Flutter 如何成功构建颤振画廊应用程序？

我试着建立一个关于颤振的图库应用程序，结果却出现了两次同样的错误。你能帮我建一下吗？NB：我跑了

flutter run -d macos

以下是错误：

lib/demos/material/picker_demo.dart:23:9: Error: Type 'RestorableTimeOfDay' not found.

最终可恢复日期时间\u fromTime=可恢复日期时间（
^^^^^^^^^^^^^^^^^^^
lib/demos/material/picker\u demo.dart:23:9:错误：“RestorableTimeOfDay”不是一种类型。 最终可恢复日期时间\u fromTime=可恢复日期时间（
^^^^^^^^^^^^^^^^^^^
lib/demos/material/picker\u demo.dart:23:41:错误：找不到方法：“RestorableTimeOfDay”。 最终可恢复日期时间\u fromTime=可恢复日期时间（
^^^^^^^^^^^^^^^^^^^
lib/demos/material/picker\u demo.dart:88:16:错误：找不到方法：“TimePickerDialog”。 返回时间选择器对话框(

---

感谢您的帮助

这些错误是由于我在稳定频道上

$ flutter channel
Flutter channels:
  master
  dev
  beta
* stable

正如github页面所示，必须使用主通道

$ flutter channel master
Switching to flutter channel 'master'...
git: From https://github.com/flutter/flutter
git:  + f9c825981c...fa5883b78e dev            -> origin/dev  (forced update)
git:  * [new branch]            flutter-2.3-candidate.19 -> origin/flutter-2.3-candidate.19
git:  * [new branch]            flutter-2.3-candidate.20 -> origin/flutter-2.3-candidate.20
git:  * [new branch]            flutter-2.3-candidate.21 -> origin/flutter-2.3-candidate.21
git:  * [new branch]            flutter-2.3-candidate.22 -> origin/flutter-2.3-candidate.22
git:    58ac7b85d9..811f0d9a15  master         -> origin/master
git:  * [new tag]               2.3.0-16.0.pre -> 2.3.0-16.0.pre
git: Switched to a new branch 'master'
git: Branch 'master' set up to track remote branch 'master' from 'origin'.
Successfully switched to flutter channel 'master'.
To ensure that you're on the latest build from this channel, run 'flutter upgrade'

$ flutter upgrade
Downloading Dart SDK from Flutter engine 03d645e782db18812d33a843f61c7b220f3db107...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  216M  100  216M    0     0  8057k      0  0:00:27  0:00:27 --:--:-- 8515k
Building flutter tool...
Flutter is already up to date on channel master
Flutter 2.3.0-17.0.pre.223 • channel master • https://github.com/flutter/flutter.git
Framework • revision 811f0d9a15 (4 hours ago) • 2021-06-04 22:14:03 -0700
Engine • revision 03d645e782
Tools • Dart 2.14.0 (build 2.14.0-182.0.dev)

$ flutter channel
Downloading package sky_engine...                                  883ms
Downloading flutter_patched_sdk tools...                           977ms
Downloading flutter_patched_sdk_product tools...                   616ms
Downloading linux-x64 tools...                                      3.8s
Downloading linux-x64/font-subset tools...                         562ms
Flutter channels:
* master
  dev
  beta
  stable

现在它运行：

$flatter运行
下载linux-x64/linux-x64-flatter-gtk工具…2750ms
正在下载linux-x64-profile/linux-x64-flatter-gtk工具…1810ms
下载linux-x64-release/linux-x64-flatter-gtk工具…2001毫秒
在画廊中运行“颤振酒吧”2791ms
在Linux上以调试模式启动lib/main.dart。。。
正在构建Linux应用程序。。。
正在将文件同步到设备Linux…635ms
颤振运行键命令。
r热重新加载。可能尝试运行
flatter clean
，然后再次运行
flatter run
？感谢您的评论。但我仍然收到一个错误：gallery%flatter run-d macos在gallery中运行“flatter pub get”…1 244ms在调试模式下在macOS上启动lib/main.dart…正在运行pod安装…1 621ms lib/demos/material/picker\u demo.dart:23:9:错误：未找到类型“RestorableTimeOfDay”。最终RestorableTimeOfDay _fromTime=RestorableTimeOfDay（这就是你对Flatter gallery的意思吗？如果不是，这是一个预先制作的项目，还是你自己制作的？是的，就是这样，我刚刚对它进行了git克隆。如果可能，你可以删除它并再次进行git克隆吗？如果你自己做了更改，请在线保存。你也运行了
Flatter pub get
？