如何让RecyclerView仅显示2个可滚动的列表项？

我通过ListAdapter在RecyclerView中展示一组操作列表，希望RecyclerView仅显示2个元素且支持滚动，但目前无法实现该效果。相关代码如下：

ListAdapter代码 #

class OperationAdapter(private val onItemClicked: (Operation) -> Unit) :
ListAdapter<Operation, OperationAdapter.OperationViewHolder>(DiffCallback) {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): OperationViewHolder {
        val viewHolder = OperationViewHolder(
            OperationItemBinding.inflate(
                LayoutInflater.from(parent.context),
                parent,
                false
            )
        )
        return viewHolder
    }

    @SuppressLint("ResourceAsColor", "SetTextI18n")
    override fun onBindViewHolder(holder: OperationViewHolder, position: Int) {
        holder.bind(getItem(position))
    }

    class OperationViewHolder(private var binding: OperationItemBinding): RecyclerView.ViewHolder(binding.root) {
        fun bind(operation: Operation){
            if(operation.receive == ACCOUNT.number){
                binding.imageViewItem.setImageResource(R.drawable.ic_type_recieve)
                binding.nameOperation.text = operation.send
                binding.nameOperation.setTextColor(Color.rgb(35, 135, 0))
                val sum = NumberFormat.getCurrencyInstance(Locale("en", "US")).format(operation.sum)
                binding.textSum.text = sum
                binding.textSum.setTextColor(Color.rgb(35, 135, 0))
            }else{
                binding.imageViewItem.setImageResource(R.drawable.ic_type_sent)
                binding.nameOperation.text = operation.receive
                binding.nameOperation.setTextColor(Color.rgb(231, 223,255))
                val sum = NumberFormat.getCurrencyInstance(Locale("en", "US")).format(operation.sum)
                binding.textSum.text = "-$sum"
                binding.textSum.setTextColor(Color.rgb(231, 223,255))
            }
        }
    }

    companion object{
        private val DiffCallback = object: DiffUtil.ItemCallback<Operation>(){
            override fun areItemsTheSame(oldItem: Operation, newItem: Operation): Boolean {
                return oldItem.id == newItem.id
            }

            override fun areContentsTheSame(oldItem: Operation, newItem: Operation): Boolean {
                return oldItem == newItem
            }
        }
    }
}

协程获取Room数据代码 #

GlobalScope.launch(Dispatchers.IO){
    sharedViewModel.getOperationsAll(ACCOUNT.number).collect(){ it ->
        operationAdapter.submitList(it.sortedByDescending { it.time })
    }
}

• 给RecyclerView设置固定高度：如果RecyclerView的高度是wrap_content，它会自动适配所有列表项的高度，导致显示全部元素。可以设置一个刚好能容纳2个列表项的固定高度，比如：

  <androidx.recyclerview.widget.RecyclerView
      android:id="@+id/operationRecyclerView"
      android:layout_width="match_parent"
      android:layout_height="120dp" <!-- 根据你的列表项高度调整此值 -->
      android:scrollbars="vertical" />
  

• 确认布局管理器配置：确保RecyclerView使用的是垂直方向的LinearLayoutManager，默认配置即可，不需要额外限制数量，只要RecyclerView高度足够小，就会自动支持滚动：

  val layoutManager = LinearLayoutManager(context, LinearLayoutManager.VERTICAL, false)
  operationRecyclerView.layoutManager = layoutManager
  

• 检查列表项布局高度：如果列表项的布局高度设置不合理（比如过高），会导致RecyclerView无法显示2个完整项。确保列表项高度是固定值或合适的wrap_content，保证2个项能在设置的RecyclerView高度内完整显示。
• 限制RecyclerView父布局高度：如果RecyclerView的父布局是match_parent且没有高度限制，RecyclerView会占满父布局空间，显示更多元素。要确保父布局的高度约束能让RecyclerView只显示2个项。

内容的提问来源于stack exchange，提问作者Artem Barabash