我正试图在Fragment中显示recyclerView，但我遇到了一个错误

Question

class FeedRecyclerAdapter (private val postList : ArrayList<Post>) : RecyclerView.Adapter<FeedRecyclerAdapter.PostHolder>() {
class PostHolder(val binding: FragmentDataBinding) : RecyclerView.ViewHolder(binding.root)
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): PostHolder {
val binding = FragmentDataBinding.inflate(LayoutInflater.from(parent.context),parent,false)
return PostHolder(binding)
}
override fun onBindViewHolder(holder: PostHolder, position: Int) {
holder.binding.verimText.text = postList.get(position).lsi
}
override fun getItemCount(): Int {
return postList.size
}

这是为recyclerView编写的代码。

private lateinit var firestore: FirebaseFirestore
private lateinit var auth: FirebaseAuth
private var _binding: FragmentDataBinding? = null
private val binding get() = _binding!!
private lateinit var postArrayList : ArrayList<Post>
private lateinit var feedAdapter : FeedRecyclerAdapter

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
auth = Firebase.auth
firestore = Firebase.firestore
postArrayList = ArrayList<Post>()
feedAdapter = FeedRecyclerAdapter(postArrayList)
getData()
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentDataBinding.inflate(inflater, container, false)
val view = binding.root

return view
}

private fun getData(){
firestore.collection("Posts").addSnapshotListener { value, error ->
if (error!=null){
Toast.makeText(requireContext(),error.localizedMessage,Toast.LENGTH_SHORT).show()
}else{
if (value !=null){
if (!value.isEmpty){
val documents = value.documents
for (document in documents){
val araziBoyutu = document.get("Arazi Boyutu") as String
val araziEgimi = document.get("Arazi Eğimi") as String
val panelBoyutu = document.get("Panel Boyutu") as String
val panelSayisi = document.get("Panel Sayisi") as String
val sehir = document.get("Şehir") as String

val post = Post(panelSayisi,panelBoyutu,araziEgimi,araziBoyutu,sehir)
postArrayList.add(post)
recyclerView.adapter = FeedRecyclerAdapter(postArrayList)

}
feedAdapter.notifyDataSetChanged()
}
}
}
}
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding.recyclerView.adapter = feedAdapter
recyclerView.layoutManager = LinearLayoutManager(activity)

这里的代码是我定义RecylcerView并保存信息的部分。

我可以提取数据，我可以在firebase上看到它，当我用println打印它时，我可以从控制台中读取它，我可以转到应该写入文本的页面，但我在我试图打印的verimText TextView中看不到这些数据。

Answer 1

添加post后尝试调用notifyDataSetChanged()或notifyItemRangeInserted()。

Answer 2

Recyclerview应在onViewCreated方法中声明

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val recyclerView = view.findViewById(R.id.recyclerView) as RecyclerView
recyclerView.layoutManager = LinearLayoutManager(activity)
recyclerView.adapter = FeedRecyclerAdapter(postArrayList)
}

Answer 3

移动这条线

recyclerView.adapter = FeedRecyclerAdapter(postArrayList)

至

val post = Post(panelSayisi,panelBoyutu,araziEgimi,araziBoyutu,sehir)
postArrayList.add(post)
recyclerView.adapter = FeedRecyclerAdapter(postArrayList)//move to here