Question

毋庸置疑，我遇到了很多针对这一特定问题的解决方案。我删除了scrollListener并在我的片段中实现了它，我使用notifyItemRangeInserted而不是notifyDataSetChanged。问题是，这些解决方案都没有对我有用......我在我的应用程序中显示了一组YouTube视频。我的数据集确实已更新;事情就是当我向下滚动时，滚动位置会移动到顶部，即我的数据集中的第一项。这是我活动的片段：

private void setUpRecyclerView()
{
    mRecyclerView.setHasFixedSize(true);
    linearLayoutManager = new LinearLayoutManager(getActivity());
    linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
    mRecyclerView.setLayoutManager(linearLayoutManager);
    mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);
            totalItemCount = linearLayoutManager.getItemCount();
            lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
            if (!loading && totalItemCount <= (lastVisibleItem + visibleThreshold))
            {
                loadMorePosts();
                loading = true;
            }
        }
    });

    initAdapter();
}

private void initAdapter()
{
    adapter = new MyAdapter(mDataSet, getActivity());
    mRecyclerView.setAdapter(adapter);
    skeletonScreen = Skeleton.bind(mRecyclerView)
            .adapter(adapter)
            .shimmer(true)
            .angle(30)
            .duration(1200)
            .count(10)
            .load(R.layout.youtube_item)
            .show();
}

private void loadVideos(final OnLoadPlayListCallback videosCallback, String pageToken)
{
    Call<FullChannelPlayListData> mcallPlayList = mYouTubeService.getPlayList(
            Tags.VALUE_SNIPPET,
            20,
            mPlayListId,
            getActivity().getResources().getString(R.string.youtube_data_api_key),
            pageToken
            );

    mcallPlayList.enqueue(new Callback<FullChannelPlayListData>() {
        @Override
        public void onResponse(Call<FullChannelPlayListData> call, Response<FullChannelPlayListData> response) {
            if (response.code() == 200)
            {
                Log.d("FullPlayListSuccessful", response.message());
                videosCallback.onSuccessfulRequest(response.body());
            }
            else Log.d("FullPlayListUnsuccess", response.message());

        }

        @Override
        public void onFailure(Call<FullChannelPlayListData> call, Throwable t) {
            videosCallback.onFailureRequest(t);
        }
    });
}

 @Override
public void onSuccessfulRequest(FullChannelPlayListData fullChannelPlayListData)
{
    Log.d(TAG, "onSuccessfulRequest Item size = "+ fullChannelPlayListData.getItems().size());
    if (StringUtils.isNotEmpty(mNextPageToken))
        removeFooter();

    for (FullPlayListItems mItem: fullChannelPlayListData.getItems())
    {
        FullPlayListItems randomItem = getVideoFromDataSet(mItem.getSnippet().getResourceId().getVideoId(), mDataSet);
        if (randomItem == null) {
            mDataSet.add(mItem);
        }
    }

    adapter.notifyItemRangeInserted(adapter.getItemCount(), mDataSet.size());

    mRecyclerView.postDelayed(new Runnable() {
        @Override
        public void run() {
            skeletonScreen.hide();
        }
    }, 2000);


    mNextPageToken = fullChannelPlayListData.getNextPageToken();
    setLoaded();

}

public void setLoaded() {
    loading = false;
}

我真的可以使用一些帮助......

更新 MyAdapter类

 public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>
{

    private List<FullPlayListItems> mDataSet;
    private Context mActivity;
    private static final int YOUTUBE_ITEM_VIEW_TYPE = 0;
    private static final int PROGRESS_BAR_ITEM_VIEW_TYPE = 1;

    public MyAdapter(List<FullPlayListItems> mDataSet, Context mActivity) {
        this.mDataSet = mDataSet;
        this.mActivity = mActivity;
    }


    public class ProgressViewHolder extends RecyclerView.ViewHolder
    {
        @BindView(R.id.pBarLoadMorePosts)
        ProgressBar pBarLoadMore;

        public ProgressViewHolder(View itemView) {
            super(itemView);
            ButterKnife.bind(this, itemView);
        }
    }


    @Override
    public int getItemViewType(int position) {
        return mDataSet.get(position) != null ? YOUTUBE_ITEM_VIEW_TYPE : PROGRESS_BAR_ITEM_VIEW_TYPE;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
    {
        RecyclerView.ViewHolder viewHolder;
        if (viewType == PROGRESS_BAR_ITEM_VIEW_TYPE)
        {
            View pBarLayoutView = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.footer_loader, parent, false);
            viewHolder = new ProgressViewHolder(pBarLayoutView);
        }
        else
        {
            View postItemLayoutView = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.youtube_item, parent, false);
            viewHolder = new YoutubeItemViewHolder(postItemLayoutView);
        }
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position)
    {
        int viewType = getItemViewType(position);
        FullPlayListItems mVideoItem = mDataSet.get(position);

        switch (viewType)
        {
            case PROGRESS_BAR_ITEM_VIEW_TYPE:
                ProgressViewHolder progressViewHolder = (ProgressViewHolder) holder;
                progressViewHolder.pBarLoadMore.getIndeterminateDrawable().setColorFilter(CoreApplication.getRes().getColor(R.color.colorPrimary), PorterDuff.Mode.SRC_IN);
                break;
            case YOUTUBE_ITEM_VIEW_TYPE:
            default:
                YoutubeItemViewHolder youtubeItemViewHolder = (YoutubeItemViewHolder) holder;
                youtubeItemViewHolder.mVideoTitle.setText(mVideoItem.getSnippet().getTitle());
                youtubeItemViewHolder.sdvYoutubeThumbnail.setImageURI(Uri.parse(mVideoItem.getSnippet().getThumbnails().getHigh().getUrl()));

        }
    }


    @Override
    public int getItemCount() {
        return mDataSet != null ? mDataSet.size() : 0;
    }

    public class YoutubeItemViewHolder extends RecyclerView.ViewHolder
    {
        TextView mVideoTitle;
        SimpleDraweeView sdvYoutubeThumbnail;

        public YoutubeItemViewHolder(View itemView)
        {
            super(itemView);
            mVideoTitle = (TextView)itemView.findViewById(R.id.tv_video_title);
            sdvYoutubeThumbnail = (SimpleDraweeView)itemView.findViewById(R.id.sdv_thumbnail);
        }
    }
}

这是我的onViewCreated：

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    mPlayListId = getArguments().getString(Tags.YT_CHANNEL_PLAYLIST_ID);
    setUpRecyclerView();
    // Like I said initially mNextPageToken is empty
    loadVideos(this, mNextPageToken);
}

Answer 1

只需通知onSuccessfulRequest（）方法中的数据更改。

adapter.notifyDataSetChanged();

Answer 2

我不知道这个答案对你有帮助。无论如何，请尝试，

将此方法添加到MyAdapter

public void addItem(VideoSectionsActivity item){
mDataSet.add(item);
notifyItemInserted(mDataSet.size() - 1);
}

并更改您的onSuccessfulRequest()

@Override
public void onSuccessfulRequest(FullChannelPlayListData fullChannelPlayListData)
{
    Log.d(TAG, "onSuccessfulRequest Item size = "+ fullChannelPlayListData.getItems().size());
    if (StringUtils.isNotEmpty(mNextPageToken))
        removeFooter();

    for (FullPlayListItems mItem: fullChannelPlayListData.getItems())
    {
        FullPlayListItems randomItem = getVideoFromDataSet(mItem.getSnippet().getResourceId().getVideoId(), mDataSet);
        if (randomItem == null) {
            adapter.addItem(mItem);
        }
    }



    mRecyclerView.postDelayed(new Runnable() {
        @Override
        public void run() {
            skeletonScreen.hide();
        }
    }, 2000);


    mNextPageToken = fullChannelPlayListData.getNextPageToken();
    setLoaded();

}

<强>更新

并重新安排活动中的代码

    private void setUpRecyclerView()
{
    mRecyclerView.setHasFixedSize(true);
    linearLayoutManager = new LinearLayoutManager(getActivity());
    linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
    mRecyclerView.setLayoutManager(linearLayoutManager);
    initAdapter();
    mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);
            totalItemCount = linearLayoutManager.getItemCount();
            lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
            if (!loading && totalItemCount <= (lastVisibleItem + visibleThreshold))
            {
                loadMorePosts();
                loading = true;
            }
        }
    });

}

滚动时在recyclerview中更新数据集会将滚动条发送到顶部

2 个答案: