AndroidX not working

[kenonnaidoo]

I have added the imports and dependencies

import android.Manifest;
import android.content.pm.PackageManager;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.appcompat.app.AppCompatActivity;

and

implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.core:core:1.1.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
implementation 'androidx.legacy:legacy-support-v4:1.0.0'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.1'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

But I'm still getting these errors when trying to build the release:

C:\Users...\Desktop\flutter.pub-cache\hosted\pub.dartlang.org\flute_music_player-0.0.6\android\src\main\java\com\mtechviral\musicfinder\MusicHelper.java:8: error: package androidx.core.app does not exist
import androidx.core.app.ActivityCompat;
^
C:\Users...\Desktop\flutter.pub-cache\hosted\pub.dartlang.org\flute_music_player-0.0.6\android\src\main\java\com\mtechviral\musicfinder\MusicHelper.java:9: error: package androidx.core.content does not exist
import androidx.core.content.ContextCompat;
^
C:\Users...\Desktop\flutter.pub-cache\hosted\pub.dartlang.org\flute_music_player-0.0.6\android\src\main\java\com\mtechviral\musicfinder\MusicHelper.java:10: error: package androidx.appcompat.app does not exist
import androidx.appcompat.app.AppCompatActivity;
^
C:\Users...\Desktop\flutter.pub-cache\hosted\pub.dartlang.org\flute_music_player-0.0.6\android\src\main\java\com\mtechviral\musicfinder\MusicHelper.java:15: error: cannot find symbol
public static boolean hasExternalStorageAccess(AppCompatActivity activity) {
^
symbol: class AppCompatActivity
location: class MusicHelper
C:\Users...\Desktop\flutter.pub-cache\hosted\pub.dartlang.org\flute_music_player-0.0.6\android\src\main\java\com\mtechviral\musicfinder\MusicHelper.java:16: error: cannot find symbol
if(ContextCompat.checkSelfPermission(activity, Manifest.permission.READ_EXTERNAL_STORAGE)
^
symbol: variable ContextCompat
location: class MusicHelper
C:\Users...\Desktop\flutter.pub-cache\hosted\pub.dartlang.org\flute_music_player-0.0.6\android\src\main\java\com\mtechviral\musicfinder\MusicHelper.java:19: error: cannot find symbol
ActivityCompat.requestPermissions(activity,
^
symbol: variable ActivityCompat
location: class MusicHelper
Note: C:\Users...Desktop\flutter.pub-cache\hosted\pub.dartlang.org\flute_music_player-0.0.6\android\src\main\java\com\mtechviral\musicfinder\MusicFinderPlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: C:\Users...\Desktop\flutter.pub-cache\hosted\pub.dartlang.org\flute_music_player-0.0.6\android\src\main\java\com\mtechviral\musicfinder\MusicFinderPlugin.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
6 errors

FAILURE: Build failed with an exception.

• What went wrong:
  Execution failed for task ':compileReleaseJavaWithJavac'.

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.

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

BUILD FAILED in 1m 32s

The plugin flute_music_player could not be built due to the issue above.