How to implement a BaseActivity in mvvm architecture? Without using dependency Injection

Question

I am currently learning MVVM architecture,

I tried to make a BaseActivity class.

My BaseActivity:-

abstract class BaseActivity<ViewModel : BaseViewModel, Binding : ViewDataBinding> :
    AppCompatActivity(),
    EventListener {

    
    lateinit var binding: Binding
    private var viewModel: ViewModel? = null


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

        binding = DataBindingUtil.setContentView(this, layoutid)
        this.viewModel = viewModel ?: getViewModel()
        binding.setVariable(getBindingVariable(), viewModel)
        binding.executePendingBindings()

   

    }


 
    @get: LayoutRes
    abstract val layoutid: Int

    abstract fun getViewModel(): ViewModel

    abstract fun getBindingVariable(): Int

  
    private fun getViewModelClass(): Class<ViewModel> {
        val type =
            (javaClass.genericSuperclass as ParameterizedType).actualTypeArguments[0]          
        return type as Class<ViewModel>
    }


}

Now I am using this BaseActivity in my SplashActivity:-

class SplashScreen : BaseActivity<SplashScreenViewModel, ActivitySplashBinding>() {
    private lateinit var viewModel: SplashScreenViewModel


    


    override fun onFailure(message: String) {
    }

    override fun onStarted() {
    }

    override fun onSuccess() {
    }

    override fun getViewModel(): SplashScreenViewModel {
        viewModel = ViewModelProvider(this).get(SplashScreenViewModel::class.java)
        return viewModel
    }

    override fun getBindingVariable(): Int {
        return BR.splash_viewmodel
    }

    override val layoutid: Int
        get() = R.layout.activity_splash
    
}

I have used this answer as a reference to implement this BaseActivity.kt : How to have generic ViewModel in BaseActivty class

But I am getting a blank white screen while running the app.

Can you please tell me what is the problem here or how to make this BaseActivity (without using dependency injection)

Answer 1

you have overridden the wrong onCreate

override fun onCreate(savedInstanceState: Bundle?) {

I did play around with something like that few years ago, you can find my approach here