Because a Kotlin object
can’t have any constructor, you can’t pass any argument to it.
So look at this code from Google’s architecture components sample code, which uses the also
function:
class UsersDatabase : RoomDatabase() {
companion object {
@Volatile private var INSTANCE: UsersDatabase? = null
fun getInstance(context: Context): UsersDatabase =
INSTANCE ?: synchronized(this) {
INSTANCE ?: buildDatabase(context).also { INSTANCE = it }
}
private fun buildDatabase(context: Context) =
Room.databaseBuilder(context.applicationContext,
UsersDatabase::class.java, "Sample.db")
.build()
}
}