RecyclerView滚动到聊天屏幕中notifyDataSetChanged的顶部 [英] RecyclerView scrolls to top on notifyDataSetChanged in chat screen

问题描述

我正在尝试使用recyclerView创建消息传递类型的屏幕，该屏幕将从底部开始，并在用户到达聊天的顶部时加载更多数据.但是我面临着这个奇怪的问题.

I am trying to create messaging kind of screen using recyclerView which will start from bottom and will loadMore data when user reached top end of chat. But I am facing this weird issue.

我的recyclerView滚动到调用notifyDataSetChanged的顶部.由于这个原因，onLoadMore被多次调用.

My recyclerView scrolls to top on calling notifyDataSetChanged. Due to this onLoadMore gets called multiple times.

这是我的代码:

LinearLayoutManager llm = new LinearLayoutManager(context);
llm.setOrientation(LinearLayoutManager.VERTICAL);
llm.setStackFromEnd(true);
recyclerView.setLayoutManager(llm);

**在适配器中

 @Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    if (messages.size() > 8 && position == 0 && null != mLoadMoreCallbacks) {
        mLoadMoreCallbacks.onLoadMore();
    }

**活动中

@Override
public void onLoadMore() {
    // Get data from database and add into arrayList
      chatMessagesAdapter.notifyDataSetChanged();
}

只是recyclerView滚动到顶部.如果滚动到顶部停止，则将解决此问题.请帮助我找出造成此问题的原因.预先感谢.

It's just that recyclerView scrolls to top. If scrolling to top stops, this issue will be resolved. Please help me to figure out the cause of this issue. Thanks in advance.

推荐答案

我认为您不应该这样使用onBindViewHolder，删除该代码，适配器应该只绑定模型数据，而不监听滚动.

I think you shouldn't use onBindViewHolder that way, remove that code, the adapter should only bind model data, not listen scrolling.

我通常以这种方式执行"onLoadMore":

I usually do the "onLoadMore" this way:

在活动中:

private boolean isLoading, totallyLoaded; //
RecyclerView mMessages;
LinearLayoutManager manager;
ArrayList<Message> messagesArray;
MessagesAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //...
    mMessages.setHasFixedSize(true);
    manager = new LinearLayoutManager(this);
    manager.setStackFromEnd(true);
    mMessages.setLayoutManager(manager);
    mMessages.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);

            if (manager.findFirstVisibleItemPosition() == 0 && !isLoading && !totallyLoaded) {
                onLoadMore();
                isLoading = true;
            }
        }
    });
    messagesArray = new ArrayList<>();
    adapter = new MessagesAdapter(messagesArray, this);
    mMessages.setAdapter(adapter);
}


@Override
public void onLoadMore() {
    //get more messages...
    messagesArray.addAll(0, moreMessagesArray);
    adapter.notifyItemRangeInserted(0, (int) moreMessagesArray.size();
    isLoading = false;
}

这对我来说很正常，如果服务器不返回更多消息，则使用"totallyLoaded"来停止进行服务器调用.希望对您有帮助.

This works perfeclty for me, and the "totallyLoaded" is used if the server doesn't return more messages, to stop making server calls. Hope it helps you.

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