Android RecyclerView onBindViewHolder Called Twice（适配器创建时第一次）

Question

我有简单的 RecyclerViewAdapter 类：

class TariffsCardAdapter(context: Context, tariffCardItems: List<ItemsItem?>?) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {

   private var context: Context? = null
   private var tariffCardItems: ArrayList<ItemsItem?>? = null

    init {
      this.context=context
      this.tariffCardItems=tariffCardItems as ArrayList<ItemsItem?>
    }

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

   override fun getItemCount(): Int {
       return tariffCardItems!!.size
   }//getItemCount ends

   override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {

     val viewHolder = holder as TariffsCardAdapterViewHolder
     Log.e("posX","pos:::".plus(position))
   }

   private inner class TariffsCardAdapterViewHolder : RecyclerView.ViewHolder {
      var text: TextView? = null
      constructor(row: View) : super(row) {
         text= row.findViewById(R.id.text) as TextView
      }
   }
}

现在假设我的 tariffCardItems: List 在列表中只有 5 个我想显示的项目！

问题是当适配器第一次被实例化时； onBindViewHolder 方法调用了两次！

以便日志值打印为：

pos:::0

pos:::1

pos:::0

pos:::1

这意味着我的回收站视图位置将是1！ 并且第一个视图将使用 list item at 1 index 创建，这是错误的，应该是 0

简单来说，recycler 视图的第一个子视图是由 1 个位置值创建的，这是错误的

谁能帮我弄清楚我做错了什么

提前致谢和问候

Answer 1

这仅仅是因为您在代码中调用适配器 2，recyclerview 的 bindviewholder 应该用来绑定数据而不是调用 viewholder。

class TariffsCardAdapter(context: Context, tariffCardItems: List<ItemsItem?>?) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {

   private var context: Context? = null
   private var tariffCardItems: ArrayList<ItemsItem?>? = null

    init {
      this.context=context
      this.tariffCardItems=tariffCardItems as ArrayList<ItemsItem?>
    }

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

   override fun getItemCount(): Int {
       return tariffCardItems!!.size
   }//getItemCount ends

   override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {

                //bind data
   }

   private inner class TariffsCardAdapterViewHolder : RecyclerView.ViewHolder {
      var text: TextView? = null
      constructor(row: View) : super(row) {
         text= row.findViewById(R.id.text) as TextView
      }
   }
}

例如你的适配器应该是这样的

class CustomAdapter(val userList: ArrayList<User>) : RecyclerView.Adapter<CustomAdapter.ViewHolder>() {

    //this method is returning the view for each item in the list
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CustomAdapter.ViewHolder {
        val v = LayoutInflater.from(parent.context).inflate(R.layout.list_layout, parent, false)
        return ViewHolder(v)
    }

    //this method is binding the data on the list
    override fun onBindViewHolder(holder: CustomAdapter.ViewHolder, position: Int) {
        holder.bindItems(userList[position])
    }

    //this method is giving the size of the list
    override fun getItemCount(): Int {
        return userList.size
    }

    //the class is hodling the list view
    class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

        fun bindItems(user: User) {
            val textViewName = itemView.findViewById(R.id.textViewUsername) as TextView
            val textViewAddress  = itemView.findViewById(R.id.textViewAddress) as TextView
            textViewName.text = user.name
            textViewAddress.text = user.address
        }
    }
}

您的代码中的这个方法调用了两次

 val viewHolder = holder as TariffsCardAdapterViewHolder
     Log.e("posX","pos:::".plus(position))