👀 Views: 56 💬 Answers: 1 📅 Created: 2025-09-06

android recyclerview livedata customview kotlin

I'm prototyping a solution and I'm stuck on something that should probably be simple... After trying multiple solutions online, I still can't figure this out... This might be a silly question, but I've searched everywhere and can't find a clear answer. While developing a client application that utilizes a `RecyclerView`, I've encountered a perplexing issue where a custom view within each item does not update when the underlying data changes. I implemented the `ViewHolder` pattern with `LiveData` to observe changes from my `ViewModel`, but the UI doesn't reflect these changes as expected. Here's a snippet of my `Adapter` code: ```kotlin class MyAdapter(private val itemList: List<MyItem>, private val viewModel: MyViewModel) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() { inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) { private val myCustomView: MyCustomView = itemView.findViewById(R.id.my_custom_view) fun bind(item: MyItem) { myCustomView.setData(item) viewModel.getDataForItem(item.id).observe(itemView.context as LifecycleOwner) { updatedData -> myCustomView.updateData(updatedData) } } } override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder { val view = LayoutInflater.from(parent.context).inflate(R.layout.item_layout, parent, false) return MyViewHolder(view) } override fun onBindViewHolder(holder: MyViewHolder, position: Int) { holder.bind(itemList[position]) } override fun getItemCount(): Int = itemList.size } ``` In my `ViewModel`, I use `MutableLiveData` to hold the updated data, and I've confirmed that the data changes correctly when I debug it. The problem lies in the `MyCustomView` not calling `updateData()` when the observable data changes. I've tried forcing a manual `notifyDataSetChanged()` when the data is updated in the `ViewModel`, but that doesn't seem to help due to potential performance issues. Here’s the relevant part from the `ViewModel`: ```kotlin class MyViewModel : ViewModel() { private val _dataMap = MutableLiveData<Map<Int, UpdatedData>>() val dataMap: LiveData<Map<Int, UpdatedData>> get() = _dataMap fun getDataForItem(id: Int): LiveData<UpdatedData> { // Logic to fetch updated data return Transformations.map(dataMap) { it[id] } } } ``` I'm using Android 14, and both my custom view and the RecyclerView are properly set up in the layout. Is there a best practice for ensuring that the custom view updates correctly when the underlying data changes? What am I missing here? This is part of a larger API I'm building. My development environment is Windows. This is part of a larger CLI tool I'm building. Is there a better approach? Thanks, I really appreciate it! The stack includes Kotlin and several other technologies. I appreciate any insights! Thanks for any help you can provide!