Writting and Reading files into mobile devices - flutter

Question

I wrote the below code that reads a tring from URL, writting the cotent into a file data.csv then trying to open the file to read its contents as csv but got an error that:
I/flutter ( 6145): FileSystemException: Cannot open file, path =
'data.csv' (OS Error: No such file or directory, errno = 2) I/flutter
( 6145): File is now closed. E/flutter ( 6145):
[ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception:
FileSystemException: Cannot open file, path = 'data.csv' (OS Error:
Read-only file system, errno = 30)
My code is:
import 'dart:convert';
import 'dart:io';
import 'dart:async';
void _incrementCounter() {
setState(() {
new HttpClient().getUrl(Uri.parse('https://docs.google.com/spreadsheets/d/e/2PACX-1vQvf9tp4-fETDJbC-HRmRKvVFAXEAGO4lrYPpVeiYkB6nqqXdSs3CjX0eBMvjIoEeX9_qU6K2RWmzVk/pub?gid=0&single=true&output=csv'))
.then((HttpClientRequest request) => request.close())
// .then((HttpClientResponse response) => response.transform(new Utf8Decoder()).listen(print));
.then((HttpClientResponse response) => response.pipe(new File('data.csv').openWrite()));
final File file = new File("data.csv");
Stream<List> inputStream = file.openRead();
inputStream
.transform(utf8.decoder) // Decode bytes to UTF-8.
.transform(new LineSplitter()) // Convert stream to individual lines.
.listen((String line) { // Process results.
List row = line.split(','); // split by comma
String city = row[0];
String branches = row[1];
print('$city, $branches');
},
onDone: () { print('File is now closed.'); },
onError: (e) { print(e.toString()); });
// List<List<dynamic>> rowsAsListOfValues = const CsvToListConverter().convert(yourString);
_counter++;
});
}

Answer 1

Your code are not running in the order that you think so you will end up trying to read the file before it has been written. I think you code is going to be easier to understand if you use my answer for a other question you have asked: Reading data from url in List
And again, please read: https://dart.dev/codelabs/async-await