如何在JavaFX中动态更新ListView单元？

Question

I have a large OvervableList<Website> that is obtained from calling mainApp.getWebsitData() .

In this controller, I make 3 separate FilteredList<Websites> : keepData , deleteData and newData based on 2 boolean properties of Website :

private final BooleanProperty keep;
private final BooleanProperty delete;

Those 3 filtered lists are displayed in 3 different ListView s.

I have buttons next to each item in the newData list where I make either keep or delete true. Doing so should move that website object to either the keep list or delete list. However, when I click the button the list views are not updating appropriately.

public class WebsiteOverviewController {


    @FXML
    private ListView<Website> deleteList;

    @FXML 
    private ListView<Website> keepList;

    @FXML
    private ListView<Website> newList;

    @FXML
    private JFXButton scanButton;

    @FXML
    private JFXButton pauseButton;

    @FXML
    private StackPane stackPane;

    private BooleanProperty isScanning = new SimpleBooleanProperty(false);

    private MainApp mainApp;

    private FilteredList<Website> keepData;

    private FilteredList<Website> deleteData;

    private FilteredList<Website> newData;

    private AtomicBoolean paused = new AtomicBoolean(false);

    private Thread thread;

    public WebsiteOverviewController() {

    }

    @FXML
    public void initialize() {
        scanButton.setContentDisplay(ContentDisplay.RIGHT);
    }

    public void setMainApp(MainApp mainApp) {
        this.mainApp = mainApp;

        keepData = new FilteredList<>(mainApp.getWebsiteData(), p -> (!p.getDelete() && p.getKeep()));
        deleteData = new FilteredList<>(mainApp.getWebsiteData(), p -> (p.getDelete() && !p.getKeep()));

        newData = new FilteredList<>(mainApp.getWebsiteData(), p -> (!p.getKeep() && !p.getDelete()));

        if (!deleteData.isEmpty()) {
            deleteList.setItems(deleteData);

            deleteList.setCellFactory(param -> new ListCell<Website>() {
                @Override
                protected void updateItem(Website item, boolean empty) {
                    super.updateItem(item,  empty);

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

        if (!keepData.isEmpty()) {
            keepList.setItems(keepData);

            keepList.setCellFactory(param -> new ListCell<Website>() {
                @Override
                protected void updateItem(Website item, boolean empty) {
                    super.updateItem(item,  empty);

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

        if (!newData.isEmpty()) {
            newList.setItems(newData);

            newList.setCellFactory(param -> new ListCell<Website>() {
                @Override
                protected void updateItem(Website item, boolean empty) {
                    super.updateItem(item, empty);

                    if (empty || item == null) {
                        setText(null);
                    } else {
                        HBox hBox = new HBox();
                        hBox.setAlignment(Pos.CENTER);
                        JFXButton keepBtn = new JFXButton("Keep");
                        JFXButton deleteBtn = new JFXButton("Delete");

                        Label label = new Label(item.getWebsite());
                        label.setAlignment(Pos.CENTER);

                        hBox.getChildren().addAll(keepBtn, label, deleteBtn);
                        setGraphic(hBox);

                        keepBtn.setOnAction(new EventHandler<ActionEvent>() {
                            @Override
                            public void handle(ActionEvent event) {
                                System.out.println(item.getWebsite());
                                item.setKeep(true);
                            }
                        });
                    }
                }
            });
        }
        scanButton.visibleProperty().bind(isScanning.not());
        pauseButton.visibleProperty().bind(isScanning);


    }

    @FXML
    public void handleScanInbox() {
        isScanning.set(true);

        if (thread == null) {
            thread = new Thread() {
                public void run() {
                    mainApp.handleScanInbox(paused);
                }
            };
            thread.setDaemon(true);
            thread.start();
        } else {
            synchronized (paused) {
                if (paused.get()) {
                    paused.set(false);
                    paused.notify();
                }
            }
        }

    }

    @FXML
    public void handlePauseScanInbox() {
        paused.compareAndSet(false,  true);
        isScanning.set(false);

    }



}

Any ideas on how to update the lists dynamically?

Answer 1

For the FilteredList to be updated, the listener added to the ObservableList needs to be triggered. Modifying a property of a list element won't do the trick by default.

If you create the list using a extractor for element properties that should trigger update changes, the FilteredList updates too.

Example

public class Item {
    private final int i;
    private final BooleanProperty keep = new SimpleBooleanProperty();

    public Item(int i) {
        this.i = i;
    }

    @Override
    public String toString() {
        return Integer.toString(i);
    }

    public BooleanProperty keepProperty() {
        return keep;
    }

    public boolean isKeep() {
        return keep.get();
    }

    public void setKeep(boolean value) {
        keep.set(value);
    }

}

ObservableList<Item> data = FXCollections.observableArrayList(new Callback<Item, Observable[]>() {

    @Override
    public Observable[] call(Item param) {
        return new Observable[] { param.keepProperty() };
    }

});
for (int i = 0; i < 10; i++) {
    data.add(new Item(i));
}
FilteredList<Item> filtered = new FilteredList<>(data, Item::isKeep);
filtered.addListener((Observable o) -> System.out.println(filtered));
data.get(3).setKeep(true);
data.get(6).setKeep(true);
data.get(7).setKeep(true);
data.get(3).setKeep(false);

Output

[3]
[3, 6]
[3, 6, 7]
[6, 7]

---

Returning an array containing multiple Observable s triggers an update, if any of those Observable s is modified.

I recommend double checking, if keep and delete are actually properties associated with the item type or if you simply added those properties to be able to partition your list into 3 FilteredList s. Would a database table containing the item contain columns for those values? Would you save them to a output file, if you had to save the items to a file?
If the answer to these questions is "No" , you should use 3 seperate ObservableList s. Moving items from one list to another is less complicated than dealing with 2 properties and filtering the list based on those.

Answer 2

Why you use a BooleanProperty for this, is there any reason? Because you can just go with 3 List.

You can go with 2 Options, you can make a Context Menu for the List View or a Button next to it, i am a fan of the Context Menu.

In FXML you can specify a setOnAction()-Method, this method can be used to transfer the Selection Model from one Node to one of your keep or delete Lists.

After this everything should work fine.

private ListView<String>list;
private ListView<String> deleteList;

@FXML
private final void deleteSetOnAction(ActionEvent event) {
    deleteList.getItems().addAll(list.getSelectionModel().getSelectedItems());
    list.getItems().removeAll(list.getSelectionModel().getSelectedItems());
}

The deleteSetOnActionMethod is specified for a button or Context Menu in this example.