text
stringlengths 1
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|
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return padding( |
padding: const EdgeInsets.all(10), |
child: Text("Row ${widgets[i]["title"]}"), |
); |
} |
future<void> loadData() async { |
ReceivePort receivePort = ReceivePort(); |
await Isolate.spawn(dataLoader, receivePort.sendPort); |
// the 'echo' isolate sends its SendPort as the first message. |
SendPort sendPort = await receivePort.first; |
list msg = await sendReceive( |
sendPort, |
'https://jsonplaceholder.typicode.com/posts', |
); |
setState(() { |
widgets = msg; |
}); |
} |
// the entry point for the isolate. |
static future<void> dataLoader(SendPort sendPort) async { |
// open the ReceivePort for incoming messages. |
ReceivePort port = ReceivePort(); |
// notify any other isolates what port this isolate listens to. |
sendPort.send(port.sendPort); |
await for (var msg in port) { |
string data = msg[0]; |
SendPort replyTo = msg[1]; |
string dataURL = data; |
http.Response response = await http.get(Uri.parse(dataURL)); |
// lots of JSON to parse |
replyTo.send(jsonDecode(response.body)); |
} |
} |
future sendReceive(SendPort port, msg) { |
ReceivePort response = ReceivePort(); |
port.send([msg, response.sendPort]); |
return response.first; |
} |
} |
<code_end> |
<topic_end> |
<topic_start> |
what is the equivalent of OkHttp on flutter? |
making a network call in flutter is easy when you use the |
popular http package. |
while the http package doesn鈥檛 have every feature found in OkHttp, |
it abstracts away much of the networking that you would normally implement |
yourself, making it a simple way to make network calls. |
to add the http package as a dependency, run flutter pub add: |
to make a network call, call await on the async function http.get(): |
<code_start> |
import 'dart:developer' as developer; |
import 'package:http/http.dart' as http; |
future<void> loadData() async { |
var dataURL = uri.parse('https://jsonplaceholder.typicode.com/posts'); |
http.Response response = await http.get(dataURL); |
developer.log(response.body); |
} |
<code_end> |
<topic_end> |
<topic_start> |
how do i show the progress for a long-running task? |
in android you would typically show a ProgressBar view in your UI while |
executing a long-running task on a background thread. |
in flutter, use a ProgressIndicator widget. |
show the progress programmatically by controlling when it鈥檚 rendered |
through a boolean flag. tell flutter to update its state before your |
long-running task starts, and hide it after it ends. |
in the following example, the build function is separated into three different |
functions. if showLoadingDialog is true (when widgets.isEmpty), |
then render the ProgressIndicator. otherwise, render the |
ListView with the data returned from a network call. |
<code_start> |
import 'dart:convert'; |
import 'package:flutter/material.dart'; |
import 'package:http/http.dart' as http; |
void main() { |
runApp(const SampleApp()); |
} |
class SampleApp extends StatelessWidget { |
const SampleApp({super.key}); |
@override |
widget build(BuildContext context) { |
return MaterialApp( |
title: 'sample app', |
theme: ThemeData( |
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple), |
), |
home: const SampleAppPage(), |
); |
} |
} |
class SampleAppPage extends StatefulWidget { |
const SampleAppPage({super.key}); |
@override |
State<SampleAppPage> createState() => _SampleAppPageState(); |
} |
class _SampleAppPageState extends State<SampleAppPage> { |
list widgets = []; |
@override |