gistfile1.txt

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'dart:async';
import 'dart:convert';

class Register2 extends StatefulWidget {
  @override
  _RegisterState2 createState() => _RegisterState2();
}

class _RegisterState2 extends State<Register2> {
  Estados _current;

  //final String uri = 'https://jsonplaceholder.typicode.com/users';
  final String uri = 'http://www.deltainternet.net.br/api/v1.0/states';

  Future<List<Estados>> _fetchUsers() async {
    var response = await http.get(uri);

    if (response.statusCode == 200) {
      final items = json.decode(response.body).cast<Map<String, dynamic>>();
      List<Estados> listOfUsers = items.map<Estados>((json) {
        return Estados.fromJson(json);
      }).toList();

      return listOfUsers;
    } else {
      throw Exception('Failed to load internet');
    }
  }

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

  @override
  Widget build(BuildContext context) {
    GlobalKey<FormState> _formKey = GlobalKey<FormState>();

    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.white,
        elevation: 0.0,
        title: Text(''),
        iconTheme: IconThemeData(
          color: Colors.purple,
        ),
      ),
      body: Container(
          color: Colors.white24,
          child: SingleChildScrollView(
            child: Form(
              key: _formKey,
              autovalidate: true,
              child: Column(
                children: <Widget>[
                  FutureBuilder<List<Estados>>(
                      future: _fetchUsers(),
                      builder: (BuildContext context,
                          AsyncSnapshot<List<Estados>> snapshot) {
                        if (!snapshot.hasData)
                          return CircularProgressIndicator();
                        return DropdownButton<Estados>(
                          items: snapshot.data
                              .map((data) => DropdownMenuItem<Estados>(
                                    child: Text(data.name),
                                    value: data,
                                  ))
                              .toList(),
                          onChanged: (Estados value) {
                            setState(() {
                              _current = value;
                            });
                          },
                          isExpanded: true,
                          //value: _current,
                          hint: Text('Selecione o estado'),
                        );
                      }),
                  SizedBox(height: 20.0),
                  _current != null
                      ? Text("Estado: " + _current.name)
                      : Text("Nenum estado selecionado"),
                ],
              ),
            ),
          )),
    );
  }
}

class Estados {
  int id;
  String name;

  Estados({
    this.id,
    this.name,
  });

  factory Estados.fromJson(Map<String, dynamic> json) {
    return Estados(
      id: json['id'],
      name: json['name'],
    );
  }
}