Question

我需要使用recyclerView显示Firebase数据库中的数据。一切正常，我可以看到卡，但卡上没有其他所有数据。

这是我的适配器类：

class MyAdapter(c: Context, t: ArrayList<Thoughts>) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {

var context : Context
    var theThoughts : ArrayList<Thoughts>

    init{
        context = c
        theThoughts = t
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        return MyViewHolder(LayoutInflater.from(context).inflate(R.layout.card_view01, parent, false))
    }//end onCreateViewHolder

    override fun getItemCount(): Int {
        return theThoughts.size
    }//end getItemCount

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        //holder.theTopicAdapter.text[position]
        //holder.theThoughtAdapter.text[position]
        //it works fine withOUT these two lines up
    }//end onBindViewHolder

    class MyViewHolder(itemView:View):RecyclerView.ViewHolder(itemView) {

        var theTopicAdapter: TextView
        var theThoughtAdapter: TextView

        init{
            //super.itemView
            theTopicAdapter = itemView.textViewCard01
            theThoughtAdapter = itemView.textViewCard02
        }

        fun MyViewHolder(itemView: View){
            super.itemView
            theTopicAdapter = itemView.textViewCard01
            theThoughtAdapter = itemView.textViewCard02
        }//end MyViewHolder function
        }//end MyViewHolder class
}//end MyAdapter class

这是我获取数据并显示它的代码：

databaseReference.addValueEventListener(object: ValueEventListener {
            override fun onDataChange(p0: DataSnapshot) {
                if (p0.exists()){
                    for (thought in p0.children){
                        //var theTopicGetter = thought.child("theTopic").value.toString()
                        val t: Thoughts = thought.getValue(Thoughts::class.java)!!
                        list.add(t)
                    }//end for loop
                }//end if
                adapter = MyAdapter(this@SeePreviousThoughts, list)
                recyclerView.adapter = adapter
            }//end onDataChange
            override fun onCancelled(p0: DatabaseError) {
                Toast.makeText(this@SeePreviousThoughts, "error, please try again.", Toast.LENGTH_SHORT).show()
            }
        })//end the listener

这是全班同学：

class Thoughts() {
    lateinit var theID: String
    lateinit var theCode: String
    lateinit var theTopic: String
    lateinit var theThought: String

    constructor(theID: String, theCode: String, theTopic: String, theThought: String) : this() {
            this.theID = theID
            this.theCode = theCode
            this.theTopic = theTopic
            this.theThought = theThought
    }

}

我应该从数据库中获取数据，并且应该将其显示在每张卡上，但是这些卡只是空的。 this is a screenshot of the empty recyclerView xml文件中默认包含主题和思想一词。

我想我的问题是，从未使用过类MyViewHolder中的函数MyViewHolder ... a screenshot of the code that isn't being used

Answer 1

问题出在override fun onBindViewHolder(holder: MyViewHolder, position: Int)方法中。此适配器有效：

class MyAdapter(val context: Context, val  theThoughts: ArrayList<Thoughts>) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        return MyViewHolder(LayoutInflater.from(context).inflate(R.layout.card_view01, parent, false))
    }//end onCreateViewHolder

    override fun getItemCount(): Int {
        return theThoughts.size
    }//end getItemCount

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        holder.theTopicAdapter.text = theThoughts[position].theTopic
        holder.theThoughtAdapter.text = theThoughts[position].theThought
    }//end onBindViewHolder

    class MyViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {

        lateinit var theTopicAdapter: TextView
        lateinit var theThoughtAdapter: TextView

        fun MyViewHolder(itemView: View){
            super.itemView
            theTopicAdapter = itemView.textViewCard01
            theThoughtAdapter = itemView.textViewCard02
        }//end MyViewHolder function
    }//end MyViewHolder class
}//end MyAdapter class

Firebase实时数据不会显示在我的recyclerView上

1 个答案: