Viewmodel configuration change

class MainActivity : AppCompatActivity() {
    private val adapter = MovieCardAdapter()
    private lateinit var viewModel: MainViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        // Create/retrieve viewmodel and observe data needed for recyclerview adapter
        viewModel = ViewModelProvider(this).get(MainViewModel::class.java)
        viewModel.movies.observe(this, {
            adapter.items = it
        })

        // Set recyclerview adapter
        binding.cardstackMovies.adapter = adapter

        // If viewmodel has no data for recyclerview adapter, retrieve it
        if (viewModel.movies.value == null) viewModel.retrieveMovies()
    }
}