错误警告 Image.asset(......) Flutter, Dart

Question

I'm a beginner in Flutter/Dart programming and I still run all the time in an error when I want to add an image to my app. I want to do it with the widget Image.asset and actually I think I did all the settings in pubspec.yaml and creat as well a new folder assets/images in the project folder so that this one is on the same level like the pubspec.yaml. At first I got some errors like only one dependency or it should be a string so I think I fixed them but since then I get the following Error-warning:

CODE main.dart:

---

import 'dart:ui';
import 'package:flutter/widgets.dart';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
            appBar: AppBar(
              title: Text("TEST-TEST-TEST"), //Titel AppBar
              backgroundColor: Colors.redAccent, //Farbe AppBar
            ),
            body: Center(
                child: Column(children: [
              Text(
                'Hello World :)',
                style: TextStyle(
                    fontSize: 26,
                    fontWeight: FontWeight.bold,
                    color: Colors.blue[800]),
              ),
              Text(
                'Second Line - works ;)',
                style: TextStyle(
                    fontSize: 20,
                    fontWeight: FontWeight.normal,
                    color: Colors.blue[800]),
              ),
              Image.asset(
                'assets/images/pic_1.jpg'),
            ]))));
  }
}

enter code here

CODE pubspec.yaml:

---

name: hello_world

environment:
  # The pub client defaults to an <2.0.0 sdk constraint which we need to explicitly overwrite.
  sdk: ">=2.0.0-dev.68.0 <3.0.0"



dependencies:
  flutter:
   #sdk: flutter 
   assets:
     - assets/images/pic_1.jpg

  


  characters: 1.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  collection: 1.14.13 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  meta: 1.1.8 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  typed_data: 1.2.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  vector_math: 2.0.8 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"

dev_dependencies:
  flutter_driver:
    sdk: flutter
  flutter_test:
    sdk: flutter
  test: 1.15.2

  _fe_analyzer_shared: 5.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  analyzer: 0.39.12 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  archive: 2.0.13 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  args: 1.6.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  async: 2.4.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  boolean_selector: 2.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  charcode: 1.1.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  clock: 1.0.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  convert: 2.1.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  coverage: 0.14.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  crypto: 2.1.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  csslib: 0.16.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  fake_async: 1.1.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  file: 5.2.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  glob: 1.2.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  html: 0.14.0+3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  http: 0.12.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  http_multi_server: 2.2.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  http_parser: 3.1.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  intl: 0.16.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  io: 0.3.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  js: 0.6.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  json_rpc_2: 2.2.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  logging: 0.11.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  matcher: 0.12.8 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  mime: 0.9.6+3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  node_interop: 1.1.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  node_io: 1.1.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  node_preamble: 1.4.12 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  package_config: 1.9.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  path: 1.7.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  pedantic: 1.9.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  pool: 1.4.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  pub_semver: 1.4.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  shelf: 0.7.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  shelf_packages_handler: 2.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  shelf_static: 0.2.8 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  shelf_web_socket: 0.2.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  source_map_stack_trace: 2.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  source_maps: 0.10.9 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  source_span: 1.7.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  stack_trace: 1.9.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  stream_channel: 2.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  string_scanner: 1.0.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  sync_http: 0.2.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  term_glyph: 1.1.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  test_api: 0.2.17 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  test_core: 0.3.10 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  vm_service: 4.1.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  vm_service_client: 0.2.6+2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  watcher: 0.9.7+15 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  web_socket_channel: 1.1.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  webdriver: 2.1.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  webkit_inspection_protocol: 0.7.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
  yaml: 2.2.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"


# PUBSPEC CHECKSUM: f482

Error Warning:

---

[examples/hello_world] flutter pub get Running "flutter pub get" in hello_world...
Because hello_world depends on flutter from unknown source "assets", version solving failed. pub get failed (1; Because hello_world depends on flutter from unknown source "assets", version solving failed.) exit code 1

Answer 1

In my humble opinion, the structure of your pubspec.yaml file is not quite correct. Try declaring the assets under the "flutter" section (yours seem to be under the "dependencies" section, which explains the error message Because hello_world depends on flutter from unknown source "assets" ):

name: hello_world
description: A new Flutter application.

version: 1.0.0+1

environment:
  sdk: ">=2.1.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^0.1.2

dev_dependencies:
  flutter_test:
    sdk: flutter

flutter:
  uses-material-design: true
  assets:
    - assets/images/pic_1.jpg

Answer 2

Your pubspec.yaml part snippet (WRONG)

dependencies:
  flutter:
   #sdk: flutter 
   assets:
     - assets/images/pic_1.jpg

The right way:

#dependencies: //Remove this line
flutter:                       //And 
   #sdk: flutter               // indent
   assets:                     // this block 
     - assets/images/pic_1.jpg // back

When you want to declare flutter assets