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

Question

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"
}

Have you extended AppDatabase with RoomDatabase? – Sonu Sanjeev Jan 17 '18 at 11:32 — Sonu Sanjeev, Jan 17 '18 at 11:32
Did you get any solution for this one? – xrnd Jan 19 '18 at 11:00 — xrnd, Jan 19 '18 at 11:00

score 1 · Answer 1 · answered Jan 17 '18 at 09:40

1

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

answered Jan 17 '18 at 09:40

Andrew Steinmetz

1,010
8
16

score 1 · Answer 2 · answered Jun 10 '22 at 07:18

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(){}

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

2 Answers2