title: With API 28 and "androidx.appcompat" library project says "AppCompatActivity" symbol not found
body: <p>I updated my build and target version to 28 (Pie) and replaced the relevant dependencies. Now my project says Symbol not found on <code>AppCompatActivity</code>. I have tried to </p>
  
  <ul>
  <li>Clean project</li>
  <li>Rebuild project</li>
  <li>Invalidate Caches / Restart</li>
  </ul>
  
  <p>But the result is the same. Moreover when I try <kbd>Ctrl</kbd>+<kbd>Space</kbd> after extends keyword in activity class there is no <code>"AppCompatActivity</code> suggestion. I tried to investigate if its present in <code>libraries</code> folder, it's present there.</p>
  
  <p><a href="https://i.stack.imgur.com/h0iTb.png" rel="noreferrer"><img src="https://i.stack.imgur.com/h0iTb.png" alt="enter image description here"></a></p>
  
  <p>Now, what should I do to make it work? If there is any variation/alternative with <code>androidx</code> libs please let me know. Here is my complete <code>build.gradle</code> file</p>
  
  <pre><code>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'
  </code></pre>
  
  <p>Some other posts suggest adding the below two parameters in <code>Manifest</code> file</p>
  
  <pre><code>android:appComponentFactory="anystrings be placeholder"
  tools:replace="android:appComponentFactory"
  </code></pre>
  
  <p>But with these two lines project sync with multiple error and Android Studio says </p>
  
  <blockquote>
    <p>Compilation failed; see the compiler error output for details.</p>
  </blockquote>
  
  <p>If I have to add more detail to the question please let me know.</p>