JavaFX Changing cell to icon - javafx

Question

I have an issue with changing cell to an icon with the following code:
TableColumn typeCol = new TableColumn("Account Type");
typeCol.setCellFactory(new Callback<TableColumn<Account, String>, TableCell<Account, String>>() {
#Override
public TableCell<Account, String> call(TableColumn<Account, String> param) {
TableCell<Account,String> cell = new TableCell<Account, String>(){
#Override
public void updateItem(Account item, boolean empty){
if (item != null){
VBox vb = new VBox();
vb.setAlignment(Pos.CENTER);
ImageView imgVw = new ImageView(item.getTypeIcon());
imgVw.setFitHeight(10);
imgVw.setFitWidth(10);
vb.getChildren().addAll(imgVw);
setGraphic(vb);
}
}
};
return cell;
}
});
typeCol.setMinWidth(100);
typeCol.setCellValueFactory(
new PropertyValueFactory<Account, String>("type"));
The issue here is that for some reason I get en error of 'method does not override or implement a method form a supertype'. Any idaes?

Answer 1

TableCell<S, T> extends Cell<T>, not Cell<S>. Therefore the correct signature for the updateItem method of TableCell<Account, String> is
public void updateItem(String item, boolean empty)
Assuming your cellValueFactory
new PropertyValueFactory<Account, String>("type")
returns ObservableValues containing the URLs of images, you can use
ImageView imgVw = new ImageView(item);
instead of
ImageView imgVw = new ImageView(item.getTypeIcon());
Since the value passed to the updateItem method is the one that is contained in the ObservableValue returned by the cellValueFactory.

Answer 2

Sample code for placing an image in a table cell:
import javafx.scene.control.*;
import javafx.scene.image.*;
public class ImageTableCell<S> extends TableCell<S, Image> {
private final ImageView imageView = new ImageView();
public ImageTableCell() {
setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
}
#Override
protected void updateItem(Image item, boolean empty) {
super.updateItem(item, empty);
if (empty || item == null) {
imageView.setImage(null);
setText(null);
setGraphic(null);
}
imageView.setImage(item);
setGraphic(imageView);
}
}
This will work fine if your table doesn't represent millions of items. If you have many items and can't hold all of the potential images in memory, then you would need a TableCell instead of TableCell where the string is just the URL of the image rather than the actual image data itself. Then you would keep an LRU cache of image data which you would update in the updateItem, fetching the image data from the cache if it was there, otherwise loading it from the url. Such an approach could get a little tricky as you would probably want to be careful not to do too much dynamic loading of images as the user scrolls. In general, if you just have a few hundred or thousand thumbnail images, then the straight-forward approach defined in the code above would suffice rather than the alternate cache based approach.