👀 Views: 100 💬 Answers: 1 📅 Created: 2025-06-15

android kotlin recyclerview viewmodel animation

I need help solving I'm encountering an issue where RecyclerView item animations are behaving unexpectedly after updating the data from a ViewModel. Specifically, when I change the list in my ViewModel and the RecyclerView is notified to update, the animations aren't triggered as expected. Instead, I see a sudden jump in the UI without any smooth transition. Here is the code snippet for my RecyclerView adapter: ```kotlin class MyAdapter(private var items: List<MyItem>) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() { 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(items[position]) } override fun getItemCount(): Int = items.size fun updateItems(newItems: List<MyItem>) { val diffResult = DiffUtil.calculateDiff(MyDiffCallback(items, newItems)) items = newItems diffResult.dispatchUpdatesTo(this) } inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) { fun bind(item: MyItem) { // Binding logic here } } } ``` In my ViewModel, I have a LiveData that gets updated like this: ```kotlin class MyViewModel : ViewModel() { private val _items = MutableLiveData<List<MyItem>>() val items: LiveData<List<MyItem>> get() = _items fun fetchItems() { // Simulating a network call or database fetch _items.value = listOf(MyItem(...), MyItem(...)) // New list } } ``` I'm observing the LiveData in my Fragment like this: ```kotlin viewModel.items.observe(viewLifecycleOwner) { newItems -> adapter.updateItems(newItems) } ``` The issue arises after I call `fetchItems()` to update the data. The `DiffUtil` seems to calculate the differences correctly, but I don’t see the animations. Upon inspecting the logs, I noticed that `dispatchUpdatesTo(this)` is called, but the RecyclerView just jumps to the new state immediately. I have tried the following: - Ensured I’m using `DiffUtil` correctly, with accurate `areItemsTheSame` and `areContentsTheSame` methods in my `MyDiffCallback`. - Verified that the RecyclerView is not in a layout transition state during the updates. - Experimented with different RecyclerView animations, but nothing seems to take effect. Any suggestions on what I might be missing or how to ensure that smooth animations occur when updating the RecyclerView in this manner? I am using Android 14 with Kotlin 1.8. For context: I'm using Kotlin on Ubuntu 22.04. What would be the recommended way to handle this?