Flutter 颤振：使用SharedReferences将项目ID保存到字符串列表

我想用SharedReferences将项的Id存储到favId（字符串列表）中。我创建了saveData和getData方法，如下所示：

  static List<String> favId = [];

  void saveData() async {
    SharedPreferences pref = await SharedPreferences.getInstance();
    pref.setStringList("id", favId);
  }

  getList() async {
    SharedPreferences pref = await SharedPreferences.getInstance();
    return pref.getStringList("id");
  }

这是我的全部代码

IconButton(
                icon: Icon(
                  doa.fav ? Icons.favorite : Icons.favorite_border,
                  color: doa.fav ? Colors.red : Colors.grey,
                ),
                onPressed: () => setState(() {
                  doa.fav = !doa.fav;
                  if (favId.contains(doa.id)) {
                    favId.removeWhere(
                        (element) => element == doa.id.toString());
                  } else {
                    favId.add(doa.id.toString());
                    saveData();
                  }
                }),
              ),