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 {

    private static AppDatabase INSTANCE;

    public abstract FavoritesDao favoritesDao();

    public static AppDatabase getAppDatabase(Context context) {
        if (INSTANCE == null) {
            INSTANCE =
                    Room.databaseBuilder(context.getApplicationContext(), AppDatabase.class, Constant.DATABASE).allowMainThreadQueries().build();

                    //Room.inMemoryDatabaseBuilder(context.getApplicationContext(),AppDatabase.class).allowMainThreadQueries().build();
        }
        return INSTANCE;
    }

    public static void destroyInstance() {
        INSTANCE = null;
    }
}

Gradle lib:

 compile "android.arch.persistence.room:runtime:+"   
 annotationProcessor "android.arch.persistence.room:compiler:+"

And when i ask for instance it will give this error, AppDatabase_Impl does not exist in my application class

public class APp extends Application {

    private boolean appRunning = false;

    @Override
    public void onCreate() {
        super.onCreate();
        AppDatabase.getAppDatabase(this); //--AppDatabase_Impl does not exist

    }   

}

Caused by: java.lang.RuntimeException: cannot find implementation for AppDatabase. AppDatabase_Impl does not exist — pratik deshai, Oct 10 '17 at 11:59
@pratikdeshai Did you get any solution to this issue? I'm also having the same problem. — Krunal, Jan 03 '18 at 08:53
In my case I removed the kotlin plugin to get it fixed. apply plugin: 'kotlin-kapt' — Napolean, Aug 28 '19 at 05:55

score 481 · Accepted Answer · edited Aug 07 '21 at 14:15

481

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 = "2.3.0" // check latest version from docs

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

UPDATE 2 (since July 2021)

def room_version = "2.3.0" // check latest version from docs

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

edited Aug 07 '21 at 14:15

nayriz

321
1
14

answered Mar 16 '18 at 15:08

RWIL

8,009
1
27
34

2

Thanks a lot. Just moving to Kotlin and all my test cases started failing. Was banging my head. Then I accidentally saw this comment. Saved my day. – Ozeetee Mar 20 '18 at 02:58
89

Also need to add `apply plugin: 'kotlin-kapt'` to the top of the app level `build.gradle` file – daka Jun 06 '18 at 20:12
1

This saved me....I think Google should work more on showing proper error...I had kapt call but I didnt add apply kapt-plugin – anoop4real Dec 24 '18 at 10:51
Was stuck since yesterday. thanks a lot. I don't understand why don't google people mention this in the documentation. – Shubham Anand Sep 21 '19 at 12:08
You're the GOAT saved me with that quick gradle fix – Tonnie Nov 19 '19 at 04:27
Works for me but I'd love to understand why, could you elaborate? – Daniel Jan 12 '20 at 17:13
1

It now has changed to `implementation "androidx.room:room-ktx:$room_version"` – Joe Gasewicz Jul 19 '21 at 17:59
FAILURE: Build failed with an exception. * What went wrong: Execution failed for task ':app:kaptDebugKotlin'. > A failure occurred while executing org.jetbrains.kotlin.gradle.internal.KaptWithoutKotlincTask$KaptExecutionWorkAction > java.lang.reflect.InvocationTargetException (no error message) – Chandler Oct 09 '21 at 11:03
it worked for me – Ali Salehi Feb 11 '22 at 23:52

Jahangir Kabir · Answer 2 · 2018-11-14T04:56:16.633

89

Just use

apply plugin: 'kotlin-kapt'

in app build.gradle

And keep both in dependencies

annotationProcessor "android.arch.persistence.room:compiler:$rootProject.roomVersion"
kapt "android.arch.persistence.room:compiler:$rootProject.roomVersion"

EDIT

In newer version don't need to add both dependencies at a time Just use, hope it will work.

kapt 'android.arch.persistence.room:compiler:1.1.1'

edited Nov 14 '18 at 04:56

answered May 21 '18 at 08:05

Jahangir Kabir

1,663
13
15

score 26 · Answer 3 · answered Apr 18 '18 at 14:37

26

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

answered Apr 18 '18 at 14:37

Thadeus Ajayi

663
7
14

2

For clarity, this goes immediately above the DB class definition. It appears to have fixed my problem - thanks! – winwaed Jun 02 '18 at 02:36
make sure you don't have empty constructors (constructor(){}) in your entities https://stackoverflow.com/a/60494924/6148931 – Martynas B Jan 27 '21 at 12:23
I had this problem and changing the build.gradle as the accepted answer did not solve the problem. Adding this annotation solved the problem, but in [the tutorial I was following](https://developer.android.com/training/data-storage/room#groovy), the "user" class has only `@Entity`, not `@Entity(tablename="table name" )`. If this is required, why does the tutorial lack this annotation? – Damn Vegetables Dec 26 '21 at 00:29

score 21 · Answer 4 · answered Jul 08 '19 at 09:25

21

if you are using kotlin classes to implement database then use

apply plugin: 'kotlin-kapt'

and

kapt "android.arch.persistence.room:compiler:1.1.1"

in your gradle file, it will work.

answered Jul 08 '19 at 09:25

navalkishoreb

513
2
8
16

This works on Android Studio 3.5 (however the current room compiler version is 2.1.0) – Yennefer Sep 10 '19 at 16:40
I think most of the people were not using androidx library in whole project... that why I suggested 1.1.1... I myself faced compilation issues and felt safe with minimal changes using older version. – navalkishoreb Sep 11 '19 at 08:53

score 14 · Answer 5 · answered Nov 07 '18 at 10:10

14

For Kotlin Developers

Use this:

implementation "android.arch.persistence.room:runtime:1.0.0"
kapt "android.arch.persistence.room:compiler:1.0.0"

And add apply plugin: 'kotlin-kapt' to the top of the app level build.gradle.

For Java Developers

implementation "android.arch.persistence.room:runtime:1.0.0"
annotationProcessor "android.arch.persistence.room:compiler:1.0.0"

answered Nov 07 '18 at 10:10

Pedro Massango

3,365
2
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40

Different answers! – Pedro Massango May 14 '20 at 14:24
How come this is different dude? – Patrick Prakash May 15 '20 at 16:18
it's the solution , it helped me to get over the error – Ali Salehi Feb 11 '22 at 23:53

score 11 · Answer 6 · answered Mar 14 '18 at 14:06

It is not just about updating your dependencies. Make sure all your Room dependencies have the same version.

implementation 'android.arch.persistence.room:rxjava2:1.1.0-alpha2'
implementation 'android.arch.persistence.room:runtime:1.1.0-alpha2'
annotationProcessor "android.arch.persistence.room:compiler:1.1.0-alpha2"

In the sample snippet above, all my Room dependencies have the same version 1.1.0-alpha2

score 9 · Answer 7 · answered Nov 10 '18 at 08:06

9

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

answered Nov 10 '18 at 08:06

duyuanchao

3,251
23
15

I forgot it too. Thank you :) But still crashh :( – coinhndp Nov 10 '18 at 12:59
1

Fix by adding kapt – coinhndp Nov 10 '18 at 13:03

score 9 · Answer 8 · answered Jun 11 '19 at 07:53

make sure to add correct dependency for room in build.gradle

ext {
   roomVersion = '2.1.0-alpha06'
}

// Room components
implementation "androidx.room:room-runtime:$rootProject.roomVersion"
implementation "androidx.room:room-ktx:$rootProject.roomVersion"
kapt "androidx.room:room-compiler:$rootProject.roomVersion"
androidTestImplementation "androidx.room:room-testing:$rootProject.roomVersion"

And below line at the top-

apply plugin: 'kotlin-kapt'

score 8 · Answer 9 · answered Jan 24 '18 at 11:09

I met this problem because I have forgotten the apt dependences

implementation "android.arch.lifecycle:extensions:$archLifecycleVersion"
implementation "android.arch.persistence.room:runtime:$archRoomVersion"
annotationProcessor "android.arch.lifecycle:compiler:$archLifecycleVersion"
annotationProcessor "android.arch.persistence.room:compiler:$archRoomVersion"

after added the annotationProcessor, and rebuild it, the problem solved.

Hajo · Answer 10 · 2018-11-23T14:34:27.850

Had the same problem. Implemented the few classes and interface as officially told in a new example project created by Android Studio: https://developer.android.com/training/data-storage/room/

All mentioned solutions above did not help, the necessary _Impl files according to my database class were not generated by Room. Finally executing gradle clean build in terminal gave me the hint that lead to the solution:

"warning: Schema export directory is not provided to the annotation processor so we cannot export the schema. You can either provide room.schemaLocation annotation processor argument OR set exportSchema to false."

I added the parameter exportSchema = false in the database class

@Database(entities = arrayOf(User::class), version = 1, exportSchema = false)
abstract class AppDatabase : RoomDatabase() {
    abstract fun userDao(): UserDao
}

And then it worked, found these two generated files in the app module under generatedJava:

AppDatabase_Impl
UserDao_Impl

I don't understand this behaviour as the parameter is said to be optional, see https://stackoverflow.com/a/44645943/3258117

Running ./gradlew clean build from the terminal was the key. For me I got this message: app: 'annotationProcessor' dependencies won't be recognized as kapt annotation processors. Please change the configuration name to 'kapt' for these artifacts: 'android.arch.lifecycle:compiler:1.1.1' and apply the kapt plugin: "apply plugin: 'kotlin-kapt'". — Randy, Dec 27 '18 at 08:05
Ah yes, executing the tasks in terminal also helped me a lot in the past. The build tools messages in the IDE often "hide" the original error message — Hajo, Dec 29 '18 at 14:03

score 7 · Answer 11 · answered Jun 17 '19 at 17:19

The question is pretty old, but I've stumbled on this today and none of the provided answers helped me. Finally I managed to resolve it by noticing that google documentation actually is still adopted to Java and not Kotlin by default, actually they have added a comment which I've ignored

For Kotlin use kapt instead of annotationProcessor

So, instead of

annotationProcessor "androidx.room:room-compiler:$room_version"

If you are developing with Kotlin, you should use:

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

score 7 · Answer 12 · answered Jul 16 '21 at 17:54

If you are using kotlin, add kotlin annotation processor plugin to app level build.gradle

plugins {
    id "org.jetbrains.kotlin.kapt"
}

Also remove annotationProcessor and replace it with kapt

Instead of

dependencies {
    def room_version = "2.3.0"
    implementation "androidx.room:room-runtime:$room_version"
    annotationProcessor "androidx.room:room-compiler:$room_version"
}

Use

dependencies {
    def room_version = "2.3.0"
    implementation "androidx.room:room-runtime:$room_version"
    kapt "androidx.room:room-compiler:$room_version"
}

The annotationProcessor only works in java environment. The kapt takes care of both java and kotlin. If something wrong with your implementation, those plugins will show them at the compile time.

score 5 · Answer 13 · answered Jan 29 '22 at 22:12

Agreed with the above answers

The solution is as below. Change annotationProcessor to kapt as below

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

score 4 · Answer 14 · answered Mar 19 '20 at 21:05

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.

answered Mar 19 '20 at 21:05

ZakariaBK

555
9
23

score 3 · Answer 15 · edited Nov 16 '21 at 20:04

3

Use the following gradle link:

compile 'android.arch.persistence.room:runtime:1.0.0-alpha9'
annotationProcessor 'android.arch.persistence.room:compiler:1.0.0-alpha9'

You need to create a different singleton class and get the AppDatabase from there like this:

RoomDB.java

public class RoomDB {

private static RoomDB INSTANCE;

public static AppDatabase getInstance(Context context) {
    if (INSTANCE == null) {
        INSTANCE =
                Room.databaseBuilder(context.getApplicationContext(), AppDatabase.class, Constant.DATABASE).allowMainThreadQueries().build();

                //Room.inMemoryDatabaseBuilder(context.getApplicationContext(),AppDatabase.class).allowMainThreadQueries().build();
    }
    return INSTANCE;
}

public static void destroyInstance() {
    INSTANCE = null;
}

App.java

public class App extends Application {

private boolean appRunning = false;

@Override
public void onCreate() {
    super.onCreate();
    RoomDB.getInstance(this); //This will provide AppDatabase Instance
}

edited Nov 16 '21 at 20:04

Amine Karimi

119
11

answered Oct 10 '17 at 11:37

Burhanuddin Rashid

4,992
5
34
51

i didn't create constructor, i am using directly via static instance. – pratik deshai Oct 10 '17 at 11:57
I have created a Sample Project for Room Database you can check it here: https://github.com/burhanrashid52/Android-Room-Data-Persistent – Burhanuddin Rashid Oct 10 '17 at 12:00
2

yes i updated but sill same error, AppDatabase_Impl does not exist – pratik deshai Oct 10 '17 at 13:08
@pratikdeshai: Have you fixed that error ?? I also get same error, get stuck because of this. – Jayesh Jul 04 '18 at 12:09

score 3 · Answer 16 · answered Aug 22 '18 at 20:22

3

In my case, I was testing the connectivity for room database and I have put the testing class inside the directory which I have created inside the AndroidTest folder. I have moved it out of the custom directory, then it worked pretty well.

answered Aug 22 '18 at 20:22

Farruh Habibullaev

2,133
1
23
32

This is my issue too. Any idea why this is happening and how to avoid this? I'd rather prefer not to have a `TestDatabase` in the release code. – Eduardo Sep 17 '18 at 13:06

score 3 · Answer 17 · answered Mar 18 '19 at 16:07

The same phenomenon occurred to me.

following

implementation "android.arch.persistence.room:runtime:1.1.1"

Adding causes another build error but tracks the cause from the log.

In my case, there was an error in the SQL implementation. After fixing, the build was successful.

So you may want to check the implementation of the entire room library instead of looking at the crashed locals.

score 2 · Answer 18 · answered Dec 30 '18 at 07:56

2

The issue is more around the correct library that is not included in the gradle build. I had a similar issue and added the missing

testImplementation "android.arch.persistence.room:testing:$room_version

answered Dec 30 '18 at 07:56

Saurabh Sharma

135
1
8

score 2 · Answer 19 · answered Nov 25 '19 at 06:49

2

Changing the dependencies in my gradle file did'nt help me in fixing the error.I had missed this Database annotation in class where Room database was initialized which was causing this issue.

@Database(entities = [UserModel::class], version = 1)

Ensure that the entity model specified in the annotation above refers to the particular model class

answered Nov 25 '19 at 06:49

Wajhia Maqsood

68
4

this is what i missed – pjwin Dec 05 '19 at 05:26

score 2 · Answer 20 · answered Nov 16 '20 at 10:21

For Kotlin Developers

if you checked Dao and Entity and also used Kapt and there is no problem, I guess there is a problem with your kotlin version if you are using kotlin 1.4 and above. update Room to last version from this link.

2.3.0-alpha03 solved my problem.

score 1 · Answer 21 · answered Jan 09 '20 at 03:07

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.

score 1 · Answer 22 · answered Dec 20 '20 at 14:10

1

In addition to missing

annotationProcessor "android.arch.persistence.room:compiler:x.x.x"

I had also missed adding the below annotation in my class

@Entity(tableName = "mytablename")

answered Dec 20 '20 at 14:10

Meenohara

118
3
8

score 0 · Answer 23 · answered Mar 10 '20 at 22:22

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!

score 0 · Answer 24 · answered Jun 26 '20 at 09:57

Not in the case of OP, but this also happens when you mistakenly use implementation instead of annotationProcessor like this:

implementation "android.arch.persistence.room:compiler:x.x.x"

Instead of this:

annotationProcessor "android.arch.persistence.room:compiler:x.x.x"

score 0 · Answer 25 · answered Feb 25 '21 at 13:09

0

Just in case anyone out there should make the same mistake as I did, don't call your database class "Database" or you'll get the same error.

answered Feb 25 '21 at 13:09

J. O. A. Rayner-Hilles

386
1
13

score 0 · Answer 26 · answered Apr 21 '22 at 15:29

Nothing works from above answers and I noticed that the issue persists for me when I'm using room version2.3.0 or 2.4.2. However, 2.5.0-alpha01 version works well when I applied it.

build.gradle:app

def roomVersion = '2.5.0-alpha01'
implementation "androidx.room:room-ktx:$roomVersion"
kapt "androidx.room:room-compiler:$roomVersion"
testImplementation "android.arch.persistence.room:testing:$roomVersion"

Android room persistent: AppDatabase_Impl does not exist

26 Answers26

UPDATE

UPDATE 2 (since July 2021)

Linked

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