Undefined class name 'MaterialApp' in Flutter. How to solve this issue? - android

I created a flutter project using
flutter create first
after i go the codes using vs code and the error shows up saying
undefined class name 'MaterialApp'
how to solve this issue?

This is the problem with the Flutter SDK and the Dart versions. Finally upgraded the flutter sdk and that did the trick. This was suggested here GitHub solution.
Try running the below command in the terminal inside Android Studio
flutter upgrade --force

Related

Cannot find the `flutter.plugin.platforms` key in the `pubspec.yaml`

After hitting pub get, we are getting this "Cannot find the flutter.plugin.platforms key in the pubspec.yaml" error, after reinstalling the android studio we are getting this error for the same project
Make sure you have installed flutter and dart plugin in android studio since you have reinstalled android studio you might have missed this step.
Sometimes few files might be corrupted you can try flutter clean and then flutter pub get to fix it.
If none of the steps helped please provide the flutter doctor -v output in the question.

I have just Installed Flutter, Android Studio, and VS CODE, but I just cant get flutter doctor to eliminate the following error-

I also ran the command flutter doctor --android -licenses but still it shows the error displayed in the image.
I also tried to install android sdk obsolete package from within Android Studio but the package is pre-installed.
What shall I do?
Please Help me, - thanks
Delete android studio permanently and config folder in "User" folder in C:\ . and Delete "SDK" and reinstall Android studio. it probably solve problem

Flutter SDK is not found Android Studio 3.5.3

I have updated my Android Studio, I am facing issue with flutter while creating new flutter project. I have set Environment Variable path as well as checked in cmd everything seems fine, but still it is giving error about Flutter SDK not found. Can any one suggest better solution for this issue ?
First, run flutter doctor, it should tell something, and if it doesn't, issue will probably be with gradle, updating gradle causes a lot of problem, i suggest you delete your gradle located at C:\Users***.gradle, or even the sdk and open android folder of a flutter app in android studio, and let the correct settings install, sync and setup..

Cannot create a new flutter project

I am up to create a new flutter project. But when i do Android studio throws me a error stated in the image below.
And here is the flutter doctor from cmd
PS:- Older flutter projects are working totally fine
I faced the same problem so right now i use Visual Studio Code https://code.visualstudio.com/
Very light compared to Android Studio and easy to use
if you want to use it you should add these extensions
- dart
- flutter
- flutter Files(optional)

Visual Studio Code - Target of URI doesn't exist 'package:flutter/material.dart'

I've just set up my Macbook for flutter development,
So I downloaded flutter SDK, and placed it in my Documents. After, I set up my path variable to work with flutter in my command line.
I execute the command flutter create todolist so I achieve a blank project.
I also set up my visual studio code with Dart-Code so I have the proper syntax highlight, IntelliSense, etc.
So when I open visual studio code, it highlights the import method, like the following image:
This means that it also highlights the classes that are correct, making it completely hard to understand if it's a real error or not.
I have executed both pub get and flutter packages get and got everything correctly.
I have my path variables all correctly.
Why is it highlighting it cannot find that 'import' package?
flutter packages get
Restart Visual Studio Code
source: https://flutter.dev/docs/development/packages-and-plugins/using-packages
flutter clean
flutter packages get
flutter packages upgrade ( Optional - use if you want to upgrade packages )
Restart Android Studio or Visual Studio
Author of the Dart Code plugin here! From the screenshot, I would say this is because your flutter project is in a sub-folder of the folder open in Code. We only scan the opened-folder to check whether it's a Flutter project - which then changes the SDK we launch and also enables the Flutter functionality (like the daemon and debugger).
You should re-open the "todo" folder directly.
If you want to have multiple projects open together, use multi-root workspaces, since Dart Code is multi-root-aware and will check each of the folders in the workspace when deciding if it needs to enable Flutter functionality.
Update
This case should be better supported in the Dart plugin now, so opening the immediate parent folder of a Flutter project should work as expected.
If you have used the flutter packages get command and the error still persists, you can simply reload VS code the Developer: Reload Window command. Simply type that in after pressing Ctrl+Shift+P (Cmd+Shift+P for Mac users). It will clear the error. It's like refreshing VS Code.
Restarting visual studio code worked for me !
Restart the VS Code you will see magic!
If that's not work then check the indent of your dependencies in the pubspec.yaml
Open the project after deleting .idea folder and .dart_tool
This worked for me in Android Studio as well as VS Code. I only had to run these lines in my terminal/command prompt and problem was solved. There was no need to restart any of the IDEs again
flutter packages get
Optionally you also run.
flutter upgrade
-Edit:- Now this happens most of the time to me, whenever I open some old project(flutter project), it is basically because of not downloading or not having the packages to refer, for the vscode, In simple just blindly do A PUB GET or just hit CTRL/COMMAND + s in pubspec.yaml file, and you are good to go(sometimes it might take some time to get everything set(depends on your system specs.))!
-old answer starts here!
Simple thing I did after Someone said here to restart the VSCode and I did that, and now everything works fine.
For me it was because just when I was creating project I got an notification for updating my dart(or related) extension and for that I did it and boom as my project started, it just gave me around 30 errors which do scared but the simple FIX was to RESTART THE EDITOR.
Open the command palette (ctrl+shift+p), type flutter: get packages (should autocomplete); after it resolves open the command palette again and type reload window and execute the command. This should resolve the issue as quickly as possible.
Close the VS Code and Run it again
The quickest way to get Dart-Code to reliably find your Flutter install and use it is to create a new FLUTTER_ROOT environment variable and set it to your Flutter path.
Basically
Check for correct indentation of your package in dependencies
if your editor supports, it automatically runs -> flutter pub get
Either way -> open terminal-> flutter pub get or flutter packages get
check .packages file, see if your package is present else reinstall package
Most important : Restart your IDE (Visual studio or Android Studio)
Start debugging your project
Most probably , your errors will be fixed by then
Hope it works for you
try to run flutter clean
then restart VS Code. This did it for me.
I also had this issue. I had both VS code and Android studio installed in my system.
The error was in VS code.
When i opened the same project on Android studio, the dependency was not actually added to pubsec.yaml. I added it there and ran pub.get.
When I returned to VS Code and everything was working fine.
So, Try opening it in other editor if you have, or through NotePad.
Edit:
Opening widget_test.dart and running it should also solve your issue.
Also happened to me while trying to run the project inside of another directory.
Worked by using the root directory of the main project
Just add
dependencies:
http: ^0.12.0
in pubspec.yaml file
please check http documentation
If you execute From the terminal: "Run flutter packages get" and the error continues, check is all packages directories are listed at '.packages' file. - Sometime you have the packages, but it is not configured at this file.
Execute one of the following:
flutter upgrade
flutter pub get
flutter packages get
Warning! This package referenced a Flutter repository via the
.packages file that is no longer available. The repository from which
the 'flutter' tool is currently executing will be used instead.
running Flutter tool: /opt/flutter previous reference :
/Users/Shared/Library/flutter This can happen if you deleted or moved
your copy of the Flutter repository, or if it was on a volume that is
no longer mounted or has been mounted at a different location. Please
check your system path to verify that you are running the expected
version (run 'flutter --version' to see which flutter is on your
path).
Checking the output of the flutter packages get reveals that the reason in my case was due to moving the flutter sdk.
Do not forget:
export PATH="$PATH:/home/[xxxxx]/flutter/bin
For me, it works:
flutter upgrade
flutter packages get
You can check with
flutter doctor
flutter --version
Go to pubsec.yaml file and add this directly after cupertino_icons:
webview_flutter:
Then press Packages get on the top right corner and it will work fine with you.
Add dependencies.
for example:- import 'package:audioplayers/audio_cache.dart';
in the above package if we only use this package then it shows error
but if we add dependencies in pubspec.yaml
such as
dependencies:
flutter:
sdk: flutter
cupertino_icons: ^0.1.2
audioplayers: ^0.14.1
then click on packages get.
as you see this, I can also insert dependencies so if you insert dependencies along with your package then you are good to go.
If you change the property name in pubspect.yaml all your package in lib folder turn to red with the error Target of URI doesn't exist...
I was using (goggle location picker (with much more customisation in functions and UI) ) so I copy this package(complete) and using in my app in one folder but since dart code analyser analyses one flutter project so I found that those which are referencing from inside of this package is not working then I copy only lib folder(of google location picker) in my original project folder and voila this worked for me.
This solution took me a time of 3 days.
I know this is not the question but it might help someone to save 3 days.
I had this problem in Android Studio with the rflutter_alert package. After inserting the dependencies, I imported the package in my project with ctrl+space key and I have added import 'package:rflutter_alert/'; the problem is that this was not correct. The correct form was package:rflutter_alert/rflutter_alert.dart
right vs wrong comparison
i faced the same issue with the bloc package, after i restarted visual studio i installed the package again using flutter pub add bloc and it installed properly this time. Note that i tried installing it several times, this time it was a charm
Restart you android studio or visual studio.
Run commands
i - flutter clean.
ii - flutter pub get.
iii - flutter upgrade.
if these work not work try this:
Check your dart SDK path.
Don't forget to save pubspec.yaml before running "flutter pub get". Restarting Visual Studio Code is not enough. That was my solution. Sometimes when you work with intellij you forget that ...
When you usually get this error message:
Target of URI doesn't exist: 'package:foo'. Try creating the file
referenced by the URI, or Try using a URI for a file that does exist.
Example:
Target of URI doesn't exist:
'package:random_string/random_string.dart'. Try creating the file
referenced by the URI, or Try using a URI for a file that does exist.
import 'package:random_string/random_string.dart';
It is because a dependency is missing.
So all you have to do is find out what packages are needed by googling your package name.
Install the dependency:
$ flutter pub get
and add the dependency in the pubspec.yaml file:

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