Q: Select checkboxes items by id I want to create checkbox where users can choose only one item from list clicking by checkbox. I understand that I should use index for achieve my goal, because now I can check all items, not one by one. Also I created hardcoded data which look like the actual data from API.
class CkeckList extends StatefulWidget {
  const CkeckList({Key? key}) : super(key: key);

  @override
  State<CkeckList> createState() => _CkeckListState();
}

class _CkeckListState extends State<CkeckList> {
  List checkListItems = [
    {
      "id": 0,
      "title": "Sunday",
    },
    {
      "id": 1,
      "title": "Monday",
    },
  ];

  int? isChecked;
  bool isSelected = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: ListView.builder(
          itemCount: checkListItems.length,
          itemBuilder: (context, index) {
            return CheckboxListTile(
                title: Text(checkListItems[index]['title']),
                value: isSelected,
                onChanged: (value) {
                  checkListItems[index]['id'] = value;
                });
          }),
    );
  }
}


A: Try this.
 class CkeckList extends StatefulWidget {
  const CkeckList({Key? key}) : super(key: key);

  @override
  State<CkeckList> createState() => _CkeckListState();
}

class _CkeckListState extends State<CkeckList> {
  List checkListItems = [
    {
      "id": 0,
      "title": "Sunday",
    },
    {
      "id": 1,
      "title": "Monday",
    },
  ];

  int? isChecked;
  List<bool> checkedList = [];

  @override
  Widget build(BuildContext context) {

    checkedList.clear();

    checkListItems.forEach((element) {
      checkedList.add(element['id']==0?false:true);
    });

    return Scaffold(
      appBar: AppBar(),
      body: ListView.builder(
          itemCount: checkListItems.length,
          itemBuilder: (context, index) {
            return CheckboxListTile(
                title: Text(checkListItems[index]['title']),
                value: checkedList[index],
                onChanged: (value) {
                  checkListItems[index]['id'] = value;
                 
                });
          }),
    );
  }
}


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

  @override
  State<CkeckList> createState() => _CkeckListState();
}

class _CkeckListState extends State<CkeckList> {
  List checkListItems = [
    {
      "id": 0,
      "title": "Sunday",
    },
    {
      "id": 1,
      "title": "Monday",
    },
  ];

  // if you want to set default selected item you can assign its index here
  int? selectedItemIndex;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: ListView.builder(
          itemCount: checkListItems.length,
          itemBuilder: (context, index) {
            return CheckboxListTile(
                title: Text(checkListItems[index]['title']),
                value: (selectedItemIndex==null)?false:(selectedItemIndex == index),
                onChanged: (value) {
                  checkListItems[index]['id'] = value;
                  selectedItemIndex = index;
                });
          }),
    );
  }
}

