使用自定义单元格工厂的ListView在删除项目后不会更新

Question

我正在学习JavaFX,我想创建一个正常工作的单元工厂,直到我想删除我的一行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;
        }
    });

我正在填充ListView一些示例数据:

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);

现在我将看到我期望的ListView将是以下内容:

• 123-ABC
• 123-CBA

如果删除行ex:第一行(123-abc),ListView将如下所示:

• 123-CBA
• 123-CBA

这是删除部分:

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

}

如果我删除了单元工厂,程序按预期工作.任何帮助是极大的赞赏.

Answer 1

尝试更改为以下内容,这是必需的,因为JavaFX重用了列表单元格,因此updateItem()在传递null时也需要清空未使用的列表单元格

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

完整的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();
    }
}

Answer 2

根据Cell updateItem方法的 Java 文档，推荐用法与接受的用法略有不同：

protected void updateItem(T item, boolean empty) {
    super.updateItem(item, empty);

    if (empty || item == null) {
        setText(null);
        setGraphic(null);
    } else {
        setText(item.toString());
    }
}

区别在于参数的使用empty。但@Adam 的解决方案在主要情况下也应该可以正常工作。