dart

问题 After switched to branch 'stable' flutter channel The following is the build issue. Error: The specified language version is too high. The highest supported language version is 2.8. output: ../../third_party/dart/third_party/pkg/collection/lib/src/utils.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.8. // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file ^ ../../third_party/dart/third_party/pkg/collection/lib

问题 After switched to branch 'stable' flutter channel The following is the build issue. Error: The specified language version is too high. The highest supported language version is 2.8. output: ../../third_party/dart/third_party/pkg/collection/lib/src/utils.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.8. // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file ^ ../../third_party/dart/third_party/pkg/collection/lib

问题 After switched to branch 'stable' flutter channel The following is the build issue. Error: The specified language version is too high. The highest supported language version is 2.8. output: ../../third_party/dart/third_party/pkg/collection/lib/src/utils.dart:1:1: Error: The specified language version is too high. The highest supported language version is 2.8. // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file ^ ../../third_party/dart/third_party/pkg/collection/lib

问题 I am new to flutter and am trying to implement custom list view in flutter. Its giving be RenderCustomMultiChildLayoutBox object was given an infinite size during layout error I am not able to get for which widget its throwing error 2 Also please suggest how to debug these layout errors as the error trace doesn't have specific widget info for which error is thrown please find the below code for the same: class ChatItemSreen extends StatelessWidget { var leftSection; var middleSection; var

问题 Assume I have a list like: var letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']; I would like a list of lists of 2 elements each: var chunks = [['a', 'b'], ['c', 'd'], ['e', 'f'], ['g', 'h']]; What's a good way to do this with Dart? 回答1: Here is another way: var chunks = []; for (var i = 0; i < letters.length; i += 2) { chunks.add(letters.sublist(i, i+2 > letters.length ? letters.length : i + 2)); } return chunks; 回答2: Quiver (version >= 0.18) supplies partition() as part of its iterables

问题 Assume I have a list like: var letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']; I would like a list of lists of 2 elements each: var chunks = [['a', 'b'], ['c', 'd'], ['e', 'f'], ['g', 'h']]; What's a good way to do this with Dart? 回答1: Here is another way: var chunks = []; for (var i = 0; i < letters.length; i += 2) { chunks.add(letters.sublist(i, i+2 > letters.length ? letters.length : i + 2)); } return chunks; 回答2: Quiver (version >= 0.18) supplies partition() as part of its iterables

问题 I have a JSON file in the flutter directory, not in assets. json_data.json:- { "foo" : "bar" } I want to read this JSON on different files. like myfile.dart:- import "package:mypackage/json_data.json" as data; import 'dart:convert'; var my_data = json.decode(data); I am getting the error:- The name 'data' refers to an import prefix, so it must be followed by '.'. Try correcting the name to refer to something other than a prefix, or renaming the prefix. What is the problem here? why can't I

问题 I have a JSON file in the flutter directory, not in assets. json_data.json:- { "foo" : "bar" } I want to read this JSON on different files. like myfile.dart:- import "package:mypackage/json_data.json" as data; import 'dart:convert'; var my_data = json.decode(data); I am getting the error:- The name 'data' refers to an import prefix, so it must be followed by '.'. Try correcting the name to refer to something other than a prefix, or renaming the prefix. What is the problem here? why can't I

问题 I am using a various plugin to get user data, contact, photos and camera when the user clicks Don't allow, The application goes silent. I want to show the user the ask permission dialog when the user checks the Never ask again and Don't allow and enters the application again. Currently the app never ask to again when the user checks Don't allow I Know Users must grant permission for an app to access personal information, including the current location , camera , calendar , contacts ,

问题 I am using a various plugin to get user data, contact, photos and camera when the user clicks Don't allow, The application goes silent. I want to show the user the ask permission dialog when the user checks the Never ask again and Don't allow and enters the application again. Currently the app never ask to again when the user checks Don't allow I Know Users must grant permission for an app to access personal information, including the current location , camera , calendar , contacts ,