add the dependency in your build.gradle.
def room_version = "2.2.5"
implementation "android.arch.lifecycle:extensions:1.1.0"
implementation "androidx.room:room-runtime:$room_version"
implementation "androidx.room:room-rxjava2:$room_version"
implementation "androidx.room:room-guava:$room_version"
// ViewModel
implementation "androidx.lifecycle:lifecycle-viewmodel:2.3.1"
// LiveData
implementation "androidx.lifecycle:lifecycle-livedata:2.3.1"
annotationProcessor "androidx.room:room-compiler:$room_version"
testImplementation "androidx.room:room-testing:$room_version"