How to stay at bottom of List?

Hi I want to use this as a Whatsapp Like Message List. How can I get the list to stay at the bottom if the user is at the bottom when doing submitList on a PagedListEpoxyController?

Means I have 3 states:

1. Init (first time loading the data) -> I want to scroll to the bottom
2. User is already at the bottom after 1 finished and I get new data -> I want to scroll to the bottom
3. User is somewhere in the list aka not bottom after 1 finished and I get new data -> I dont want to scroll to the bottom

How can I archive that? I currently try to do it via the following code but is there a better way of doing it?

val recyclerLayoutManager: LinearLayoutManager = recyclerView.layoutManager as LinearLayoutManager
viewModel.messageList(intent.getStringExtra("roomID")).observe(this@ChatRoom, Observer {
    // Submit Data
    pagingController.submitList(it)

    // Check if we are at the bottom and scroll
    if (recyclerLayoutManager.findLastCompletelyVisibleItemPosition() == recyclerView.childCount) {
        recyclerView.smoothScrollToPosition(recyclerView.childCount)
    }
})

[MTRNord]

I got it. This awnser on stackoverflow gave me the last needed hint: https://stackoverflow.com/a/53316955/4929236

Basicly set the LLM to reverselayout and setStackFromEnd to false. And order the db query in DESC mode

[ghost]

You shouldn’t be scrolling to the bottom of the list - instead there is a great property on LinearLayoutManager to reverse the layout to be bottom to top. That should solve issues #1 and #3. See: https://developer.android.com/reference/android/support/v7/widget/LinearLayoutManager#setreverselayout

As for not scrolling if the user is at a certain position when data is added, you can use the solution explained at https://github.com/airbnb/epoxy/issues/224 and add an adapter data observer. You may actually not need this if you’ve done the above with reverse layout on LLM, but if that doesn’t do the trick, try the below.

controller.getAdapter().registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
    @Override
    public void onItemRangeInserted(int positionStart, int itemCount) {
        if(positionStart == 0) {
            layoutManager.scrollToPosition(0);
       }
    }
});