Room cannot find implementation

Question

I have a problem with testing a Room database: when I run the test, I get this exception:

java.lang.RuntimeException: cannot find implementation for database.TicketDatabase. TicketDatabase_Impl does not exist
at android.arch.persistence.room.Room.getGeneratedImplementation(Room.java:92)
at android.arch.persistence.room.RoomDatabase$Builder.build(RoomDatabase.java:454)
at com.sw.ing.gestionescontrini.DatabaseTest.setDatabase(DatabaseTest.java:36)
at java.lang.reflect.Method.invoke(Native Method)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:59)
at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:262)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1886)

Class DatabaseTest:

public class DatabaseTest {

    TicketDatabase database;
    DAO ticketDAO;


    @Before
    public void setDatabase() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        Context context = InstrumentationRegistry.getTargetContext();
        database = Room.inMemoryDatabaseBuilder(context, TicketDatabase.class).build();

        Method method = TicketDatabase.class.getDeclaredMethod("ticketDao()");
        method.setAccessible(true);
        ticketDAO = (DAO) method.invoke(database, null);
    }
}

gradle file:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    buildToolsVersion '26.0.2'
    defaultConfig {
        applicationId "com.sw.ing.gestionescontrini"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    defaultConfig {
        multiDexEnabled true
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:26.+'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'

    annotationProcessor 'android.arch.lifecycle:compiler:1.0.0'
    compile 'android.arch.persistence.room:rxjava2:1.0.0-rc1'
    testCompile'android.arch.persistence.room:testing:1.0.0-rc1'

}

I don't really know what this implementation should be, I searched for a solution but all I found doesn't work for me. For instance, many found a solution adding kapt "android.arch.persistence.room..." but gradle doesn't recognize "kapt".

I am having the same issue. The accepted answer does not work for me. Please help if you found a solution. Below is dependency : compile 'android.arch.persistence.room:runtime:1.1.0' annotationProcessor 'android.arch.persistence.room:compiler:1.1.0' compile 'android.arch.persistence.room:rxjava2:1.1.0' — Vishu Bhardwaj, Jun 14 '18 at 08:41
@VishuBhardwaj Check you have an annotation for the Database above the database class like this: `@Database(entities = {Entities.class}, version = 1, exportSchema = true)` — nicklocicero, Jul 06 '18 at 04:25

score 102 · Accepted Answer · edited Jul 29 '19 at 02:18

102

kapt is for Kotlin.

First, add:

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

to your dependencies closure.

Then, upgrade android.arch.persistence.room:rxjava2 and android.arch.persistence.room:testing to 1.0.0 instead of 1.0.0-rc1.

ref: https://developer.android.com/jetpack/androidx/releases/room

edited Jul 29 '19 at 02:18

lasec0203

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answered Nov 13 '17 at 22:40

CommonsWare

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6

to change as kapt instead of annotationProcessor worked for me – Olkunmustafa Jun 18 '18 at 15:25
31

Don't forget to put `apply plugin: 'kotlin-kapt'` in top of your `build.gradle` if you use `kapt`. :) – Abed Naseri Oct 19 '18 at 10:15
I'm not sure how this answer worked for OP since he doesn't appear to be using Kotlin... – Big McLargeHuge Feb 26 '19 at 17:34
@DavidKennedy: The solution here is for a non-Kotlin environment. My first sentence is in reference to the last sentence of the question, where the OP attempted to use `kapt`. – CommonsWare Feb 26 '19 at 23:32
@AbedNaseri I'm going to kiss you. – Bill Mote Apr 22 '20 at 03:36
6

now it's `kapt "androidx.room:room-compiler:$rootProject.roomVersion"` – Raymond Chenon Sep 29 '20 at 13:37

score 53 · Answer 2 · edited Jul 29 '19 at 04:24

53

for Kotlin change the 'annotationProcessor' keyword to 'kapt' in gradle file.

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

and also add on top of the dependency file

apply plugin: 'kotlin-kapt'

ref: https://developer.android.com/jetpack/androidx/releases/room

edited Jul 29 '19 at 04:24

lasec0203

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answered Nov 13 '18 at 21:35

Manzur Alahi

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Iker Solozabal · Answer 3 · 2023-02-15T17:32:04.253

java.lang.RuntimeException: cannot find implementation for com.example.kermovie.data.repository.local.MoviesDatabase. MoviesDatabase_Impl does not exist

You have to add the following code to your build.gradle:

apply plugin: 'kotlin-kapt' 

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

You may have to change room_version variable when a newer version is available.

You can check for a newer version on the following web mvnrepository.com

score 30 · Answer 4 · edited Jul 29 '19 at 02:22

30

If You Use Kotlin sure exists this code in your in grade file.

apply plugin: "kotlin-kapt"

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

Documentation: https://developer.android.com/jetpack/androidx/releases/room

edited Jul 29 '19 at 02:22

atymic

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answered Jan 04 '19 at 10:06

Hossein Hajizadeh

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Grigore Madalin · Answer 5 · 2018-10-25T11:46:05.433

I see some people around here (Vishu Bhardwaj and others on similar StackOverflow questions) complains the accepted answer does not work for them. I think it deserve mentioning I had a similar problem in a MULTI modules project that needed a trick around the accepted answer.

In my multi modules project the room database dependencies where included mostly in one basic module and exported using proper api notation but room code was split along 2 different modules. Project compiled with no warning but java.lang.RuntimeException: cannot find implementation for database... was raised on run-time.

This was fixed by adding

annotationProcessor "android.arch.persistence.room:compiler:$room_version"

in ALL modules that included Room related code.

Razz · Answer 6 · 2021-06-04T08:10:40.527

6

Add this in your app module's buld.gradle file

    //The Room persistence library provides an abstraction layer over SQLite
    def room_version = "2.3.0"
    implementation("androidx.room:room-runtime:$room_version")
    annotationProcessor "androidx.room:room-compiler:$room_version"

In your data access object file add the follwoing annotation

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

Replace entity class name and database version code as per your project need.

If you are using kotlin, apply kapt plugin to the annotation processor as following line:

apply plugin: 'kotlin-kapt'

Then Replace annotationProcessor "androidx.room:room-compiler:$room_version" with the following line:

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

edited Jun 04 '21 at 08:10

answered Jun 04 '21 at 07:55

Razz

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If you are using Data Binding: – Razz Jun 04 '21 at 08:06
1

Works for me. My build.gradle(:app) plugins: id 'com.android.application' id 'org.jetbrains.kotlin.android' id 'kotlin-kapt' dependencies: implementation "androidx.room:room-ktx:2.4.0-rc01" kapt "androidx.room:room-compiler:2.4.0-rc01" – dobhareach Feb 04 '22 at 10:14

score 4 · Answer 7 · answered Dec 07 '18 at 12:49

This gradle works nicely. Notice the plugin kotlin-kapt at the beggining. It's crucial.

apply plugin: 'kotlin-kapt'
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "????"
        minSdkVersion 21
        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"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    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'

    implementation 'android.arch.persistence.room:runtime:1.1.1'
    kapt 'android.arch.persistence.room:compiler:1.1.1'
}

Thanks, @Ráfagan. The line apply plugin: 'kotlin-kapt' made my day :) — David Burgos Prieto, Jan 23 '19 at 11:22

Wajid · Answer 8 · 2019-02-04T10:09:58.763

3

I did as everybody said in above answer still no luck.
The issue on my end was that, I was doing insertion on main thread.

roomDatabase = Room.databaseBuilder(DexApplication.getInstance(),MyRoomDatabase.class,"db_name")
                    .fallbackToDestructiveMigration() // this is only for testing, 
                       //migration will be added for release
                    .allowMainThreadQueries() // this solved the issue but remember that its For testing purpose only
                    .build();

Explanation:

.allowMainThreadQueries()

allows you run queries on the main thread. But keep in mind to remove it and implement, RxJava, Live Data or any other background process mechanism for querying database. Hope that would help.

edited Feb 04 '19 at 10:09

answered Jan 11 '19 at 11:36

Wajid

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You did this `.fallbackToDestructiveMigration() // this is only for testing` but forgot to `.allowMainThreadQueries() // this also is only for testing.` Never allow main thread queries on production applications. – Naveen Niraula Feb 03 '19 at 10:25
@NaveenNiraula edited the answer, thanks for suggestion. – Wajid Feb 04 '19 at 10:11

score 3 · Answer 9 · answered Apr 08 '19 at 17:22

3

Add below plugin and dependency

apply plugin: 'kotlin-kapt'

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

answered Apr 08 '19 at 17:22

Ashutosh Srivastava

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score 3 · Answer 10 · edited Sep 20 '19 at 10:06

3

I will add complete answer that solved my problem

First add all the room dependency of android x second add apply plugin: 'kotlin-kapt' and replace annotationProcessor of room compiler with kept

edited Sep 20 '19 at 10:06

Dharman

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answered Sep 20 '19 at 08:24

blackHawk

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score 3 · Answer 11 · answered Nov 26 '21 at 19:59

I had the same problem. This happens when you forget to add the compiler dependency.

Add these dependencies

    def room = "2.3.0"
    implementation "androidx.room:room-runtime:$room"
    implementation "androidx.room:room-ktx:$room"
    kapt "androidx.room:room-compiler:$room"

score 2 · Answer 12 · answered Feb 14 '20 at 05:55

I'm coming a little bit late but I had the same issue but none of the answers helped me. So I hope my experience will help others. Room couldn't find the implementation while executing my instrumentation tests so adding below line to my gradle file fixed the problem

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

If you use annotation processors for your androidTest or test sources, the respective kapt configurations are named kaptAndroidTest and kaptTest

score 2 · Answer 13 · answered Mar 18 '20 at 03:46

2

In my case, adding the following annotation above the database class solves the problem.

@Database(entities = {Entities.class}, version = 1, exportSchema = false)
public abstract class TheDatabase extends RoomDatabase {...}

Thanks to @nicklocicero.

answered Mar 18 '20 at 03:46

KikiYu

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Jayant Kumar · Answer 14 · 2021-04-12T16:29:06.293

1

it means your room runtime dependency is missing .. please add below dependency in your build.gradle(module) file. This will resolve your issue :)

 dependencies{

     def room_version = "2.2.6"
        implementation "androidx.room:room-ktx:$room_version"
        implementation "androidx.room:room-runtime:$room_version"
        kapt "androidx.room:room-compiler:$room_version"  
}

edited Apr 12 '21 at 16:29

answered Apr 12 '21 at 13:31

Jayant Kumar

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score 1 · Answer 15 · answered Jun 12 '23 at 19:14

I was using KSP and it turned out that the KSP and kotlin versions are incompatible with each other. I upgraded the ksp plugin version to 1.8.21-1.0.11 and it fixed my problem.

in the project-level gradle:

plugins {
    id 'com.google.devtools.ksp' version '1.8.21-1.0.11' apply false
}

In the app level gradle:

plugins {
    id 'com.google.devtools.ksp'
}

You might have to update jvm to 17 as well.

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_17
        targetCompatibility JavaVersion.VERSION_17
    }
    kotlinOptions {
        jvmTarget = '17'
    }

There is a related issue on the KSP repo as well https://github.com/google/ksp/issues/1347

Pilot_51 · Answer 16 · 2022-01-11T15:59:49.557

In my case, I was doing a complete rewrite alongside old code and put the new code in a temporary package called new without thinking it might conflict with the Java keyword. Evidently the Room compiler just ignores packages with that name without giving warnings. Android Studio doesn't warn when creating a new package, but it does say "not a valid package name" when entered in the rename dialog even though it still allows renaming to that. I renamed the package to redesign and no longer had the issue.

Muzamîl Abd Allha · Answer 17 · 2022-11-01T08:05:10.840

0

add this

@Database(entities = [Entity::class], version = 1) to your db class

edited Nov 01 '22 at 08:05

answered Oct 27 '22 at 10:59

Muzamîl Abd Allha

1
2

Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Nov 01 '22 at 02:17

Room cannot find implementation

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