Async - FutureBuilder

 FutureBuilder 

Source Code

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';


void main() {
  runApp(  MaterialApp(
    title:" FutureBuilder ",
    home:Scaffold(appBar: AppBar(title: Text(' FutureBuilder ',),),
      body: Material(
        child: Center(
          child:
          FutureBuilderExample()
          ,
        ),
      ) ,
    ),
  ));
}






class FutureBuilderExample extends StatefulWidget {
  const FutureBuilderExample({Key? key}) : super(key: key);

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

class FutureBuilderExampleState extends State<FutureBuilderExample> {
  Future<ByteData> _wait3SecAndLoadImage() async {
    await Future.delayed(const Duration(seconds: 3));
    return rootBundle.load('images/Codehub.png');
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      alignment: Alignment.center,
      margin: const EdgeInsets.all(8),
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          const Text(
              'In this example we first have an async operatio that takes '
                  '~3 seconds and succeeds with the content of an image from asset.\n'
                  'Note this is just for demonstration purposes, normally we just '
                  'use `Image.asset()`.'),
          FutureBuilder<ByteData>(
            future: _wait3SecAndLoadImage(),
            builder: (BuildContext context, AsyncSnapshot<ByteData> snapshot) {
              if (!snapshot.hasData) {
                return const CircularProgressIndicator();
              } else if (snapshot.hasError) {
                // This shouldn't happen in our case, but good to handle errors.
                return const Text('Error has happened in the future!');
              } else {
                return Image.memory(snapshot.data!.buffer.asUint8List());
              }
            },
          ),
        ],
      ),
    );
  }
}