Recyclerview没有显示Firebase Kotlin的数据 [英] Recyclerview is not showing data from Firebase Kotlin

问题描述

正如标题所述，自昨天 Kotlin 开始使用.我想用 Firebase 中的数据填充 RecyclerView .

As title says, I'm using since yesterday Kotlin. I want to populate a RecyclerView with data from Firebase.

我尝试了一些事情，我构建了一个适配器，并尝试填充 RecyclerView ，我的数据进入了Firebasebase，但没有显示在 RecyclerView 中，并且没有出现任何错误.

I tried something, I built an Adapter and tried to populate the RecyclerView, my data is going to Firebasebase but not showing in the RecyclerView and I get no errors.

我找不到与科特林语言有关的问题的任何教程

I couldn't find any tutorials for my problem with Kotlin language

这是我的适配器:

class QuestionAdapter(var items : ArrayList<Question>): RecyclerView.Adapter<QuestionAdapter.ViewHolder>() {

override fun getItemCount(): Int {
    return items.size
}

override fun onBindViewHolder(holder: ViewHolder?, position: Int) {
    var userDto = items[position]
    holder?.titleTextView?.text = userDto.titlu
    holder?.msgTextView?.text = userDto.uid
}

override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): ViewHolder {
    val itemView = LayoutInflater.from(parent?.context)
            .inflate(R.layout.conv_layout, parent, false)

    return ViewHolder(itemView)
}

class ViewHolder(row: View) : RecyclerView.ViewHolder(row) {
    var titleTextView: TextView? = null
    var msgTextView: TextView? = null

    init {
        this.titleTextView = row?.findViewById<TextView>(R.id.titleTextView)
        this.msgTextView = row?.findViewById<TextView>(R.id.msgTextView)
    }
}
}

这是我的活动"代码:

 private fun populalteQuestionsList() {
    val mChatDatabaseReference = FirebaseDatabase.getInstance().reference.child(Constants.USERS).child(mUserID).child(Constants.CHAT).child(Constants.QUESTION)
    val query = mChatDatabaseReference.orderByChild("time")
    query.addListenerForSingleValueEvent(object: ValueEventListener {
        override fun onDataChange(dataSnapshot: DataSnapshot?) {
            mRecyclerView.layoutManager = LinearLayoutManager(this@MainActivity)
            mRecyclerView.setHasFixedSize(true)
            val  questions = ArrayList<Question>()
            val adapter = QuestionAdapter(questions)
            mRecyclerView.adapter = adapter
        }
        override fun onCancelled(error: DatabaseError?) {
        }
    })
}

推荐答案

Recyclerview未显示Firebase Kotlin的数据

Recyclerview is not showing data from Firebase Kotlin

因为您没有在 questions ArrayList<Question>()

签入您的代码

尝试一下

override fun onDataChange(dataSnapshot: DataSnapshot?) {
            mRecyclerView.layoutManager = LinearLayoutManager(this@MainActivity)
            mRecyclerView.setHasFixedSize(true)
            val  questions = ArrayList<Question>()
            val adapter = QuestionAdapter(questions)
           // add data here inside your questions ArrayList<Question>()
            mRecyclerView.adapter = adapter
        }

这篇关于Recyclerview没有显示Firebase Kotlin的数据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！