如何使用RecyclerView适配器在Firebase数据库中检索数据

如何解决如何使用RecyclerView适配器在Firebase数据库中检索数据

我正在制作一个样机应用程序，以使用RecyclerView测试Firebase实时数据库。

您能告诉我为什么以及如何检索数据库大小吗？而不是孩子的name的大小？

当前大小为23，但我不知道如何获取该数据。

主要活动

class MainActivity : AppCompatActivity() {

    var childrenCount: Long = 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        button_storeMovie_main.setOnClickListener {
            Log.d("MainActivity","Storing data in FirebaseDatabase")
            Toast.makeText(this,"Storing data...",Toast.LENGTH_SHORT).show()
            storeMovieInFirebaseDatabase()
        }

        button_debug_main.setOnClickListener {
            val database = FirebaseDatabase.getInstance().getReference("/movies/")
            database.addValueEventListener(object : ValueEventListener {
                override fun onDataChange(snapshot: DataSnapshot) {
                    snapshot.children.forEach {
                        Log.d("MainActivity","$it")
                        val dataValue = it.getValue(Movie::class.java)
                        if (dataValue != null) recyclerView_main.adapter = MainAdapter(dataValue)
                    }
                    childrenCount = snapshot.childrenCount
                    Log.d("MainActivity","Number of children = $childrenCount")
                }
                override fun onCancelled(error: DatabaseError) {
                }

            })
        }

    }

    private fun storeMovieInFirebaseDatabase() {
        val uid = UUID.randomUUID().toString()
        val title = editText_inputTitle_main.text.toString()
        val price = editText_inputPrice_main.text.toString()
        val movieData = Movie(title,price)
        FirebaseDatabase.getInstance().getReference("/movies/$uid").setValue(movieData)
            .addOnSuccessListener {
                Log.d("MainActivity","Data stored successfully | UID = $uid")
                Toast.makeText(this,"Data stored successfully",Toast.LENGTH_SHORT).show()
                return@addOnSuccessListener
            }
            .addOnFailureListener{
                Log.d("MainActivity","Data failed to store")
                Toast.makeText(this,"Data failed to store",Toast.LENGTH_SHORT).show()
                return@addOnFailureListener
            }

    }
}

class Movie(val name: String,val price: String) {
    constructor(): this("","")
}

RecyclerView适配器

package dcbrh.ph.recyclerviewfirebasedatabase

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.card_view_layout.view.*
import java.util.*

class MainAdapter(val movie: Movie): RecyclerView.Adapter<CustomViewHolder>() {

    val productTitles = listOf("The Bird Box","Extraction","Bad Boys","300 Spartans","Project X")
    override fun getItemCount(): Int {
        return movie.name.count()

    }

    override fun onCreateViewHolder(parent: ViewGroup,viewType: Int): CustomViewHolder {
        val layoutInflater = LayoutInflater.from(parent.context)
        val cellGrid = layoutInflater.inflate(R.layout.card_view_layout,parent,false)
        return CustomViewHolder(cellGrid)
    }

    override fun onBindViewHolder(holder: CustomViewHolder,position: Int) {
//        val productTitles = productTitles.get(position)

        holder.sight.apply {
            cardView_textView_title.text = movie.name
            cardView_textView_price.text = movie.price
        }

    }
}

class CustomViewHolder(val sight: View): RecyclerView.ViewHolder(sight) {}

我的代码仅检索此孩子的name及其大小 Child picture

看看这个应用程序，以了解我说代码检索名称size的意思。 App picture

P.S。我知道它来自我的getItemCount代码。我只是不知道如何解决我当前的问题，即获取数据库大小。