Flutter App to simulate data loading

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  bool _isLoading = true;
  List<Map<String, dynamic>> _data = [];
  
  Future<List<Map<String, dynamic>>> simulatedAPI() async {
    await Future.delayed(Duration(seconds: 3));
    return [
      {
        "fname": "Arpan",
        "lname": "Mukherjee"
      },
      {
        "fname": "Arnab",
        "lname": "Sen"
      },
    ];
  }
  
  initState() {
    super.initState();
    loadData();
  }
  
  loadData() async {
    setState(() {
      _isLoading = true;
    });
    
    var dataTemp = await simulatedAPI();
    
    setState(() {
      _isLoading = false;
      _data = dataTemp;
    });
  }
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Data Loaded App"),
      ),
      body: Container(
        child: _isLoading ? Center(
          child: CircularProgressIndicator(),        
        ) : ListView.builder(
          itemCount: _data.length,
          itemBuilder: (context, index) {
            
            var person = _data[index];
            
            return ListTile(
              title: Text("${person["fname"]} ${person["lname"]}")
            );
          }
        ),
      ),
     
      floatingActionButton: FloatingActionButton(
        onPressed: loadData,
        child: Icon(Icons.refresh),
      ),
    );
  }
}