错误：未为类“PlatformButton”定义方法“FlatButton”

Question

我收到这些错误并且不知道如何修复它们。

../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

如果您使用的是最新版本的 Flutter，Flatbutton则 已弃用，请改用TextButton。您可以在此处查看文档

Answer 2

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

for more details... https://docs.flutter.dev/release/breaking-changes/buttons#context

Answer 3

在 flutter 2.1.0 之后， FlatButton已被弃用并从 flutter 中完全删除，使用TextButton代替FlatButton，如下所示：

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