Question

我创建了MapProperty来从数据库中读取信息，如下所示。

命令运行正常，Map，ArrayList正常但错误MapProperty.I希望成员为ListProperty类型，所以我可以将它绑定到控件

public MapProperty<String, ListProperty<String>> mapTaxonomy() {
        MapProperty<String, ListProperty<String>> mapTaxonomy = new SimpleMapProperty<>();
        try {
            preparedStatement = connection.prepareStatement("");
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()) {
                String taxonomy = resultSet.getString("Taxonomy");
                ListProperty<String> memberSelector = mapTaxonomy.get(taxonomy);
                if (memberSelector == null) {
                    memberSelector = new SimpleListProperty<>();
                    mapTaxonomy.put(taxonomy, memberSelector);
                }
                memberSelector.add(resultSet.getString("Selector"));
            }
        } catch (SQLException ex) {
            Logger.getLogger(ParserService.class.getName()).log(Level.SEVERE, null, ex);
        }
        return mapTaxonomy;
    }

@Override
    public void initialize(URL location, ResourceBundle resources) {
        MapProperty<String, ListProperty<String>> mapTaxonomy = mapTaxonomy();
    }

运行以下错误声明后，请帮助我

Caused by: java.lang.UnsupportedOperationException
    at java.util.AbstractMap.put(AbstractMap.java:209)
    at javafx.beans.binding.MapExpression.put(MapExpression.java:262)
    at touya.akira.storages.database.table.parser.ParserService.mapTaxonomy(ParserService.java:70)
    at touya.akira.parser.styles.fixed.method.pagination.PaginationPresenter.initialize(PaginationPresenter.java:64)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
    ... 67 more

Answer 1

SimpleMapProperty的默认值是空 不可修改的 地图。尝试修改它时会引发异常。指定可修改的ObservableMap作为初始值以解决此问题。

MapProperty<String, ListProperty<String>> mapTaxonomy = new SimpleMapProperty<>(FXCollections.observableHashMap());

将数据库读入MapProperty Javafx

1 个答案: