从活动返回后，错误 lateinit 属性适配器尚未初始化

Question

我对这段代码有问题。添加 SearchView 的代码后，每次我点击一个元素进入 StoreActivity，当我回来时我收到错误

kotlin.UninitializedPropertyAccessException：lateinit 属性适配器尚未初始化

排上

适配器过滤器过滤器（新文本）

我该如何解决这个错误？我不明白...

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

此错误意味着您在初始化适配器之前正在使用该适配器。这里可能是因为你的商店的回调是异步的。

解决此问题的一种方法是将 a 放入MutableList适配器中并在 onCreate 时使用空列表对其进行初始化：

private lateinit var adapter: MyStoreRecyclerViewAdapter


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

然后当您的 Stores 回调被调用时：

adapter.list = stores

另外，不要忘记在设置列表后调用notifyDataSetChanged()，adapter否则您的更改将不可见