Error lateinit property adapter has not been initialized after come back from activity

Question

I've a problem with this code. After adding the code for the SearchView, every time that I click on one element going to StoreActivity, when I come back I receive the error

kotlin.UninitializedPropertyAccessException: lateinit property adapter has not been initialized

on row

adapter.filter.filter(newText)

How I can resolve this error? I don't understand...

class HomeFragment : BaseFragment() {

    private lateinit var adapter: MyStoreRecyclerViewAdapter
    private var stores: List<StoreRealm> = ArrayList()

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {

        return inflater.inflate(R.layout.fragment_home, container, false)
    }

    override fun onResume() {
        super.onResume()
        setHasOptionsMenu(true)

        if (isAdded) {
            val systemService = this.context.getSystemService(Context.LOCATION_SERVICE) as LocationManager
            BLocationManager(this.context).getLocation {
                loadHome()
                if (!systemService.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
                    showEnableGpsDialog()
                } else {
                    gpsWarning.visibility = View.GONE
                }
            }
        }
    }

    override fun onCreateOptionsMenu(menu: Menu?, inflater: MenuInflater?) {
        inflater?.inflate(R.menu.search_store, menu)
        val search: MenuItem = menu!!.findItem(R.id.searchStore)
        val searchView: SearchView = search.actionView as SearchView
        search(searchView)
        searchView.maxWidth = Int.MAX_VALUE

        super.onCreateOptionsMenu(menu, inflater)
    }

    private fun loadHome() {
        loading_spinner?.visibility = View.VISIBLE
        StoreService.getStores(
            AuthManager.getMe()?.id!!, 0, BLocationManager.lat, BLocationManager.lon
        ) { response ->
            loading_spinner?.visibility = View.GONE
            if (response.getResult() != null && response.getResult()?.isNotEmpty()!!) {
                no_data_view?.visibility = View.GONE
                store_view?.visibility = View.VISIBLE

                stores = response.getResult()!!
                // set up the RecyclerView
                val recyclerView = view.store_recycler
                recyclerView.layoutManager = GridLayoutManager(this.context, 1)
                adapter = MyStoreRecyclerViewAdapter(stores) {
                    val intent = Intent(this.context, StoreActivity::class.java)
                    intent.putExtra("store_id", it.id)
                    startActivity(intent)
                }
                recyclerView.adapter = adapter
            } else {
                no_data_view?.visibility = View.VISIBLE
                store_view?.visibility = View.GONE
            }

            if ((response.getError() as? UnknownHostException) != null) {
                AuthManager.logout(this.activity)
                NavigationManager.goToLogin(this.activity)
            }
        }
    }

    private fun search(searchView: SearchView) {
        searchView.setOnQueryTextListener(object : SearchView.OnQueryTextListener {
            override fun onQueryTextSubmit(query: String?): Boolean {
                return false
            }

            override fun onQueryTextChange(newText: String?): Boolean {
                adapter.filter.filter(newText)

                return true
            }

        })
    }
}

Answer 1

This error means that you're using the adapter before initializing it. Here it's probably because your store's callback is asynchronous.

One way to fix this problem is to put a MutableList in your adapter and initialize it onCreate with an empty list:

private lateinit var adapter: MyStoreRecyclerViewAdapter


override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        adapter = MyStoreRecyclerViewAdapter(mutableListOf())
        recyclerView.adapter = adapter
}

Then when your Stores' callback is called:

adapter.list = stores

Also, don't forget to call notifyDataSetChanged() on the adapter after setting the List otherwise your changes won't be visible