Flutter
  • Flutter Tutorials Handbook
  • 01 Flutter: Hello World
    • Related Article
  • 02 Flutter: Stateless Widgets
  • 03 Flutter: Buttons and Stateful widgets
  • 04 Flutter: Basic Navigation & Routes
    • Simple routes using StatelessWidget
    • Routes using StatefulWidget
  • 05 Flutter: Using onChanged to show input text
  • 06 Flutter: Using onSubmitted to show input text after submit
  • 07 Flutter: Adding-Deleting text in TextField
  • 08 Flutter: Tab Navigation
  • 09 Flutter: HTTP requests and Rest API
  • 10 Flutter: ListView with JSON or List Data
  • 11 Flutter: Sliding menu using a Drawer
    • Simple Drawer
    • Drawer using variables
  • 12 Flutter: Animations
  • 13 Flutter: JSON Storage
  • 14 Flutter: Friendly Chat App
  • 15 Flutter: Changing icon color onfocus
  • 16 Flutter: Horizontal ListView and Tabs
  • 17 Flutter: RaisedButton
  • 18 Flutter: RaisedButton with parameters
  • 19 Flutter: FlatButton
  • 20 Flutter: IconButton
  • 21 Flutter: Updating data in TextField
  • 22 Flutter: Checkbox
  • 23 Flutter: Radio with Functions
  • 24 Flutter: Switch
  • 25 Flutter: Slider
  • 26 Flutter: DatePicker
  • 27 Flutter: appBar
  • 28 Flutter: Floating Action Button
  • 29 Flutter: Drawer which shows Toggle Menu
  • 30 Flutter: Footer Buttons
  • 31 Flutter: BottomNavigationBar
  • 32 Flutter: Using BottomSheets
  • 33 Flutter: Using SnackBar
  • 34 Flutter: AlertDialog
  • 35 Flutter: SimpleDialog
  • 36 Flutter: Rows and Columns
  • 37 Flutter: Using Cards
  • 38 Flutter: Using Expanded
  • 39 Flutter: ListviewBuilder using Dart maps
  • 40 Flutter: ListviewBuilder using Dart lists
  • 41 Flutter: Using Custom Widgets
  • 42 Flutter: Using Image Assets
  • 43 Flutter: ListviewBuilder with Refresh Indicator
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39 Flutter: ListviewBuilder using Dart maps

main.dart
import 'package:flutter/material.dart';

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

void main() {
  runApp(new MaterialApp(
    home: new MyApp(),
  ));
}

class MyApp extends StatefulWidget {
  @override
  _State createState() => new _State();
}

//State is information of the application that can change over time or when some actions are taken.
class _State extends State<MyApp> {

  //Map is basically a type of key/value pair in dart
  Map _countries = new Map();

  void _getData() async {
    var url = 'http://country.io/names.json';
    var response = await http.get(url);

    if(response.statusCode == 200) {
      setState(() => _countries = JSON.decode(response.body));
      print('Loaded ${_countries.length} countries');
    }
  }


  @override
  Widget build(BuildContext context) {

    //_getData();

    return new Scaffold(
      appBar: new AppBar(
        title: new Text('Name here'),
      ),
      //hit Ctrl+space in intellij to know what are the options you can use in flutter widgets
      body: new Container(
          padding: new EdgeInsets.all(32.0),
          child: new Center(
            child: new Column(
              children: <Widget>[
                new Text('Countries', style: new TextStyle(fontWeight: FontWeight.bold),),

                /*Listview diplay rows for different widgets,
                Listview.builder automatically builds its child widgets with a
                template and a list*/

                new Expanded(child: new ListView.builder(
                  itemCount: _countries.length,
                  itemBuilder: (BuildContext context, int index){
                    String key = _countries.keys.elementAt(index);
                    return new Row(
                      children: <Widget>[
                        new Text('${key} : '),
                        new Text(_countries[key])
                      ],
                    );
                  },

                ))

              ],
            ),
          )
      ),
    );
  }

  @override
  void initState() {
    _getData();
  }
}
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Last updated 6 years ago