Android room persistent: AppDatabase_Impl does not exist

Question

My app database class

@Database(entities = {Detail.class}, version = Constant.DATABASE_VERSION)
public abstract class AppDatabase extends RoomDatabase {

            


        

Answer 1

For me, the Android Studio automatically updated dependencies as soon as you include any of the Room database related imports. But as per https://developer.android.com/jetpack/androidx/releases/room#declaring_dependencies you need to update few. Here is how my code-base looks like:

AppDatabase.kt

import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase

@Database(entities = arrayOf(MyEntity::class), version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun myDAO(): MyDAO

    companion object {
        @Volatile private var instance: AppDatabase? = null
        private val LOCK = Any()

        operator fun invoke(context: Context)= instance ?: synchronized(LOCK){
            instance ?: buildDatabase(context).also { instance = it}
        }

        private fun buildDatabase(context: Context) = Room.databaseBuilder(context,
            AppDatabase::class.java, "db-name.db")
            .build()
    }
}

Update the build.gradle as specified in one of the answers:

apply plugin: 'kotlin-kapt' // this goes with other declared plugin at top
dependencies { // add/update the following in dependencies section
    implementation 'androidx.room:room-runtime:2.2.3'
//    annotationProcessor 'androidx.room:room-compiler:2.2.3' // remove this and use the following
    kapt "androidx.room:room-compiler:2.2.3"

}

Sync the gradle and you should be good to go.

Answer 2

I meet with the problem, because I forget @Dao annotation

@Dao
public interface SearchHistoryDao {
    @Query("SELECT * FROM search_history")
    List<SearchHistory> getAll();

    @Insert
    void insertAll(SearchHistory... histories);

    @Delete()
    void delete(SearchHistory history);
}

Room Official tutorial

Answer 3

Reading the example here: Room Example

I fixed this error just using the correct (I guess it is) annotationProcessorFile, as follows:

annotationProcessor "android.arch.persistence.room:compiler:<latest_version>"

Also, I upgraded to 2.2.0 either in Room Version as in Lifecycle version.

Once synchronized the graddle, I could start working with Room.

So, Good luck! And let the code be with you!

Answer 4

In my kotlin app, I just added the following line at the top of my build.gradle file :

apply plugin: 'kotlin-kapt'

And the following line in the dependencies section:

kapt "androidx.room:room-compiler:2.2.5"

I hope it fixes your issue.

Answer 5

For those working with Kotlin, try changing annotationProcessor to kapt in the apps build.gradle

for example:

// Extensions = ViewModel + LiveData
implementation "android.arch.lifecycle:extensions:1.1.0"
kapt "android.arch.lifecycle:compiler:1.1.0"
// Room
implementation "android.arch.persistence.room:runtime:1.0.0"
kapt "android.arch.persistence.room:compiler:1.0.0"

also remember to add this plugin

apply plugin: 'kotlin-kapt'

to the top of the app level build.gradle file and do a clean and rebuild (according to https://codelabs.developers.google.com/codelabs/android-room-with-a-view/#6)

In Android Studio, if you get errors when you paste code or during the build process, select Build >Clean Project. Then select Build > Rebuild Project, and then build again.

---

UPDATE

If you have migrated to androidx

def room_version = "2.2.3" // check latest version from docs

implementation "androidx.room:room-runtime:$room_version"
kapt "androidx.room:room-compiler:$room_version"

Answer 6

I had this error when I missed

@Database(entity="{<model.class>})

Ensure that the entity model specified in the annotation above refers to the particular model class and also ensure that the necessary annotation:

@Entity(tableName = "<table_name>" ...)

is properly defined and you'd be good