flutter import android.support.annotation.NonNull

Question

So, I wanted to use firebase_auth in the flutter, but I was having androidX.annotation.NonNull error I made a few changes in android files and after a lot of jumble mumble I fixed the error but now I get

Error

C:\Users\Dell\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:8: error: package android.support.annotation does not exist
import android.support.annotation.NonNull;
                                 ^
C:\Users\Dell\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:538: error: cannot find symbol
    public void onComplete(@NonNull Task<AuthResult> task) {
                            ^
  symbol:   class NonNull
  location: class FirebaseAuthPlugin.SignInCompleteListener
C:\Users\Dell\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:558: error: cannot find symbol
    public void onComplete(@NonNull Task<Void> task) {
                            ^
  symbol:   class NonNull
  location: class FirebaseAuthPlugin.TaskVoidCompleteListener
C:\Users\Dell\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:576: error: cannot find symbol
    public void onComplete(@NonNull Task<ProviderQueryResult> task) {
                            ^
  symbol:   class NonNull
  location: class FirebaseAuthPlugin.ProvidersCompleteListener
C:\Users\Dell\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:175: error: cannot find symbol
                      public void onComplete(@NonNull Task<AuthResult> task) {
                                              ^
  symbol: class NonNull
C:\Users\Dell\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:270: error: cannot find symbol
          public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                                          ^
  symbol: class NonNull
C:\Users\Dell\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:435: error: cannot find symbol
              public void onComplete(@NonNull Task<GetTokenResult> task) {
                                      ^
  symbol: class NonNull
C:\Users\Dell\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:487: error: cannot find symbol
          public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                                          ^
  symbol: class NonNull
Note: C:\Users\Dell\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
8 errors

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':firebase_auth:compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 7s
Running Gradle task 'assembleDebug'...
Running Gradle task 'assembleDebug'... Done                         8.5s
*******************************************************************************************
The Gradle failure may have been because of AndroidX incompatibilities in this Flutter app.
See  .... for more information on the problem and how to fix it.
*******************************************************************************************
Gradle task assembleDebug failed with exit code 1

android/gradle.properties

org.gradle.jvmargs=-Xmx1536M
android.useAndroidX = true
android.enableJetifier = true

android/app/build.gradle

def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion 28

    lintOptions {
        disable 'InvalidPackage'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.example.proapp"
        minSdkVersion 16
        targetSdkVersion 28
        multiDexEnabled true
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

}


apply plugin: 'com.google.gms.google-services'

pubspec.yaml

    name: pro_app
    description: A new Flutter project.

    # 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.
    # Read more about versioning at semver.org.
    version: 1.0.0+1

    environment:
      sdk: ">=2.1.0 <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: ^0.1.2
      sqflite:
      path_provider: any
      intl:
      flutter_svg:
      charts_flutter:
      # firebase
      cloud_firestore:  
      firebase_auth:
      # firebase_core:  

    dev_dependencies:
      flutter_test:
        sdk: flutter
.......

Note: I have already tried to change compileSdkVersion and targetSdkVersion to 27 but then I got app:processdebugresources error.

Answer 1

The issue seems to be caused by AndroidX migration issues. There are two ways to add AndroidX support to the existing project. You can either do the migration via Android Studio or by running flutter create.... If you're still having issues, I suggest running flutter doctor -v to check for any errors and warnings.