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such as encryption or signal processing.You can run the full example below:
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<code_start>import 'dart:async';
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import 'dart:convert';
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import 'dart:isolate';
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import 'package:flutter/material.dart';
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import 'package:http/http.dart' as http;
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void main() {
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runApp(const SampleApp());
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}
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class SampleApp extends StatelessWidget {
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const SampleApp({super.key});
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@override
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Widget build(BuildContext context) {
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return const MaterialApp(
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title: 'Sample App',
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home: SampleAppPage(),
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);
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}
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}
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class SampleAppPage extends StatefulWidget {
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const SampleAppPage({super.key});
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@override
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State<SampleAppPage> createState() => _SampleAppPageState();
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}
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class _SampleAppPageState extends State<SampleAppPage> {
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List<Map<String, dynamic>> data = <Map<String, dynamic>>[];
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@override
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void initState() {
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super.initState();
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loadData();
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}
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bool get showLoadingDialog => data.isEmpty;
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Future<void> loadData() async {
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final ReceivePort receivePort = ReceivePort();
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await Isolate.spawn(dataLoader, receivePort.sendPort);
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// The 'echo' isolate sends its SendPort as the first message
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final SendPort sendPort = await receivePort.first as SendPort;
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final List<Map<String, dynamic>> msg = await sendReceive(
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sendPort,
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'https://jsonplaceholder.typicode.com/posts',
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);
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setState(() {
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data = msg;
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});
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}
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// The entry point for the isolate
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static Future<void> dataLoader(SendPort sendPort) async {
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// Open the ReceivePort for incoming messages.
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final ReceivePort port = ReceivePort();
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// Notify any other isolates what port this isolate listens to.
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sendPort.send(port.sendPort);
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await for (final dynamic msg in port) {
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final String url = msg[0] as String;
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final SendPort replyTo = msg[1] as SendPort;
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final Uri dataURL = Uri.parse(url);
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final http.Response response = await http.get(dataURL);
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// Lots of JSON to parse
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replyTo.send(jsonDecode(response.body) as List<Map<String, dynamic>>);
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}
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}
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Future<List<Map<String, dynamic>>> sendReceive(SendPort port, String msg) {
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final ReceivePort response = ReceivePort();
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port.send(<dynamic>[msg, response.sendPort]);
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return response.first as Future<List<Map<String, dynamic>>>;
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}
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Widget getBody() {
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if (showLoadingDialog) {
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return getProgressDialog();
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}
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return getListView();
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}
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Widget getProgressDialog() {
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return const Center(child: CircularProgressIndicator());
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}
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ListView getListView() {
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return ListView.builder(
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itemCount: data.length,
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itemBuilder: (context, index) {
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return getRow(index);
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},
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);
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}
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Widget getRow(int index) {
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return Padding(
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padding: const EdgeInsets.all(10),
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child: Text('Row ${data[index]['title']}'),
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);
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}
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@override
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Widget build(BuildContext context) {
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return Scaffold(
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appBar: AppBar(title: const Text('Sample App')),
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body: getBody(),
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);
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}
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}<code_end>
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<topic_end>
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<topic_start>
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How do I make network requests?
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In Xamarin.Forms you would use HttpClient.
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