dart

问题 I want to upload multiple-images using Dio and multi_image_picker plug-in in Flutter. List<Asset> this is the problem because I can't convert from List<Asset> to List<File> so if you have any solutions help me. try to use: multi_image_picker: ^4.6.1 dio: ^3.0.4 Thanks Bona SR. import 'dart:io'; import 'package:dio/dio.dart'; import 'package:flutter/material.dart'; import 'package:flutter_secure_storage/flutter_secure_storage.dart'; import 'package:merchantside/helper/colorhelper.dart'; import

问题 I want to upload multiple-images using Dio and multi_image_picker plug-in in Flutter. List<Asset> this is the problem because I can't convert from List<Asset> to List<File> so if you have any solutions help me. try to use: multi_image_picker: ^4.6.1 dio: ^3.0.4 Thanks Bona SR. import 'dart:io'; import 'package:dio/dio.dart'; import 'package:flutter/material.dart'; import 'package:flutter_secure_storage/flutter_secure_storage.dart'; import 'package:merchantside/helper/colorhelper.dart'; import

问题 The Dart core API has two classes that implement the Queue<E> interface, DoubleLinkedQueue<E> and ListQueue<E>. The documentation of both classes is almost identical, the only difference that is explicitly mentioned is the following note in the ListQueue<E> documentation: Operations like removeAll and removeWhere are very inefficient. If those are needed, use a DoubleLinkedQueue instead. What is the actual difference between them implementation-wise and when should which implementation be

问题 The Dart core API has two classes that implement the Queue<E> interface, DoubleLinkedQueue<E> and ListQueue<E>. The documentation of both classes is almost identical, the only difference that is explicitly mentioned is the following note in the ListQueue<E> documentation: Operations like removeAll and removeWhere are very inefficient. If those are needed, use a DoubleLinkedQueue instead. What is the actual difference between them implementation-wise and when should which implementation be

问题 The Dart core API has two classes that implement the Queue<E> interface, DoubleLinkedQueue<E> and ListQueue<E>. The documentation of both classes is almost identical, the only difference that is explicitly mentioned is the following note in the ListQueue<E> documentation: Operations like removeAll and removeWhere are very inefficient. If those are needed, use a DoubleLinkedQueue instead. What is the actual difference between them implementation-wise and when should which implementation be

问题 I have created a flutter web project which uses network images and asset images, everything works fine when debugging on my pc but when I deploy it to a web server, the network images work fine but the asset images dont show at all. When I Inspect the page in the web browsers consol, I get the error below: $1 @ window.dart:120 /assets/slack.png:1 Failed to load resource: the server responded with a status of 503 () window.dart:120 Error while trying to load an asset: Failed to load asset at

问题 Is there any library available to save object and restore it. In android java we using Gson to do this but in flutter there is no Gson 回答1: A library like GSON won't be possible in Flutter, since Flutter doesn't support code reflection. Reflection interferes with tree shaking which flutter needs to clean out unused code and give a compact app. more on the topic and alternatives here You can use this site to convert your JSONs to class and it prepares the toJson fromJson methods automatically.

问题 I have been using VSCode for flutter development without issue, then today all of a sudden the dart analyzer is complaining that the majority of the classes are undefined, or targets do not exists. Has anyone seen this before? I have restarted VSCode, restarted computer, uninstalled flutter/dart plugins, ran flutter doctor with no issues...I am out of ideas. VSCode Issues 回答1: Go to pubspec.yaml , right click and do Get Packages . It seems to work for me all the time. 回答2: The issue might be

问题 I am very new to Dart/Flutter and I have a confusion regarding the => notation. The documentation says that the => notation is used as a shorthand to return a single expression. bool isNoble(int atomicNumber) => _nobleGases[atomicNumber] != null; My doubt comes when I am trying to set state in a flutter application. RaisedButton( onPressed: () => { setState(() { print('hello'); _products.add('More stuff'); }) }, child: Text('Add Product'), ), Now when i change the setState method with =>

问题 I know that this keyword should be used in some custom library, but when I dropped it, nothing happened (at least I didn't notice anything), imports still worked fine, private members remained private. Could somebody explain what "library" keyword in Dart do? 回答1: update 2018-03-05 For a while now, part of accepts a URI, which reduces the need of library to a few edge cases. update 2015-11-27 With a recent change, two imported nameless libraries don't produce a warning anymore. The plan is to