TableView modify style per cell only [duplicate] - javafx

Question

This question already has an answer here:
How to get row value inside updateItem() of CellFactory
(1 answer)
Closed 4 years ago.
Assume a:
TableView<ResultType, String> table = new TableView<> ();
table.setItems(myItems);
In TableColumn we have the setCellValueFactory method which very nicely gives you access to the ResultType object of the respective cell value. So you can use it to extract the values like that:
aColumnFromTableView.setCellValueFactory(data -> new SimpleStringProperty(data.getValue));
Now each cell from aColumnFromTableView will be populated with a value from all ResultType objects which are set as items for the table.
The question is: can we also change the cell's style in a similar way? I had a look at the setCellFactory method, but it does not seem as friendly as setCellValueFactory though (= it does not provide me the respective ResultType).
Here's what you can do with setCellFactory:
aColumnFromTableView.setCellValueFactory(data -> ???? ); // data is actually aColumnFromTableView itself??
So I am wondering of a way to set the cell style individually similar to what I described with "setCellValueFactory". I hope it exists.
Note: I also tried
aColumnFromTableView.setCellValueFactory(data -> {
aColumnFromTableView.setStyle("my style");
return new SimpleStringProperty(data.getValue);
})
But that sets it for the entire column and not individually.
Thanks!!!!

Answer 1

If you want to customize the style of the TableCell based on the value of the cell you'll need to use a cellFactory and return your own TableCell.
For instance, if you wanted a TableCell<?, Double> that displayed the number in red if it was negative you could do:
column.setCellFactory(col -> new TableCell<>() {
#Override
protected void updateItem(Double item, boolean empty) {
super.updateItem(item, empty);
if (empty || item == null) {
setText(null);
setGraphic(null);
} else {
setText(item.toString());
if (item < 0.0) {
setTextFill(Color.RED); // or use setStyle(String)
} else {
setTextFill(Color.BLACK); // or use setStyle(String)
}
}
}
});
When creating a custom TableCell you'll more than likely want to override the updateItem(Object,boolean) method. It's important you override it correctly, however, if you want it to work right. Read the javadoc for information:
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 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:
We call the super.updateItem(T, boolean) method. If this is not done, the item and empty properties are not correctly set, and you are likely to end up with graphical issues.
We test for the 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.
Instead of setting properties or calling setStyle you could use things like PseudoClass states to make it easier to style from an external CSS stylesheet.
import javafx.css.PseudoClass;
import javafx.scene.control.TableCell;
public class CustomCell<S> extends TableCell<S, Double> {
private static final PseudoClass POSITIVE = PseudoClass.getPseudoClass("positive");
private static final PseudoClass NEGATIVE = PseudoClass.getPseudoClass("negative");
public CustomCell() {
getStyleClass().add("custom-cell");
}
#Override
protected void updateItem(Double item, boolean empty) {
super.updateItem(item, empty);
if (empty || item == null) {
setText(null);
setGraphic(null);
pseudoClassStateChanged(POSITIVE, false);
pseudoClassStateChanged(NEGATIVE, false);
} else {
setText(item.toString()); // you might want to format the number for display
pseudoClassStateChanged(POSITIVE, item >= 0.0);
pseudoClassStateChanged(NEGATIVE, item < 0.0);
}
}
}
Then use:
column.setCellFactory(col -> new CustomCell<>());
And in a stylesheet:
.custom-cell:positive {
-fx-text-fill: black;
}
.custom-cell:negative {
-fx-text-fill: red;
}