AppDatabase.kt

@Database(entities = arrayOf(Team::class, Player::class), version = 1)
abstract class AppDatabase : RoomDatabase() {

    abstract fun teamDao() : TeamDao
    abstract fun playerDao() : PlayerDao

    companion object {
        var MY_INSTANCE : AppDatabase? = null


        fun createInmemoryDatabse(context : Context) : AppDatabase{
            if (MY_INSTANCE == null){
                MY_INSTANCE = Room.inMemoryDatabaseBuilder(context.applicationContext, AppDatabase::class.java)
                        .allowMainThreadQueries()
                        .build()
            }
            return MY_INSTANCE!!
        }

        fun destroyInstance(){
            MY_INSTANCE = null
        }
    }
}