JavaFX custom cell factory with custom Objects
All custom cell implementations that override updateItem(...)
need to deal with the case where the cell is empty in that method. So you could do a naïve fix of this with
public final class ConversationCell<Message> extends ListCell<Message> {
@Override
protected void updateItem(Message item, boolean empty) {
super.updateItem(item, empty);
if (empty) {
setGraphic(null);
} else {
// did you mean to pass null here, or item??
ConversationCellController ccc = new ConversationCellController(null);
setGraphic(ccc.getView());
}
}
}
However, this is not a good solution from the point of view of performance. You are loading the FXML every time updateItem(...)
is called with a non-empty cell, and that's a pretty expensive operation (potentially involving file i/o, unzipping the FXML file from a jar file, parsing the file, lots of reflection, creating new UI elements, etc). You don't want to be asking the FX Application Thread to be doing all that work every time the user scrolls the list view by a few pixels. Instead, your cell should cache the node and should update it in the updateItem
method:
public final class ConversationCell<Message> extends ListCell<Message> {
private final ConversationCellController ccc = new ConversationCellController(null);
private final Node view = ccc.getView();
@Override
protected void updateItem(Message item, boolean empty) {
super.updateItem(item, empty);
if (empty) {
setGraphic(null);
} else {
ccc.setItem(item);
setGraphic(view);
}
}
}
You should define a setItem(...)
method in the ConversationCellController
that updates the view (sets text on labels, etc etc) accordingly.