我正在尝试添加 png 图像，但它没有加载？

Question

我正在尝试制作一个应用程序，通过按下平面按钮，图像应该会改变

这是我的代码。这里的图像无法加载。尽管有我的，它还是抛出了一些异常

pubspec.yaml 文件正确。有人可以帮帮我吗。我正在尝试使用平面按钮内的随机函数来更新按下时的图像。

 import 'package:flutter/material.dart';
    import 'dart:math';
    void main() {
      runApp(Magic());
    }
    class Magic extends StatefulWidget {
      const Magic({Key? key}) : super(key: key);
      @override
      _MagicState createState() => _MagicState();
    }
    
    class _MagicState extends State<Magic> {
      var i=1;
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          home:Scaffold(
            backgroundColor:Colors.blue,
            appBar: AppBar(
              centerTitle: true,
              title:Text( 'Ask Me Anything',
              style: TextStyle(
                  color: Colors.white,
              ),
              ),
              backgroundColor: Colors.blue[900],
            ),
            body: Container(
              child:FlatButton(
                 onPressed: () {
                   setState(() {
                     i = Random().nextInt(5)+1;
                   });
                 },
                child:Image(
                image:AssetImage('images/dice$i.png'),
                )
              ),
            ),
          )
        );
      }
    }
        

我的 Pubspec.yaml 文件

 name: magicball
    description: A new Flutter project.
    
    # The following line prevents the package from being accidentally published to
    # pub.dev using `pub publish`. This is preferred for private packages.
    publish_to: 'none' # Remove this line if you wish to publish to pub.dev
    
    # The following defines the version and build number for your application.
    # A version number is three numbers separated by dots, like 1.2.43
    # followed by an optional build number separated by a +.
    # Both the version and the builder number may be overridden in flutter
    # build by specifying --build-name and --build-number, respectively.
    # In Android, build-name is used as versionName while build-number used as versionCode.
    # Read more about Android versioning at https://developer.android.com/studio/publish/versioning
    # In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
    # Read more about iOS versioning at
    # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
    version: 1.0.0+1
    
    environment:
      sdk: ">=2.12.0 <3.0.0"
    
    dependencies:
      flutter:
        sdk: flutter
    
    
      # The following adds the Cupertino Icons font to your application.
      # Use with the CupertinoIcons class for iOS style icons.
      cupertino_icons: ^1.0.2
    
    dev_dependencies:
      flutter_test:
        sdk: flutter
    
    # For information on the generic Dart part of this file, see the
    # following page: https://dart.dev/tools/pub/pubspec
    
    # The following section is specific to Flutter.
    flutter:
    
      # The following line ensures that the Material Icons font is
      # included with your application, so that you can use the icons in
      # the material Icons class.
      uses-material-design: true
    
      assets:
        - images/ball1.png
        - images/ball2.png
        - images/ball3.png
        - images/ball4.png
        - images/ball5.png
        - images/dice1.png
        - images/dice2.png
        - images/dice3.png
        - images/dice4.png
        - images/dice5.png
        - images/dice6.png
    
      # An image asset can refer to one or more resolution-specific "variants", see
      # https://flutter.dev/assets-and-images/#resolution-aware.
    
      # For details regarding adding assets from package dependencies, see
      # https://flutter.dev/assets-and-images/#from-packages
    
      # To add custom fonts to your application, add a fonts section here,
      # in this "flutter" section. Each entry in this list should have a
      # "family" key with the font family name, and a "fonts" key with a
      # list giving the asset and other descriptors for the font. For
      # example:
      # fonts:
      #   - family: Schyler
      #     fonts:
      #       - asset: fonts/Schyler-Regular.ttf
      #       - asset: fonts/Schyler-Italic.ttf
      #         style: italic
      #   - family: Trajan Pro
      #     fonts:
      #       - asset: fonts/TrajanPro.ttf
      #       - asset: fonts/TrajanPro_Bold.ttf
      #         weight: 700
      #
      # For details regarding fonts from package dependencies,
      # see https://flutter.dev/custom-fonts/#from-packages

这是错误

The following assertion was thrown resolving an image codec:
Unable to load asset: images/dice4.png

When the exception was thrown, this was the stack: 
#0      PlatformAssetBundle.load (package:flutter/src/services/asset_bundle.dart:224:7)
<asynchronous suspension>
#1      AssetBundleImageProvider._loadAsync (package:flutter/src/painting/image_provider.dart:672:14)
<asynchronous suspension>
Image provider: AssetImage(bundle: null, name: "images/dice4.png")
Image key: AssetBundleImageKey(bundle: PlatformAssetBundle#70fe4(), name: "images/dice4.png", scale: 1.0)
====================================================================================================

Answer 1

创建一个assets 文件夹并将images 文件夹放在那里。 并将路径更改为- assets/images/ball1.png。或者你可以把文件夹的引用放在那里。