override fun onCreate()

in app/src/main/java/com/example/android/uamp/MainActivity.kt [41:88]
25 lines of code
2 McCabe index (conditional complexity)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // Initialize the Cast context. This is required so that the media route button can be
        // created in the AppBar
        castContext = CastContext.getSharedInstance(this)

        setContentView(R.layout.activity_main)

        // Since UAMP is a music player, the volume controls should adjust the music volume while
        // in the app.
        volumeControlStream = AudioManager.STREAM_MUSIC

        /**
         * Observe [MainActivityViewModel.navigateToFragment] for [Event]s that request a
         * fragment swap.
         */
        viewModel.navigateToFragment.observe(this, Observer {
            it?.getContentIfNotHandled()?.let { fragmentRequest ->
                val transaction = supportFragmentManager.beginTransaction()
                transaction.replace(
                    R.id.fragmentContainer, fragmentRequest.fragment, fragmentRequest.tag
                )
                if (fragmentRequest.backStack) transaction.addToBackStack(null)
                transaction.commit()
            }
        })

        /**
         * Observe changes to the [MainActivityViewModel.rootMediaId]. When the app starts,
         * and the UI connects to [MusicService], this will be updated and the app will show
         * the initial list of media items.
         */
        viewModel.rootMediaId.observe(this,
            Observer<String> { rootMediaId ->
                rootMediaId?.let { navigateToMediaItem(it) }
            })

        /**
         * Observe [MainActivityViewModel.navigateToMediaItem] for [Event]s indicating
         * the user has requested to browse to a different [MediaItemData].
         */
        viewModel.navigateToMediaItem.observe(this, Observer {
            it?.getContentIfNotHandled()?.let { mediaId ->
                navigateToMediaItem(mediaId)
            }
        })
    }