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I updated my build and target version to 28 (Pie) and replaced the relevant dependencies. Now my project says Symbol not found on AppCompatActivity. I have tried to

• Clean project


• Rebuild project


• Invalidate Caches / Restart

But the result is the same. Moreover when I try Ctrl+Space after extends keyword in activity class there is no "AppCompatActivity suggestion. I tried to investigate if its present in libraries folder, it's present there.

Now, what should I do to make it work? If there is any variation/alternative with androidx libs please let me know. Here is my complete build.gradle file

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

android 
 compileSdkVersion 28
 defaultConfig 
 applicationId "com.invogen.messagingapp"
 minSdkVersion 16
 targetSdkVersion 28
 versionCode 1
 versionName "1.0"
 testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
 
 buildTypes 
 release 
 minifyEnabled false
 proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
 
 


dependencies 
 implementation fileTree(dir: 'libs', include: ['*.jar'])
// implementation 'com.android.support:appcompat-v7:28.0.0'
// implementation 'com.android.support.constraint:constraint-layout:1.1.3'
// implementation 'com.android.support:design:28.0.0'
// implementation 'com.android.support:support-v4:28.0.0'

 // Libs for newer API 28
 implementation 'androidx.appcompat:appcompat:1.0.2'
 implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
 implementation 'com.google.android.material:material:1.1.0-alpha01'
 implementation 'androidx.cardview:cardview:1.0.0'


 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'

 // Libs for Firebase Functionality
 implementation 'com.google.firebase:firebase-core:16.0.5'
// implementation 'com.google.firebase:firebase-database:16.0.4'
 implementation 'com.google.firebase:firebase-messaging:17.3.4'
 implementation 'com.google.firebase:firebase-auth:16.0.5'
 implementation 'com.google.firebase:firebase-storage:16.0.4'

 // Lib for Firebase UI Elements
 implementation 'com.firebaseui:firebase-ui-database:4.2.1'

 // Libs for QR Code
 implementation 'com.google.zxing:core:3.2.1'
 implementation 'com.journeyapps:zxing-android-embedded:3.2.0@aar'

 // Lib for Circle Image View (Profile Image)
 implementation 'de.hdodenhof:circleimageview:2.2.0'

 // Lib for Loading Images
 implementation 'com.squareup.picasso:picasso:2.71828'

 //Lib for Cropping Images
 api 'com.theartofdev.edmodo:android-image-cropper:2.8.+'



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

Some other posts suggest adding the below two parameters in Manifest file

android:appComponentFactory="anystrings be placeholder"
tools:replace="android:appComponentFactory"

But with these two lines project sync with multiple error and Android Studio says

Compilation failed; see the compiler error output for details.

If I have to add more detail to the question please let me know.

With Clean and build and Rebuild project android studio did not clean the unused imports like imports from android.support.v7 so I removed them all manually from all activities. Now android studio suggests AppCompatActivity from the correct library.

Hope so it will help someone.

you should replace the target class.

eg.

import android.support.v7.app.AppCompatActivity;

replace to :

import androidx.appcompat.app.AppCompatActivity;