CODEWITHSUNDEEP
androidandroid-room
Harvinder Rathor
Harvinder Rathor

Reputation: 49

Why does Room show me that AppDatabase_Impl does not exist error?

01-17 14:25:21.567 5084-5084/? E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.harv.swat, PID: 5084 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.harv.swat/com.example.harv.swat.HomeActivity}: java.lang.RuntimeException: cannot find implementation for com.example.harv.swat.model.AppDatabase. AppDatabase_Impl does not exist at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2696) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2757) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1504) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:163) at android.app.ActivityThread.main(ActivityThread.java:6237) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:877) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767) Caused by: java.lang.RuntimeException: cannot find implementation for com.example.harv.swat.model.AppDatabase. AppDatabase_Impl does not exist at android.arch.persistence.room.Room.getGeneratedImplementation(Room.java:92) at android.arch.persistence.room.RoomDatabase$Builder.build(RoomDatabase.java:454) at com.example.harv.swat.model.Db.(Db.java:16) at com.example.harv.swat.model.Db.getInstance(Db.java:20) at com.example.harv.swat.HomeActivity.onCreate(HomeActivity.java:28) at android.app.Activity.performCreate(Activity.java:6847) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2649) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2757)  at android.app.ActivityThread.-wrap12(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1504)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:163)  at android.app.ActivityThread.main(ActivityThread.java:6237)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:877)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

public class Db {
AppDatabase adb;
private static Db db;

private Db(Context context){
    adb = Room.databaseBuilder(context,
            AppDatabase.class, "swat").allowMainThreadQueries().build();
}
public static Db getInstance(Context context){
    if(db==null){
        db = new Db(context);
    }
    return db;
}
public MyDAO getDao(){
    return adb.userDao();
}}

DOA class

@Dao
public interface MyDAO {
@Query("SELECT * FROM content")
List<Content> getAll();

@Query("SELECT * FROM content WHERE id IN (:userIds)")
List<Content> loadAllByIds(int[] userIds);

/*@Query("SELECT * FROM user WHERE first_name LIKE :first AND "
        + "last_name LIKE :last LIMIT 1")
Content findByName(String first, String last);*/

@Insert
void insertAll(Content... users);

@Delete
void delete(Content user);}

Gradle file

dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
implementation 'com.android.support:appcompat-v7:26.1.0'
implementation 'com.android.support.constraint:constraint-layout:1.0.2'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.1'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'

// ViewModel and LiveData
implementation "android.arch.lifecycle:extensions:1.0.0"
implementation "android.arch.lifecycle:common-java8:1.0.0"
//annotationProcessor "android.arch.lifecycle:compiler:1.0.0"

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

// Test helpers for Room
testImplementation "android.arch.persistence.room:testing:1.0.0"
}

Upvotes: 3

Views: 11113

Answers (3)

Oleksii Kolotylenko
Oleksii Kolotylenko

Reputation: 1090

The question was asked a long time ago, but in 2024, it has become relevant again with the use of Kotlin Multiplatform. The following line in the Gradle file of the Compose project was a stumbling block for me.

dependencies {
    add("kspAndroid", libs.androidx.room.compiler) // Add this line
}

Where

    androidx-room-compiler = { module = "androidx.room:room-compiler", version.ref = "roomVer" }

This block needs to be placed at the root of the Gradle file, on the same level as the plugins or kotlin blocks.

Currently, projects using KMP can have different Gradle file and directory structures. This solution is applicable to projects with the following structure:

enter image description here

Upvotes: 1

Tonnie
Tonnie

Reputation: 8102

Had the same error and the reason for this is missing this line:

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

You need to annotate your ROOM database class with @Database annotation and also pass in your tables and version.

@Database(entities = [YourEntityClass::class], version = 1)
abstract class YourDatabase : RoomDatabase(){}

Upvotes: 1

Andrew Steinmetz
Andrew Steinmetz

Reputation: 1049

It could be possible that the file wasn't regenerated when changes were made. Perhaps try rebuilding the project: Build -> Rebuild

Upvotes: 1

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