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 INSTANCE : AppDatabase? = null

        fun getDatabaseBuilder(context: Context) : AppDatabase{
            if (INSTANCE == null) {
                INSTANCE = Room.databaseBuilder(context.applicationContext, AppDatabase::class.java, "database_app")
                        .allowMainThreadQueries()
                        .build()
            }
            return INSTANCE!!

        }

        fun destroyInstance(){
            INSTANCE = null
        }

    }

}