use of HexEncoder class from flutter

Question

I am trying to use the class HexEncoder from https://docs.flutter.io/flutter/convert/HexEncoder-class.html and i can't make it work. Actually i am doing this to convert a list of bytes to a string:

import 'dart:convert';
import 'package:convert/convert.dart';

HexEncoder _hexEncoder;
List<int> value = [253, 165, 6, 147, 164, 226, 79, 177, 175, 207, 198, 235, 7, 100, 120, 37]
_hexEncoder.convert(value);

but throws me the error:

 The method 'convert' was called on null

Sorry for my poor knowledge of dart/flutter. I know i amb calling a null object, i just need to know the way to use this class. Thank you so much !

Answer 1

This should do what you want:

import 'package:convert/convert.dart';

List<int> value = [253, 165, 6, 147, 164, 226, 79, 177, 175, 207, 198, 235, 7, 100, 120, 37];
var result = hex.encode(value);

This code

HexEncoder _hexEncoder;

just declares a variable _hexEncoder but doesn't initialize it with an encoder instance or any other value and therefor is null.