小部件构建-小部件buildItem

Question

你好，我正在尝试创建一个程序，当我单击Container时，它会更改json文件的布尔状态（从true到false或从false到true），但是我无法这样做，因为有人给我以下错误知道我做错了。谢谢您的帮助 ！

错误：
编译器消息：
lib / main.dart：95：7：错误：这些成员的非抽象类“ Program”缺少实现： -State.build
尝试
-提供实施， -从超类或mixin继承实现， -将类标记为抽象，或者 -提供“ noSuchMethod”实现。

类计划扩展了状态{ ^^^^^^^^ ../../Documents/flutter/packages/flutter/lib/src/widgets/framework.dart:1413:10：上下文：此处定义了“ State.build”。 小部件build（BuildContext context）; ^^^^^ 在2323ms内重新启动应用程序。

class Portao extends StatefulWidget {
  @override
  Program createState() => Program();
}

/*--------------------------------------------------*/

class Program extends State<Portao> {

  List _toDoList = [];

  @override
  void initState() {
    super.initState();

    _readData().then((data) {
      setState(() {
        _toDoList = json.decode(data);
      });
    });
  }

  void _addToDo() {
    setState(() {
      Map<String, dynamic> newToDo = Map();
      newToDo['ok'] = true;
      _toDoList.add(newToDo);

      _saveData();
    });
  }

  Future<Null> _refresh() async{
    await Future.delayed(Duration(seconds: 1));
    return null;
  }

  @override
  Widget buildItem(BuildContext context, int index) {

    return Scaffold(
      bottomNavigationBar: CurvedNavigationBar(
        index: 0,
        height: 75,
        items: <Widget>[
          Icon(Icons.home, size: 30, color: Colors.black),  //0
          Icon(Icons.camera_alt, size: 30, color: Colors.black),  //1
          Icon(Icons.build, size: 30, color: Colors.black),  //2
          Icon(Icons.person, size: 30, color: Colors.black), //3
        ],
        color: Colors.white.withOpacity(0.90),
        buttonBackgroundColor: Colors.white.withOpacity(0.90),
        backgroundColor: selected ? Colors.green.withOpacity(0.90) : Colors.deepOrangeAccent.withOpacity(0.90),
        animationCurve: Curves.easeInOut,
        animationDuration: Duration(
            milliseconds: 550
        ),
        onTap: (index) {
          if (index==1)
            Navigator.push(
                context,
                PageTransition(
                    type: PageTransitionType.rightToLeft,
                    child: Camera()
                )
            );
          else if (index==2)
            Navigator.push(
              context,
              PageTransition(
                  type: PageTransitionType.rightToLeft,
                  child:Definicoes()),
            );
          else if (index==3)
            Navigator.push(
              context,
              PageTransition(
                  type: PageTransitionType.rightToLeft,
                  child:infor()),
            );
        },

      ),

      body: Container(
          color: _toDoList[index]['ok'] ? Colors.green.withOpacity(0.90) : Colors.deepOrangeAccent.withOpacity(0.90),
          child:Column(
            children: <Widget>[
              Expanded(
                flex: 5,
                child: Align(
                  child: AnimatedContainer(
                    alignment: _toDoList[index]['ok'] ? Alignment(0, 0.3) : Alignment(0, 0.3),
                    duration: Duration(
                        milliseconds: 600),
                    child: AnimatedContainer(
                      width: _toDoList[index]['ok'] ? 150 : 135,
                      height: _toDoList[index]['ok'] ? 150 : 135,
                      color: Colors.transparent,
                      duration: Duration(
                          milliseconds: 1250),
                      curve: Curves.bounceOut,
                      child: GestureDetector(
                        onTap: () {
                          onChanged: (c){
                            setState(() {
                              _toDoList[index]['ok'] = c;
                              _saveData();
                            });
                          };
                        },
                        child: Container(
                          decoration: BoxDecoration(
                            color: _toDoList[index]['ok'] ? Colors.green.withOpacity(0.90) : Colors.red.withOpacity(0.90),
                            borderRadius: _toDoList[index]['ok'] ? BorderRadius.circular(30) : BorderRadius.circular(40),
                            boxShadow: [
                              BoxShadow(
                                color: Colors.white.withOpacity(0.40),
                                spreadRadius: _toDoList[index]['ok'] ? 10 : 4,
                                blurRadius: 50,
                                offset: Offset(0, 0),
                              ),
                            ],
                          ),
                          child: Center(
                            child: Container(
                              height: 250,
                              width: 250,
                              color: Colors.transparent,
                              child: _toDoList[index]['ok'] ? FlareActor(
                                "animacoes/open.flr", animation: 'open',
                              ): FlareActor(
                                "animacoes/close.flr", animation: 'close',
                              ),
                            ),
                          ),
                        ),
                      ),
                    ),
                  ),
                ),
              ),
              Expanded(
                flex: 5,
                child:Row(
                  children: <Widget>[
                    Expanded(
                      flex: 10,
                      child:Align(
                        alignment:Alignment(0, -0.3),
                        child: Container(
                          width: 250,
                          height: 250,
                          child: (
                              _toDoList[index]['ok'] ? Text(
                                'Portão Fechado',
                                style: TextStyle(
                                  fontWeight: FontWeight.w500,
                                  fontSize: 30,
                                  color: Colors.black,
                                ),
                                textAlign: TextAlign.center,
                              ) : Text(
                                'Portão aberto',
                                style: TextStyle(
                                  fontWeight: FontWeight.w500,
                                  fontSize: 30,
                                  color: Colors.black,
                                ),
                                textAlign: TextAlign.center,
                              )
                          ),
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            ],
          )
      ),
    );
  }

  Future<File> _getFile() async {
    final directory = await getApplicationDocumentsDirectory();
    return File("${directory.path}/data.json");
  }

  Future<File> _saveData() async {
    String data = json.encode(_toDoList);

    final file = await _getFile();
    return file.writeAsString(data);
  }

  Future<String> _readData() async {
    try {
      final file = await _getFile();

      return file.readAsString();
    } catch (e) {
      return null;
    }
  }
}