如何將選定的ListTile傳遞到另一個螢屏？

該頁面將美國各州顯示為串列。當您單擊 ListTile 時，狀態旁邊會出現一個復選標記。用戶只能選擇一種狀態。如何跟蹤點擊的狀態并將其轉移到另一個螢屏？發送按鈕單擊“保存”。

List < UsaStatesModel > _statesList = [];
late final _checkedValue =
  List < bool > .generate(_statesList.length, (index) => false);

@override
Widget bodyWidget(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: 'States'
      actions: GestureDetector(
        onTap: () {},
        child: Icon(
          Icons.save,
          size: 26.0,
        ),
      ),
    ),
    body: BlocConsumer < BlocA, BlocAState > (
      listener: (context, state) {
        if (state is StatesLoadedState) {
          _statesList = state.states;
        }
      },
      builder: (context, state) {
        if (state is StatesLoadedState) {
          return Padding(
            padding: const EdgeInsets.only(top: 142),
              child: ListView.separated(
                itemCount: _statesList.length,
                itemBuilder: (context, index) {
                  return ListTile(
                    trailing: !_checkedValue[index] ?
                    const SizedBox.shrink(): Image.asset(
                        Assets.assetsCheckmark,
                        width: 13,
                        height: 10,
                      ),
                      title: Text(
                        _statesList[index].name,
                      ),
                      onTap: () => _checkState(index),
                  );
                },
                separatorBuilder: (context, index) {
                  return const Divider();
                },
              ),
          ),
        ),
      );
    }
  }
)
}

void _checkState(int index) {
  setState(
    () {
      for (var i = 0; i < _checkedValue.length; i  ) {
        _checkedValue[i] = false;
      }
      _checkedValue[index] = true;
    },
  );
}
}

uj5u.com熱心網友回復：

在頂部創建一個像這樣的變數

int currentIndex = 0;

Whenever a list is selected update this index

void _checkState(int index) {
  setState(
    () {
      for (var i = 0; i < _checkedValue.length; i  ) {
        _checkedValue[i] = false;
      }
      _checkedValue[index] = true;
     currentIndex = index; //update here
    },
  );
}

現在

_stateList[currentIndex]

會給你當前選擇的狀態

uj5u.com熱心網友回復：

您不能傳遞 Listtile，它會占用記憶體，所以我認為您必須使用引數僅將資料從一個螢屏傳遞到另一個螢屏，就像這樣。

import 'package:flutter/src/foundation/key.dart';
import 'package:flutter/src/widgets/framework.dart';

class MyWidget extends StatefulWidget {
  const MyWidget({Key? key}) : super(key: key);

  @override
  State<MyWidget> createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
body: Container(
  child: ElevatedButton(onPressed: () {  

    Navigator.of(context).push(MaterialPageRoute(builder: (context){
      return secondscreen(data:"hello");
    }));
  },
  child: Text("hwllo"),),
),
    );
  }
}

class secondscreen extends StatefulWidget {

  String data;
   secondscreen({Key? key,required this.data}) : super(key: key);

  @override
  State<secondscreen> createState() => _secondscreenState();
}

class _secondscreenState extends State<secondscreen> {
  @override
  Widget build(BuildContext context) {
    return Text('${widget.data}');
  }
}```

uj5u.com熱心網友回復：

我們可以在頂部的這個螢屏中擁有 selectedIndex 屬性，并在 _checkState 方法中為其賦值。在我們的第二個螢屏（我們必須將選定狀態傳遞到的螢屏）中，我們需要創建一個 UsaStatesModel 變數并在導航時為其賦值。

 int? selectedIndex;


void _checkState(int index) {
  selectedIndex = index; // Assigning selected index value
  setState(
    () {
      for (var i = 0; i < _checkedValue.length; i  ) {
        _checkedValue[i] = false;
      }
      _checkedValue[index] = true;
    },
  );
}

// Call this method on save to pass selected state to another screen
    goToAnotherScreen(BuildContext context) {
      if (selectedIndex != null) {
        final selectedState = _statesList[selectedIndex!];
        Navigator.push(
          context,
          MaterialPageRoute(
            builder: (context) => SecondScreen(selectedState: selectedState),
          ),
        );
      }
    }

第二屏

class SecondScreen extends StatelessWidget {
      const SecondScreen({
        Key? key,
        required this.selectedState,
      }) : super(key: key);
    
      UsaStatesModel selectedState;
    
      @override
      Widget build(BuildContext context) {
        return Container();
      }
    }

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