Android room persistent: AppDatabase_Impl不存在

我的app数据库类

@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自由:

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

当我请求实例时，它会给出这个错误，AppDatabase_Impl不存在在我的应用课上

public class APp extends Application {

    private boolean appRunning = false;

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

    }   

}

当前回答

在OP的情况下不是这样，但是当你错误地使用implementation而不是annotationProcessor时也会发生这种情况，就像这样:

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

而不是这样:

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

2020-06-26 09:57:07

其他回答

如果您正在使用kotlin类来实现数据库，那么使用

apply plugin: 'kotlin-kapt'

and

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

在您的gradle文件中，它将工作。

2019-07-08 09:25:36

检查类上面的注释

@Database(entities = arrayOf(Schedule::class), version = 1)
abstract class AppDatabase : RoomDatabase() {
// ....
}

2022-08-16 06:24:51

使用下面的gradle链接:

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

你需要创建一个不同的单例类，并从那里获取AppDatabase，如下所示:

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
}

2017-10-10 11:37:43

除了思念

annotationProcessor“android.arch.persistence.room:编译器:. x.x.x”

我还错过了在课上添加下面的注释

@Entity(tableName = "mytablename")

2020-12-20 14:10:21

同意以上回答

解决方法如下。如下所示，将annotationProcessor更改为kapt

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

2022-01-29 22:12:32

Android room persistent: AppDatabase_Impl不存在

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