Android Firebase chat RecyclerView auto scroll to bottom when new item is added

Question

im developing an android chat using firebase.

i tried to research about this problem but i cant find a good solutions.

hope someone can help me.

my p

Answer 1

Just try below code :

         @Override
            public void onStart() {
                super.onStart();
                mFirebaseAdapter1 = new FirebaseRecyclerAdapter<ChatModel, ChatMessageViewHolder>(ChatModel.class,
                        R.layout.textview,
                        ChatMessageViewHolder.class,
                        ref_chatchildnode1) {
                    @Override
                    protected void populateViewHolder(ChatMessageViewHolder chatMessageViewHolder, ChatModel m, int i) {



                        chatMessageViewHolder.sender.setText(m.getSender());
                        chatMessageViewHolder.msg.setText(m.getMessage());

                    }
                };
                mRecyclerView.setAdapter(mFirebaseAdapter1);

        if (mFirebaseAdapter1 != null) { 
                    mRecyclerView.postDelayed(new Runnable() {
                     @Override
                     public void run() { 
                         mRecyclerView.smoothScrollToPosition(mFirebaseAdapter1.getItemCount() - 1);
                     }
                  }, 5); 
              }
            }

Answer 2

I know it is an old thread, but maybe this will be helpful.

In place where you add new message:

yourRVAdapter.addMessage("New message")
val position = yourRVAdapter.itemCount.minus(1) // itemCount will return the size of RV items 
//Now just call your recyclerView.scrollToPosition(int)
chatRV.scrollToPosition(position)

Answer 3

Have a look at step 6 of the Firebase codelab for Android, which uses an AdapterDataObserver for this:

mFirebaseAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
   @Override
   public void onItemRangeInserted(int positionStart, int itemCount) {
       super.onItemRangeInserted(positionStart, itemCount);
       int friendlyMessageCount = mFirebaseAdapter.getItemCount();
       int lastVisiblePosition =
              mLinearLayoutManager.findLastCompletelyVisibleItemPosition();
       // If the recycler view is initially being loaded or the 
       // user is at the bottom of the list, scroll to the bottom 
       // of the list to show the newly added message.
       if (lastVisiblePosition == -1 ||
               (positionStart >= (friendlyMessageCount - 1) &&
                       lastVisiblePosition == (positionStart - 1))) {
           mMessageRecyclerView.scrollToPosition(positionStart);
       }
   }
});

Answer 4

adapter.registerAdapterDataObserver(object : RecyclerView.AdapterDataObserver() {
        override fun onItemRangeInserted(positionStart: Int, itemCount: Int) {
            
         CommentRv.scrollToPosition(adapter.itemCount.minus(1))
        }
    })