Automigration annotation ERROR in Room with Java - android-studio

Question

inserting a new (BLOB) field, i modified schema of my room database in Android Studio.
After that i had to increment database version, too. I also added
#Database(
version = 2,
entities = [
Table1.class,
Table2.class
],
autoMigrations = [
#AutoMigration (
from = 1,
to = 2
),
...
in the #Database annotation. Now i get the error "cannot resolve symbol #automigration" in the logcat and do not find a hint to solution.
Thanks in advance.
EDIT, full class:
#Database(entities = {Device.class, User.class,
DeviceUserCrossRef.class},
autoMigrations = {
#AutoMigration (from = 1, to =2)
}
,exportSchema = true,
version = 2)
#TypeConverters({DateConverter.class, ImageConverter.class})
public abstract class DeviceDatabase extends RoomDatabase {
private static DeviceDatabase INSTANCE;
// Getter pro DAO
public abstract DeviceDao deviceDao();
public abstract UserDao userDao();
public abstract UserWithDevicesDao userWithDevicesDao();
public abstract DeviceWithUsersDao deviceWithUsersDao();
// Entwurfsmuster Singleton
// Nur eine Instanz der Klasse darf erstellt werden
public static DeviceDatabase getInstance(Context context) {
// Haben wir schon eine Instanz erstellt
if (INSTANCE == null) {
// Sperre für andere Threads
synchronized (DeviceDatabase.class) {
if (INSTANCE == null) {
// Nein, es gibt noch keine Instanz
// -> eine neue Instanz erzeugen
INSTANCE = Room.databaseBuilder(
context.getApplicationContext(),
DeviceDatabase.class,
"database.sqlite"
).build();
}
}
}
return INSTANCE;
}
}
EDIT 2:
EDIT 3:

Answer 1

I believe that your issue is that you are mixing Java and Kotlin code.
In Kotlin a list of items can be specified within square brackets [ .... and ] e.g. you have:-
entities = [Table1.class,Table2.class]
and
autoMigrations = [#AutoMigration (from = 1,to = 2)
i.e. lists according to Kotlin.
However Table1.java, Tbale2.java and #AutomMigration are coded as Java items.
So you for Kotlin you should use:-
#Database(
entities = [Table1::class,Table2::class],
autoMigrations = [ AutoMigration(from = 1, to = 2)],
exportSchema = true,
version = 2
)
or for Java you should use :-
#Database(
entities = {Table1.class,Table2.class},
autoMigrations = {
#AutoMigration(from = 1, to =2)
}
,exportSchema = true,
version = 2
)
Example/Demo
The following demonstrates using Kotlin:-
#Entity
data class Table1(
#PrimaryKey
val table1Id: Long?=null,
val table1Name: String
,#ColumnInfo(defaultValue = "FFX") val table1Blob: ByteArray /*<<<<<<<<<< ADDED for V2 */
)
#Entity class Table2(
#PrimaryKey
val table2Id: Long?=null,
val table2Name: String
)
#Dao
interface TheDaoInterface {
#Insert
fun insert(table1: Table1): Long
#Insert
fun insert(table2: Table2): Long
}
#Database(
entities = [Table1::class,Table2::class],
autoMigrations = [ AutoMigration(from = 1, to = 2)/*<<<<<<<<<< ADDED FOR V2 */],
exportSchema = true,
version = /*1*/ 2 /*<<<<<<<<<< CHANGED FOR V2 */
)
abstract class TheDatabase: RoomDatabase() {
abstract fun getTheDaoInterface(): TheDaoInterface
companion object {
private var instance: TheDatabase?=null
fun getInstance(context: Context): TheDatabase {
if (instance==null) {
instance = Room.databaseBuilder(context,TheDatabase::class.java,"the_database.db")
.allowMainThreadQueries()
.build()
}
return instance as TheDatabase
}
}
}
With the resultant database being:-
and using Java
#Entity
class Table1 {
#PrimaryKey
Long table1Id=null;
String table2Name;
byte[] table1Blob; /*<<<<<<<<<< ADDED FOR V2 */
}
#Entity
class Table2 {
#PrimaryKey
Long table2Id=null;
String table2Name;
}
#Database(
entities = {Table1.class,Table2.class},
autoMigrations = {
#AutoMigration(from = 1, to =2)
}
,exportSchema = true,
version = 2
)
abstract class TheDatabase extends RoomDatabase {
abstract TheDao getTheDao();
private static volatile TheDatabase instance;
static TheDatabase getInstance(Context context) {
if (instance==null) {
instance = Room.databaseBuilder(context,TheDatabase.class,"the_database.db")
.allowMainThreadQueries()
.build();
}
return instance;
}
}
The identity hashes (hash based upon the schema) clearly showing two different database (i.e. Kotlin V Java)