錯誤：沒有為 class 'PlatformButton' 定義方法 'FlatButton'

Question

我收到這些錯誤並且不知道如何修復它們。

../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_button.dart:269:14: Error: The method 'FlatButton' isn't defined for the class 'PlatformButton'.
 - 'PlatformButton' is from 'package:flutter_platform_widgets/src/platform_button.dart' ('../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_button.dart').
Try correcting the name to the name of an existing method, or defining a method named 'FlatButton'.
      return FlatButton(
             ^^^^^^^^^^

../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_button.dart:302:12: Error: The method 'RaisedButton' isn't defined for the class 'PlatformButton'.
 - 'PlatformButton' is from 'package:flutter_platform_widgets/src/platform_button.dart' ('../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_button.dart').
Try correcting the name to the name of an existing method, or defining a method named 'RaisedButton'.
    return RaisedButton(
           ^^^^^^^^^^^^

../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_dialog_action.dart:171:14: Error: The method 'FlatButton' isn't defined for the class 'PlatformDialogAction'.
 - 'PlatformDialogAction' is from 'package:flutter_platform_widgets/src/platform_dialog_action.dart' ('../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_dialog_action.dart').
Try correcting the name to the name of an existing method, or defining a method named 'FlatButton'.
      return FlatButton(
             ^^^^^^^^^^

Answer 1

**Old Widget        change to    New Widget      
FlatButton   =>      TextButton      
RaisedButton =>      ElevatedButton  
OutlineButton =>    OutlinedButton**

有關詳細信息... https://docs.flutter.dev/release/breaking-changes/buttons#context

Answer 2

從 Flutter 文檔中可以看出：

舊的小部件已被刪除，現在您必須使用新的小部件和新的主題。 這是有關如何使用它們的快速指南。

Answer 3

如果您使用的是最新版本的 Flutter，不推薦使用 Flatbutton，請改用 TextButton。

Answer 4

檢查你在pubspec.yaml中添加的最后一個package並刪除它，看看是否沒有錯誤發生那么錯誤是因為package

Answer 5

您只需將 velocity_x:old 版本更改為新版本。 例如：在 pubspec.yaml 依賴項中：velocity_x:^1.4.1 將其更改為 ^3.2.1

Answer 6

new flutter SDK中沒有FlatButton ，使用TextButton代替FlatButton如下：

TextButton(
              style: TextButton.styleFrom(
                foregroundColor: Colors.white,
                padding: const EdgeInsets.all(16.0),
                textStyle: const TextStyle(fontSize: 20),
              ),
              onPressed: () {},
              child: const Text('Gradient'),
            ),