How can I convert string to utf8 in Dart?

Question

I am using aqueduct web api framework to support my flutter app. In my api backend I need to connect local network socket services. My problem is that I can't return the exact string (in tr). So, How can I convert string to utf8 in Dart?

Example:

@httpGet
Future<Response> getLogin() async {
    Socket.connect('192.168.1.22', 1024).then((socket) async {
    socket.listen((data) {
        // Expected return is: 1:_:2:_:175997:_:NİYAZİ TOROS
        print(new String.fromCharCodes(data).trim());
        xResult = new String.fromCharCodes(data).trim();
        print("xResult: $xResult");
    }, onDone: () {
        print("Done");
        socket.destroy();
    });

    socket.write('Q101:_:49785:_:x\r\n');
    });

    return new Response.ok(xResult);
}

The return is not in TR-tr language format.

Return text looks like:

**1:_:2:_:175997:_:NÝYAZÝ TOROS**

Correct must be:

**1:_:2:_:175997:_:NİYAZİ TOROS**

UPDATE:

xResult = new String.fromCharCodes(data).trim();
print(xResult);
responseBody = xResult.transform(utf8.decoder);
print(responseBody);

I can print the xResult but cannot print the responseBody after trying convert to UTF8

in the 4. step is not printing. means responseBody is null, meaning utf8.decoder didn't do anything — , Jun 29 '18 at 12:56
Ok. I cenge it to responseBody = utf8.decode(xResult); and still can't print responseBody — , Jun 29 '18 at 13:19
Hard to tell without more concrete information. Perhaps you need `print(utf8.decode(data));` — Günter Zöchbauer, Jun 29 '18 at 13:30
it prints the first one like print("xResult: $xResult"); but doesnt print second one. print(utf8.decode(data)); than I put only print(utf8.decode(data)); and still didn't print anything. Only prints this line; xResult = new String.fromCharCodes(data).trim(); print("xResult: $xResult"); — , Jun 29 '18 at 13:40
I can print as 1::2::175997:_:NÝYAZÝ TOROS. But all the character Ý must be İ — , Jun 29 '18 at 13:47
and if I say print(data) I get this: [49, 58, 95, 58, 50, 58, 95, 58, 54, 50, 51, 52, 51, 48, 58, 95, 58, 78, 221, 89, 65, 90, 221, 32, 84, 79, 82, 79, 83, 13, 10] — , Jun 29 '18 at 13:48
Your data seems to be encoded as Latin-5 (https://en.wikipedia.org/wiki/ISO/IEC_8859-5). Dart does not have a built-in decoder for Latin-5 (only Latin-1 because that is a direct subset of Unicode code points so conversion is trivial). You will have to manually convert between Latin-5 and Unicode code points. When that is done, you can create a String using Strong.fromCharCodes. — lrn, Jun 29 '18 at 15:47
My bad, I was thinking of *Windows* Latin 5, not ISO Latin 5. Turkish is probably ISO Latin 9 instead. — lrn, Jul 03 '18 at 09:15
Thanks Irn, I use simple switch statement to replace the character. I know the differences between Latin 1 and 9. — , Jul 03 '18 at 10:17
.runes.toList() for a String https://stackoverflow.com/questions/61496673/how-to-add-utf8-decoder-to-solve-the-problem-of-garbled-characters-in-flutter-ht — giorgio79, Jul 21 '21 at 03:18

score 51 · Accepted Answer · edited Jun 04 '19 at 02:49

51

import 'dart:convert' show utf8;

var encoded = utf8.encode('Lorem ipsum dolor sit amet, consetetur...');
var decoded = utf8.decode(encoded);

See also https://api.dartlang.org/stable/1.24.3/dart-convert/UTF8-constant.html

There are also encoder and decoder to be used with streams

File.openRead().transform(utf8.decoder).

See also https://www.dartlang.org/articles/libraries/converters-and-codecs#converter

edited Jun 04 '19 at 02:49

Max

11
4

answered Jun 29 '18 at 12:19

Günter Zöchbauer

623,577
216
2,003
1,567

1

`File.openRead().transform(utf8.encoder)` is give an error – Rohit Nishad Jun 30 '20 at 11:07
1

List fileBytes = await file.readAsBytes(); Then used the utf8.decode(fileBytes). works as per the requirement. :) – Rakesh Verma Dec 22 '22 at 13:33

score 21 · Answer 2 · answered Feb 07 '20 at 09:10

21

utf8.decode(stringData.runes.toList()),

This could be used to get the UTF-8 in flutter. here the stringData string will contain the necessary data with UTF-8 content.

answered Feb 07 '20 at 09:10

Jithin U. Ahmed

1,495
1
19
29

score 2 · Answer 3 · answered Oct 03 '21 at 08:12

Try to use utf-8 convertion Use this code

 final message =  utf8.decode(data);

Instead of this

final message = String.fromCharCodes(data);

import

 import 'dart:convert';

 void handleConnection(Socket client) {
print('Connection from'
    ' ${client.remoteAddress.address}:${client.remotePort}');

// listen for events from the client
client.listen(
  // handle data from the client
  (Uint8List data) async {
    await Future.delayed(Duration(seconds: 1));
    final message =  utf8.decode(data);
    // final message = String.fromCharCodes(data);
    int length = messageWidgets.length;
    Widget padding2 = Padding(
      padding: const EdgeInsets.all(8.0),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.start,
        children: [
          Expanded(
            flex: 1,
            child: GestureDetector(
                onLongPress: () {
                  _copy(message);
                },
                onDoubleTap: () {
                  setState(() {
                    messageWidgets.removeAt(length);
                  });
                },
                child: Container(
                  padding: EdgeInsets.all(8.0),
                  decoration: BoxDecoration(
                    borderRadius: BorderRadius.circular(10),
                    color: Color(0xDD44871F),
                  ),
                  child: Stack(
                    children: <Widget>[
                      Column(
                        // direction: Axis.vertical,
                        children: [
                          Text("${client.remoteAddress.host}::-",
                              style: TextStyle(color: Colors.black87)),
                          Text("${message}",
                              style: TextStyle(color: Colors.black87)),
                        ],
                      )
                    ],
                  ),
                )),
          ),
          Expanded(
            flex: 1,
            child: Container(),
          ),
        ],
      ),
    );
    setState(() {
      messageWidgets.add(padding2);
    });
  },

  // handle errors
  onError: (error) {
    print(error);
    setMwidget(error);
    client.close();
  },

  // handle the client closing the connection
  onDone: () {
    print('Client left');
    client.close();
  },
);

}

score 1 · Answer 4 · answered Aug 27 '22 at 15:11

This is not the solution for your specific case but relative to the title.

If your string is a Uri, use:

final decodedUri = Uri.decodeFull('your-string-uri')

Android string Uri is an example use case, here is a demo before and after using Uri.decodeFull():

score 0 · Answer 5 · answered Sep 09 '22 at 01:37

0

To/from Uint8List

//Uint8List to String
Uint8List bytes = utf8.encode(String s) as Uint8List;

//String to Uint8List
String s = utf8.decode(bytes.toList());

answered Sep 09 '22 at 01:37

CNK

567
5
6

score 0 · Answer 6 · answered Dec 15 '22 at 04:25

Useful related convertions:

import 'dart:convert';
import 'dart:typed_data';

// Text to byte:
List<int> byteIntList = utf8.encode('yourTextHere');

// Text to Uint8List:
Uint8List myUint8List = utf8.encode('yourTextHere') as Uint8List;

// List<int> to Uint8List:
Uint8List myUint8List = Uint8List.fromList(byteIntList);

score 0 · Answer 7 · answered Aug 25 '23 at 12:39

0

import 'dart:convert';

const originalString = 'En EspaÃ±ol'; 
final decodedString = utf8.decode(originalString.codeUnits);
print(decodedString); // prints 'En Español'

Just an alternative in case you have to convert strings.

answered Aug 25 '23 at 12:39

RoHaN

372
3
14

How can I convert string to utf8 in Dart?

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