ViewModelProvider in MainActivity

Question

I tried something but ı cant fix this error this is my mainactivitycode

class MainActivity : AppCompatActivity() {
    private lateinit var binding : ActivityMainBinding
    private lateinit var navController: NavController
    lateinit var viewModel : NewsViewModel
    val db : ArticleDatabase? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        val newsRepository =  NewsRepository(ArticleDatabase(this))
        val viewModelProviderFactory = NewsViewModelProviderFactory(newsRepository)
        viewModel = ViewModelProvider(this,viewModelProviderFactory)[NewsViewModel::class.java]
        navController = Navigation.findNavController(this, R.id.newsNavHostFragment)
        setupWithNavController(binding.bottomNavigationView,navController)



    }
}

and this is fragment code

class BrakingNewsFragment : Fragment() {
    lateinit var viewModel : NewsViewModel
    lateinit var newsAdapter : NewsAdapter
    private lateinit var binding : FragmentBrakingNewsBinding

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

    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        binding = FragmentBrakingNewsBinding.inflate(inflater,container,false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewModel = (activity as MainActivity).viewModel
        setUpRecyclerView()

        viewModel.breakingNews.observe(viewLifecycleOwner, Observer { response ->
            when(response){
                is Resource.Succes -> {
                    response.data?.let {
                        newsAdapter.differ.submitList(it.articles)
                    }
                }
                is Resource.Loading -> {
                    println("abcabc")
                }
            }
        })
    }
    private fun setUpRecyclerView(){
        newsAdapter = NewsAdapter()
        binding.breakingNewsRecyclerView.apply {
            adapter = newsAdapter
            layoutManager = LinearLayoutManager(activity)
        }
    }

}

ı used view modelprovider this is code:

class NewsViewModelProviderFactory(private val newsRepository: NewsRepository) : ViewModelProvider.Factory {

    override fun <T : ViewModel> create(modelClass: Class<T>): T {
            return NewsViewModel(newsRepository) as T
    }
}

logcat error is here

Caused by: android.view.InflateException: Binary XML file line #19 in com.example.newsappkotlin:layout/activity_main: Binary XML file line #19 in com.example.newsappkotlin:layout/activity_main: Error inflating class fragment Caused by: android.view.InflateException: Binary XML file line #19 in com.example.newsappkotlin:layout/activity_main: Error inflating class fragment Caused by: kotlin.UninitializedPropertyAccessException: lateinit property viewModel has not been initialized

How can ı fix

Answer 1

You can't instantiate a view model this way:

viewModel = (activity as MainActivity).viewModel

Why not use the

val viewModel : NewsViewModel by viewModels() 

or since this is proabably a sharedViewModel with the activity:

val viewModel: NewsViewModel by activityViewModels()

You will need the kotlin extension dependency for viewModels before you can do this.

dependencies {
    implementation "androidx.fragment:fragment-ktx:1.6.1"
}