I am trying to make a copy of the following Java class in Kotlin.
@Database(entities = {Word.class}, version = 1)
public abstract class WordRoomDatabase extends RoomDatabase {
public abstract WordDao wordDao();
private static WordRoomDatabase INSTANCE;
static WordRoomDatabase getDatabase(final Context context) {
if (INSTANCE == null) {
synchronized (WordRoomDatabase.class) {
if (INSTANCE == null) {
INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
WordRoomDatabase.class, "word_database")
.build();
}
}
}
return INSTANCE;
}
}
I am following a tutorial by code labs to implement a simple SQLite data base using Room. Following is my complete Kotlin implementation of the class.
@Database(entities = [Word::class], version = 1)
abstract class WordRoomDatabase : RoomDatabase() {
abstract fun wordDao(): WordDao
private class PopulateDbAsync(db: WordRoomDatabase) : AsyncTask<Unit, Unit, Unit>() {
private val dao = db.wordDao()
override fun doInBackground(vararg params: Unit) {
dao.deleteAll()
var word = Word("Hello")
dao.insert(word)
word = Word("World")
dao.insert(word)
}
}
companion object {
private var INSTANCE: WordRoomDatabase? = null
private val roomDatabaseCallback = object : RoomDatabase.Callback() {
override fun onOpen(db: SupportSQLiteDatabase) {
super.onOpen(db)
PopulateDbAsync(INSTANCE as WordRoomDatabase).execute()
}
}
fun getDatabase(context: Context): WordRoomDatabase {
if (INSTANCE == null) {
synchronized(WordRoomDatabase::class) {
if (INSTANCE == null) {
INSTANCE = Room.databaseBuilder(context.applicationContext,
WordRoomDatabase::class.java, "word_database")
.addCallback(roomDatabaseCallback)
.build()
}
}
}
return INSTANCE as WordRoomDatabase
}
}
}
When I try to access the data inside the companion object I get the following error. cannot find implementation for com.fifthgen.androidroomtest.data.WordRoomDatabase.WordRoomDatabase_Impl does not exist
This is the line of code where the error occurs.
private val db = WordRoomDatabase.getDatabase(application)
