MainActivity.kt

class MainActivity : AppCompatActivity(), ServiceLocatorActivity {

    override val self: Activity = this

    private val mainViewModelFactory: MainViewModelFactory by lazy {
        serviceLocator.mainViewModelFactory
    }

    private val viewModel: MainViewModel by viewModels {
        mainViewModelFactory
    }

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

    private fun observarTextOperacion() {
        viewModel.operacion.observe(this, Observer { expresionOperacion ->
            tvVisualizadorOperacion?.text = expresionOperacion
        })
    }

    private fun configurarClickListener() {
        btnCero?.setOnClickListener { viewModel.onClick(ViewEvent.ClickNumero(Numeros.CERO)) }
    }
}