default cell factory of TableColumn
in source code.
public static final Callback<TableColumn<?,?>, TableCell<?,?>> DEFAULT_CELL_FACTORY = new Callback<TableColumn<?,?>, TableCell<?,?>>() {
@Override public TableCell<?,?> call(TableColumn<?,?> param) {
return new TableCell() {
@Override protected void updateItem(Object item, boolean empty) {
if (item == getItem()) return;
super.updateItem(item, empty);
if (item == null) {
super.setText(null);
super.setGraphic(null);
} else if (item instanceof Node) {
super.setText(null);
super.setGraphic((Node)item);
} else {
super.setText(item.toString());
super.setGraphic(null);
}
}
};
}
};
However by defining your own cell factory that creates new TableCell
but does not set the text in its overriden updateItem()
method, will be resulting an empty (=null) column cell text. So yes the reason of the problem was removing updateItem
method, which calls setText(...)
internally.
EDIT:
Specify the generic types explicitly for TableColumns as,
TableColumn<LiveStock, Integer> idNumber = new TableColumn<LiveStock, Integer>("ID No");
This will avoid type mismatches or wrong type castings.
Then the cell factory callback for your use case will be
Callback<TableColumn<LiveStock, Integer>, TableCell<LiveStock, Integer>> cellFactory =
new Callback<TableColumn<LiveStock, Integer>, TableCell<LiveStock, Integer>>() {
public TableCell<LiveStock, Integer> call(TableColumn<LiveStock, Integer> p) {
TableCell<LiveStock, Integer> cell = new TableCell<LiveStock, Integer>() {
@Override
public void updateItem(Integer item, boolean empty) {
super.updateItem(item, empty);
setText((item == null || empty) ? null : item.toString());
setGraphic(null);
}
};
cell.addEventFilter(MouseEvent.MOUSE_CLICKED, new EventHandler<MouseEvent>() {
@Override
public void handle(MouseEvent event) {
if (event.getClickCount() > 1) {
System.out.println("double clicked!");
TableCell c = (TableCell) event.getSource();
System.out.println("Cell text: " + c.getText());
}
}
});
return cell;
}
};
What is changed?
The type of idNumber in LiveStock is int
. By defining new TableColumn<LiveStock, Integer>
we say this is a column from LiveStock row for its attribute idNumber which has a type int, but the generic types must be a reference type, it cannot be TableCell<LiveStock, int>
so we define TableCell<LiveStock, Integer>
. The thumb of rule: row item class's attribute type should match the second generic type parameter of TableColumn and due to this the parameter of TableCell also.
getString method is defined in the referenced answer link mentioned by you. But it is just a user defined method, not mandatory to use it.