Wermerb Wermerb - 1 month ago 18
Java Question

ListView using custom cell factory doesn't update after items deleted

I'm learning JavaFX and i wanted to create a cell factory which is working properly until i want to delete a row from my

ListView
:

plateList.setCellFactory(new Callback<ListView<Car>, ListCell<Car>>() {

@Override
public ListCell<Car> call(ListView<Car> param) {
ListCell<Car> cell = new ListCell<Car>() {

@Override
protected void updateItem(Car item, boolean empty) {
super.updateItem(item, empty);
if (item != null) {
setText(item.getPlate());
}
}
};
return cell;
}
});


I'm populating the
ListView
with some sample data:

ObservableList<Car> sample = FXCollections.observableArrayList();
sample.add(new Car("123-abc", "opel", "corsa", 5.5));
sample.add(new Car("123-cba", "vw", "passat", 7.5));
plateList.setItems(sample);


Now i will see what i expect the
ListView
will be the following:


  • 123-abc

  • 123-cba



How ever if delete a row ex: the first row (123-abc), the
ListView
will look like this:


  • 123-cba

  • 123-cba



This is the delete part:

@FXML
private void deleteBtnAction() {
plateList.getItems().remove(plateList.getSelectionModel().getSelectedItem());
ObservableList<Car> t = plateList.getItems();
plateList.setItems(t);

}


If i remove the cell factory the program works as intended.
Any help is greatly appreciated.

Answer

Try changing to the following, This is required as JavaFX reuses the list cells, so the updateItem() needs to blank unused ones too when passed null

super.updateItem(item, empty);
if (item != null) {
   setText(item.getPlate());
} else {
   setText("");   // <== clear the now empty cell.
}

Full SSCCE

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Callback;

public class JavaFxListView extends Application {

    private static class Car {
        private String plate;

        public Car(String plate, String string2, String string3, double d) {
            this.plate = plate;
        }

        public String getPlate() {
            return plate;
        }

    }

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage arg0) throws Exception {
        ListView<Car> plateList = new ListView<Car>();
        plateList.setCellFactory(new Callback<ListView<Car>, ListCell<Car>>() {

            @Override
            public ListCell<Car> call(ListView<Car> param) {
                ListCell<Car> cell = new ListCell<Car>() {

                    @Override
                    protected void updateItem(Car item, boolean empty) {
                        super.updateItem(item, empty);
                        if (item != null) {
                            setText(item.getPlate());
                        } else {
                            setText("");
                        }
                    }
                };
                return cell;
            }
        });
        Button delete = new Button("Delete");
        ObservableList<Car> sample = FXCollections.observableArrayList();
        sample.add(new Car("123-abc", "opel", "corsa", 5.5));
        sample.add(new Car("123-cba", "vw", "passat", 7.5));

        delete.setOnAction((e) -> {
            plateList.getItems().remove(plateList.getSelectionModel().getSelectedItem());
            ObservableList<Car> t = plateList.getItems();
            plateList.setItems(t);
        });

        plateList.setItems(sample);
        arg0.setScene(new Scene(new VBox(plateList, delete)));
        arg0.show();
    }
}
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