在recyclerview kotlin中插入Firebase快照 [英] inserting firebase snapshot in recyclerview kotlin

问题描述

我有一个简单的回收器视图，该视图从数据库中读取一个列表，将数据记录到控制台时可以看到数据，但它没有显示在回收器视图中

I have a simple recycler view that reads a list from the database, I can see data when I log them to the console, but it doesn't show in the recycler view

下面的功能在包含回收者视图的xml布局的kotlin片段类中

 override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?,
    ): View? {
        // Inflate the layout for this fragment
        val view: View = inflater.inflate(R.layout.fragment_chat_list, container, false)


        view.recyclerView?.setHasFixedSize(true)
        view.recyclerView?.layoutManager = LinearLayoutManager(context)




        ref?.addChildEventListener(object : ChildEventListener {
            override fun onChildAdded(snapshot: DataSnapshot, previousChildName: String?) {
                val bal = snapshot.getValue<UserInfo.Uids>()

                if (bal != null) {
                 UserInfo.Uids(bal.email,bal.uid,bal.displayName)         
               }
                Log.d("RecyclerView",  UserInfo.Uids().toString())
                Log.d("RecyclerView", bal.toString())
                adapter = BalAdapter(requireContext(),  ArrayList<UserInfo.Uids>(),  R.layout.users)
                adapter!!.notifyDataSetChanged()
            }

            override fun onChildChanged(snapshot: DataSnapshot, previousChildName: String?) {
                TODO("Not yet implemented")
            }

                override fun onChildRemoved(snapshot: DataSnapshot) {
                TODO("Not yet implemented")
            }

            override fun onChildMoved(snapshot: DataSnapshot, previousChildName: String?) {
                TODO("Not yet implemented")
            }

            override fun onCancelled(p0: DatabaseError) {
                TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
            }




        })
      
        return  view

    }

• R.layout.fragment_chat_list 是包含回收者视图标记的xml

  • R.layout.fragment_chat_list is the xml containing the recycler view tag

    R.layout.users 是数据xml

    view.recyclerView 是回收站视图标签

    BalAdapter 是适配器类，可以应要求提供，但是我觉得那里的代码是正确的

    BalAdapter is the adapter class, can be provided on request, but I feel the code there is correct

    UserInfo.Uids 是数据类，包含 name 和 email

    adapter 变量在覆盖onCreateView

    推荐答案

    看起来好像您没有在recyclerview中填充任何数据.适配器始终使用空的 ArrayList :

    Doesn't look like you're filling the recyclerview up with any data. The adapter is always initialized with an empty ArrayList:

                                        /* This is an empty ArrayList */
    adapter = BalAdapter(requireContext(),  ArrayList<UserInfo.Uids>(),  R.layout.users)
    

    您需要将您从firebase读取的值添加到arraylist中，然后将该arraylist传递到适配器中

    You'll need to add the values you read from firebase into an arraylist, then pass that arraylist into the adapter

    例如:

    //Before any firebase requests:
    val balList = ArrayList<UserInfo.Uids>()
    adapter = BalAdapter(requireContext(), balList,  R.layout.users)
    
    ...
    
    //After you get data from firebase
    val bal = snapshot.getValue<UserInfo.Uids>()
    balList.add(bal)
    adapter.notifyDataSetChanged()
    
    

    这篇关于在recyclerview kotlin中插入Firebase快照的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！