Untitled

import 'dart:convert';

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final String _string = '''[[{
    "BD Name": "Deterioration",
    "BD_ID": "6"
},
{
    "BD_Name": "Diagnosis Skill",
    "BD_ID": "3"
},
{
    "BD_Name": "Waiting For Man",
    "BD_ID": "4"
},
{
    "BD_Name": "Waiting For Service Engineer",
    "BD_ID": "2"
},
{
    "BD_Name": "Waiting for spares",
    "BD ID": "1"
},
{
    "BD_Name": "Weak Design",
    "BD_ID": "5"
}],[{
    "BD Name": "Deterioration",
    "BD_ID": "6"
},
{
    "BD_Name": "Diagnosis Skill",
    "BD_ID": "3"
},
{
    "BD_Name": "Waiting For Man",
    "BD_ID": "4"
},
{
    "BD_Name": "Waiting For Service Engineer",
    "BD_ID": "2"
},
{
    "BD_Name": "Waiting for spares",
    "BD ID": "1"
},
{
    "BD_Name": "Weak Design",
    "BD_ID": "5"
}]]''';

  Map<String, String> keyMap = {};
  @override
  void initState() {
    getDropDownReady();
    super.initState();
  }

  List dropDownList = [];
  getDropDownReady() {
    final map = jsonDecode(_string);
    dropDownList = (map as List)
        .map((e) => (e as List).map((e) => e as Map).toList())
        .toList();
    dropDownValueID = dropDownList.map((e) => e[0]['BD_ID']).toList().cast();
  }

  List<String> dropDownValueID = [];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Container(
              color: Colors.grey,
              child: ListView.builder(
                shrinkWrap: true,
                itemCount: dropDownList.length,
                itemBuilder: (context, index) {
                  return DropdownButton<String>(
                    value: dropDownValueID[index],
                    onChanged: (newValue) {
                      setState(() {
                        dropDownValueID[index] = newValue!;
                      });
                    },
                    items:
                        dropDownList[index].map<DropdownMenuItem<String>>((e) {
                      return DropdownMenuItem<String>(
                        value: e["BD_ID"].toString(),
                        child: Text(
                          e["BD_Name"] ?? "",
                          style: const TextStyle(color: Colors.black),
                        ),
                      );
                    }).toList(),
                  );
                },
              ),
            )
          ],
        ),
      ),
    );
  }
}