MainActivity.kt

class MainActivity : AppCompatActivity() {

    lateinit var adapter: RvAdapter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

				// I will tell about ItemStorage in a minute
        adapter = RvAdapter(this, ItemStorage.list) 
        rv.adapter = adapter
        rv.layoutManager = LinearLayoutManager(this)
    }
}