State dropdown using form builder

address_stats.dart

import 'dart:convert';

const String state_list_map = '{"states" : [{"id" : 1, "name": "Andaman and Nicobar Island"}, '
    '{"id" : 2, "name": "Andhra Pradesh"},'
    '{"id" : 3, "name": "Arunachal Pradesh"},'
    '{"id" : 4, "name": "Assam"},'
    '{"id" : 5, "name": "Bihar"},'
    '{"id" : 6, "name": "Chandigarh"},'
    '{"id" : 7, "name": "Chhattisgarh"},'
    '{"id" : 8, "name": "Dadra and Nagar Haveli"},'
    '{"id" : 9, "name": "Daman and Diu"},'
    '{"id" : 10, "name": "Delhi"},'
    '{"id" : 11, "name": "Goa"},'
    '{"id" : 12, "name": "Gujarat"},'
    '{"id" : 13, "name": "Haryana"},'
    '{"id" : 14, "name": "Himachal Pradesh"},'
    '{"id" : 15, "name": "Jammu and Kashmir"},'
    '{"id" : 16, "name": "Jharkhand"},'
    '{"id" : 17, "name": "Karnataka"},'
    '{"id" : 18, "name": "Kerala"},'
    '{"id" : 19, "name": "Ladakh"},'
    '{"id" : 20, "name": "Lakshadweep"},'
    '{"id" : 21, "name": "Madhya Pradesh"},'
    '{"id" : 22, "name": "Maharashtra"},'
    '{"id" : 23, "name": "Manipur"},'
    '{"id" : 24, "name": "Meghalaya"},'
    '{"id" : 25, "name": "Mizoram"},'
    '{"id" : 26, "name": "Nagaland"},'
    '{"id" : 27, "name": "Odisha"},'
    '{"id" : 28, "name": "Puducherry"},'
    '{"id" : 29, "name": "Punjab"},'
    '{"id" : 30, "name": "Rajasthan"},'
    '{"id" : 31, "name": "Sikkim"},'
    '{"id" : 32, "name": "Tamil Nadu"},'
    '{"id" : 33, "name": "Telangana"},'
    '{"id" : 34, "name": "Tripura"},'
    '{"id" : 35, "name": "Uttar Pradesh"},'
    '{"id" : 36, "name": "Uttarakhand"},'
    '{"id" : 37, "name": "West Bengal"}]}';

class AddressState {

  late int? stateId;
  late String? name;
  late bool? isSelected;

  AddressState(
      {this.name, this.stateId, bool? isSelected}) {
    isSelected = isSelected;
  }

  AddressState copyWith(
      {String? name, int? stateId, bool? isSelected}) {
    AddressState state = AddressState(
        name: name ?? this.name,
        stateId: stateId ?? this.stateId,
        isSelected: isSelected ?? this.isSelected);

    state.isSelected = isSelected ?? this.isSelected;

    return state;
  }

  factory AddressState.fromJson(dynamic json) {
    return AddressState(name: json['name'] as String, stateId: json['id'] as int);
  }

  bool isEqual(AddressState other) {
    return name == other.name;
  }

  @override
  String toString() {
    return 'AddressState{stateId: $stateId, name: $name}';
  }

  static List<AddressState> getStateList() {

    var jsonObjectList = jsonDecode(state_list_map)["states"] as List;

    List<AddressState> stats = jsonObjectList.map((e) => AddressState.fromJson(e)).toList();

    //print(stats);

    return stats;
  }
}

state_widget.dart

class StateWidget extends StatelessWidget {
  
  StateWidget(required this.previousSelectedState);

  final String previousSelectedState;
  late AddressState _businessState;
  
  @override
  Widget build(BuildContext context) {
    return Container(child: _buildStateDropdown(context));
  }

  Widget _buildStateDropdown(BuildContext context) {
    List<AddressState> stateList = AddressState.getStateList();

    if (CommonFunctions.isNullOrEmpty(previousSelectedState)) {
      _businessState = stateList.first;
    } else {
      var tempState = AddressState(name: previousSelectedState);
      _businessState = stateList.firstWhere(
              (element) => element.isEqual(tempState),
          orElse: null);
    }

    return FormBuilderDropdown<AddressState>(
      items: stateList.map((e) {
        return DropdownMenuItem(
          child: Text(e.name!),
          value: e,
        );
      }).toList(),
      name: "addressState",
      initialValue: _businessState,
      isExpanded: true,
      //style: Theme.of(context).textTheme.bodyMedium,
      onChanged: (newValue) {
        _businessState = newValue!;
      },
      decoration: InputDecoration(
        filled: true,
        hintText: S.current.labelState,
        contentPadding: EdgeInsets.only(left: 10, right: 12),
      ),
    );
  }

}