Question

我的问题是，RecyclerView会在我关闭屏幕并重新打开之前什么都不会显示。

我的应用程序包括使用Volley库从GitHub存储库中获取5个文件，然后使用Glide将文本绑定到某些TextViews并将图像绑定到ImageView。但是有时我的RecyclerView中的数据没有显示。

代码如下：

MainActivity.kt

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

    recyclerView.layoutManager = LinearLayoutManager(this)

    val queue = Volley.newRequestQueue(this)
    val baseurl = "https://raw.githubusercontent.com/nubicoud/Dealist/master/"

    val appNames:ArrayList<String> = ArrayList()
    val appDesc:ArrayList<String> = ArrayList()
    val appPrice:ArrayList<String> = ArrayList()
    val appImage:ArrayList<String> = ArrayList()
    val appDownload:ArrayList<String> = ArrayList()

    var url = "${baseurl}name?"
    val appNamesReq = StringRequest(Request.Method.GET, url,
            Response.Listener<String> { response ->
                val appNamesResponse = response.toString()
                for (i in 1..appNamesResponse.lines()[0].toInt()){
                    appNames.add(appNamesResponse.lines()[i])
                }
            },
            Response.ErrorListener {
                errorRequest()
            })
    queue.add(appNamesReq)

    url = "${baseurl}desc?"
    val appDescReq = StringRequest(Request.Method.GET, url,
            Response.Listener<String> { response ->
                val appDescResponse = response.toString()
                for (i in 1..appDescResponse.lines()[0].toInt()){
                    appDesc.add(appDescResponse.lines()[i])
                }
            },
            Response.ErrorListener {
                errorRequest()
            })
    queue.add(appDescReq)

    url = "${baseurl}price?"
    val appPriceReq = StringRequest(Request.Method.GET, url,
            Response.Listener<String> { response ->
                val appPriceResponse = response.toString()
                for (i in 1..appPriceResponse.lines()[0].toInt()){
                    appPrice.add(appPriceResponse.lines()[i])
                }
            },
            Response.ErrorListener {
                errorRequest()
            })
    queue.add(appPriceReq)

    url = "${baseurl}image?"
    val appImageReq = StringRequest(Request.Method.GET, url,
            Response.Listener<String> { response ->
                val appImageResponse = response.toString()
                for (i in 1..appImageResponse.lines()[0].toInt()){
                    appImage.add(appImageResponse.lines()[i])
                }
            },
            Response.ErrorListener {
                errorRequest()
            })
    queue.add(appImageReq)
    recyclerView.adapter = AppsAdapter(appNames, appDesc, appPrice, appImage, appDownload)

AppsAdapter.kt

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): AppsAdapter.ViewHolder {
    val view: View = LayoutInflater.from(parent.context).inflate(R.layout.apps_row, parent, false)
    return ViewHolder(view)
}

override fun onBindViewHolder(holder: AppsAdapter.ViewHolder, position: Int) {
    val Context = holder.itemView.context
    holder.name.text = appNames[position]
    holder.description.text = appDesc[position]
    holder.price.text = appPrice[position]
    holder.download.setOnClickListener {
        Context.startActivity(Intent(Intent.ACTION_VIEW, Uri.parse(appDownload[position])))
    }
    Glide.with(Context).load(appImage[position]).into(holder.image)
}

override fun getItemCount() = appNames.size

class ViewHolder(itemView : View) : RecyclerView.ViewHolder(itemView) {
    val image = itemView.findViewById<ImageView>(R.id.image)!!
    val name = itemView.findViewById<TextView>(R.id.name)!!
    val description = itemView.findViewById<TextView>(R.id.description)!!
    val price = itemView.findViewById<TextView>(R.id.price)
    val download = itemView.findViewById<Button>(R.id.download)
}

activity_main.xml

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF"
tools:context=".MainActivity">

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerView"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:background="#FFFFFF"
    app:layout_constraintBottom_toTopOf="@+id/bottomNavigationMenu"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent">

</androidx.recyclerview.widget.RecyclerView>

<com.google.android.material.bottomnavigation.BottomNavigationView
    android:id="@+id/bottomNavigationMenu"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/colorPrimary"
    app:itemIconTint="@color/bottomnavbarTextColor"
    app:itemTextColor="@color/bottomnavbarTextColor"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:menu="@menu/nav_menu" />

</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

通过在其他所有操作之前更改下载行为来解决该问题。

首先下载数据，然后执行setContentView(R.layout.activity_main)和recyclerView.layoutManager = LinearLayoutManager(this) recyclerView.adapter = AppsAdapter(appNames, appDesc, appPrice, appImage, appDownload) recyclerView.setHasFixedSize(true) (recyclerView.adapter as AppsAdapter).notifyDataSetChanged()，然后设置RecyclerView。

{{1}}

RecyclerView仅在打开和关闭屏幕后绑定数据

1 个答案: