在状态下存储DropdownButton的选定项

Question

我在名为"AddAnnouncementDialogWidgetState"的类中有一个DropdownButton，我希望将所选值存储在AppState中，以便在其他类中使用它。

DropDownButton：

    var _currentItemSelected;
    var _templates = ['birth', 'wedding', 'holiday'];

    ...
     DropdownButton<String>(
                  hint: Text("select a type"),
                items: _templates.map((String dropDownStringItem) {
                  return DropdownMenuItem<String>(
                    value: dropDownStringItem,
                    child: Text(dropDownStringItem),
                  );
                }).toList(),
                onChanged: (String newValueSelected) {
                  setState(() {
                    this._currentItemSelected = newValueSelected;
                  });
                },
                value: _currentItemSelected,
              ),

与_currentItemSelected一起包含所选项目。

AppState类：

    class AppState {
    static var empty = AppState(new List(),User('', ''));

    final List<Announcement> announcements;
    final User user;

    AppState(this.announcements, this.user);

    AppState.fromJson(Map<String, dynamic> json, this.user)
        : announcements = (json['AnnouncementItem'] as List)
        .map((i) => new Announcement.fromJson(i as Map<String, dynamic>))
        .toList();

    Map<String, dynamic> toJson() => {'announcements': announcements};

    }

公告：

    class Announcement {
    String title;
    String description;
    int id;
    String type;

    Announcement(this.title, this.description, this.type);

    Announcement.fromJson(Map<String, dynamic> json): title = json['title'], description = json['description'];

    Map<String, dynamic> toJson() => {'title': title, 'description': description};

    @override
    String toString() {
        return "$title: $description";
    }
    }

我想将所选的礼炮存储在“ type”参数中。

有人对如何做有任何想法吗？