java JavaFX我的文件保存不起作用

Question

我有这个购物篮，看这里https://i.stack.imgur.com/9ty3E.png

除了我的文件保存之外，一切都正常。当你保存文件，打开一个现有的项目，它会覆盖旧的xml文件，但它会完全跳过它，转到else语句

@FXML
private void handleSave() {
    File itemFile = mainApp.getItemFilePath();
    if (itemFile != null) {
        mainApp.saveItemDataToFile(itemFile);
    } else {
        handleSaveAs();
    }
}

这是我的另存为代码供参考

@FXML
private void handleSaveAs() {
    FileChooser fileChooser = new FileChooser();

    // Set extension filter
    FileChooser.ExtensionFilter extFilter = new FileChooser.ExtensionFilter(
            "XML files (*.xml)", "*.xml");
    fileChooser.getExtensionFilters().add(extFilter);

    // Show save file dialog
    File file = fileChooser.showSaveDialog(mainApp.getPrimaryStage());

    if (file != null) {
        // Make sure it has the correct extension
        if (!file.getPath().endsWith(".xml")) {
            file = new File(file.getPath() + ".xml");
        }
        mainApp.saveItemDataToFile(file);
    }
}

public File getItemFilePath() {
        Preferences prefs = Preferences.userNodeForPackage(MainApp.class);
        String filePath = prefs.get("Filepath", null);
        if (filePath != null) {
            return new File(filePath);
        } else {
            return null;
        }
    }
public void setItemFilePath(File file) {
    Preferences prefs = Preferences.userNodeForPackage(MainApp.class);
    if (file != null) {
        prefs.put("filePath", file.getPath());

        primaryStage.setTitle("Shopping Basket - " + file.getName());
    } else {
        prefs.remove("filePath");
        primaryStage.setTitle("Shopping Basket");
    }
}


public void loadItemDataFromFile(File file) {
        try {
            JAXBContext context = JAXBContext
                    .newInstance(BasketListWrapper.class);
            Unmarshaller um = context.createUnmarshaller();

            BasketListWrapper wrapper = (BasketListWrapper) um.unmarshal(file);

            itemData.clear();
            itemData.addAll(wrapper.getItems());


            setItemFilePath(file);

        } catch (Exception e) {
            Alert alert = new Alert(AlertType.ERROR);
            alert.setTitle("Error");
            alert.setHeaderText("Could not load data");
            alert.setContentText("Could not load data from file:\n"
                    + file.getPath());

            alert.showAndWait();

        }
    }

    public void saveItemDataToFile(File file) {
        try {
            JAXBContext context = JAXBContext
                    .newInstance(BasketListWrapper.class);
            Marshaller m = context.createMarshaller();
            m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

            BasketListWrapper wrapper = new BasketListWrapper();
            wrapper.setItems(itemData);

            m.marshal(wrapper, file);

            setItemFilePath(file);
        } catch (Exception e) {
            Alert alert = new Alert(AlertType.ERROR);
            alert.setTitle("Error");
            alert.setHeaderText("Could not load data");
            alert.setContentText("Could not load data from file:\n"
                    + file.getPath());

            alert.showAndWait();
        }
    }

Answer 1

在getItemFilePath方法中，您试图获得“Filepath”首选项：

String filePath = prefs.get("Filepath", null);

但是在setItemFilePath方法中，您正在设置“filepath”首选项：

prefs.put("filePath", file.getPath());

因为preferences键是区分大小写的，就像任何其他String一样，您总是会得到默认值，即null