dictionary - flutter 如何从 future 功能访问 map

Question

dart的新手，我想访问userId对象中的Map值，但我不断收到错误消息(请参见注释):

The method 'then' isn't defined for the type 'Function'.
Try correcting the name to the name of an existing method, or defining a method named 'then'.

  Future<Map> getData() async {
    Response load = await get('https://jsonplaceholder.typicode.com/todos/1');
    print(load.statusCode);
    print(load.body);
    Map map = jsonDecode(load.body);
    return map;
  }

  @override
  void initState() {
    var getit = getData;
    print('placeholder');
    getit.then((e){e['userId'];}); // I get an Error here
    super.initState();
  }

Answer 1

问题来自var getit = getData;行
当您提供的方法名称不带括号时(getData)，您会将方法作为对象传递，而不是调用方法并获取其返回值。
要解决此问题，只需通过提供括号来调用该方法:var getit = getData();