CODEWITHSUNDEEP
flutterdart
principemestizo3
principemestizo3

Reputation: 191

Flutter convert Byte to String

So that you have all the context... in python I run the following code: https://www.delftstack.com/es/howto/python/convert-string-to-ascii-python/

def to_ascii(text):
    ascii_values = [ord(character) for character in text]
    return ascii_values
text = input("Enter a string: ")
print(to_ascii(text))

If I write "hello" it throws me the following: [104, 101, 108, 108, 111]

My problem is with Flutter. I get that value and since I don't know flutter I don't know how to put it to text (utf8).

builder: (c, snapshot) {
   final value = snapshot.data;

...

subtitle: Text(value.toString()),

value.toString() return [104, 101, 108, 108, 111]

How do I put it in utf8 ("Hello")?

Complete code:

@override
  Widget build(BuildContext context) {
    return StreamBuilder<List<int>>(
      stream: characteristic.value,
      initialData: characteristic.lastValue,
      builder: (c, snapshot) {
        final value = snapshot.data;

        //convert value ascii to utf8
        //var decoded = utf8.decode(value);

        return ExpansionTile(
          title: ListTile(
            title: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                Text('Characteristic'),
                Text(
                    '0x${characteristic.uuid.toString().toUpperCase().substring(4, 8)}',
                    style: Theme.of(context).textTheme.bodyText1?.copyWith(
                        color: Theme.of(context).textTheme.caption?.color))
              ],
            ),
            subtitle: Text(value),
            contentPadding: EdgeInsets.all(0.0),
          ),
          trailing: Row(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              IconButton(
                icon: Icon(
                  Icons.lightbulb_outline,
                  color: Theme.of(context).iconTheme.color?.withOpacity(0.5),
                ),
                onPressed: turnOff,
              ),
              IconButton(
                icon: Icon(Icons.lightbulb,
                    color: Theme.of(context).iconTheme.color?.withOpacity(0.5)),
                onPressed: turnOn,
              ),
              //iconButton for add
              IconButton(
                icon: Icon(
                  Icons.add_circle,
                  color: Theme.of(context).iconTheme.color?.withOpacity(0.5),
                ),
                onPressed: extraButton,
              ),
              IconButton(
                icon: Icon(
                    characteristic.isNotifying
                        ? Icons.sync_disabled
                        : Icons.sync,
                    color: Theme.of(context).iconTheme.color?.withOpacity(0.5)),
                onPressed: onNotificationPressed,
              )
            ],
          ),
          children: descriptorTiles,
        );
      },
    );
  }
}

Upvotes: 2

Views: 10288

Answers (3)

Elmar
Elmar

Reputation: 4397

In Flutter with built-in dart convert package:

import 'dart:convert';
String convertedValue = utf8.decode(byte);

This will give you the same output as the below Java code:

StringBuilder str = new StringBuilder();
        for (byte aByte : bytesArray) {
            if (aByte != 0) {
                str.append((char) aByte);
            } else {
                break;
            }

Upvotes: 1

navylover
navylover

Reputation: 13549

The demo:

import 'dart:convert';
void main() {
  const asciiDecoder = AsciiDecoder();
  final asciiValues = [104, 101, 108, 108, 111];
  final result = asciiDecoder.convert(asciiValues);
  print(result);  //hello
}

see the ref.

Because maxium ascii code is 127, use Base64Decoder instead.

Upvotes: 4

ImDarkk
ImDarkk

Reputation: 245

import 'dart:convert' show utf8;
var decoded = utf8.decode(value);

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

Upvotes: 7

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