我必须做一些像 Instagram 那样的事情。我有一个用于报道的水平 RecyclerView,下面有一个用于提要的垂直 RecyclerView。我想完成相同的滚动行为(故事应该在滚动时与提要一起出现,而不是固定在顶部)。我找到的唯一解决方案是 NestedScrollView,但它对 RecyclerViews 的性能极其糟糕,我的屏幕几乎永远冻结。我尝试了很多在这里找到的技巧,如nestedScrollEnabled、autoLayoutMeasure等,但没有任何效果。谢谢。
抱歉,如果这个解释太抽象。如果您需要我说得更明确,请告诉我。
public class VerticalAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{
private static final int TYPE_HEADER = 0;
private static final int TYPE_POST = 1;
List<Post> posts;
List<FeedItems> feedItems; //this array is going to populate the horizontal recycler view. Notice that is passed it on the adapter constructor
public VerticalAdapter(List<Post> posts,List<FeedItems> feedItems) {
this.posts = posts;
this.feedItems = feedItems;
}
public void notifyFeedChanged(List<FeedItems> newFeedItems){
this.feedItems.clear();
this.feedItems = newFeedItems; //set the new feed items in the array
notifyItemChanged(0); //tell the main recycler view "Hey, update your first position". This will cause the onBindViewHolder to be called again an thus, the new items will be set into the horizontal recycler view
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == TYPE_HEADER)
return new HeaderViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.your_header_layout, false));
else if (viewType == TYPE_POST)
return new PostViewHolder (LayoutInflater.from(parent.getContext()).inflate(R.layout.your_post_layout, false));
throw new RuntimeException("Don't know this type");
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof HeaderViewHolder){
//set adapter for the horizontal recycler view
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(((HeaderViewHolder) holder).recyclerView.getContext(),LinearLayoutManager.HORIZONTAL, false)
((HeaderViewHolder) holder).recyclerView.setLayoutManager(linearLayoutManager);
if (((HeaderViewHolder) holder).recyclerView.getAdapter() == null){ //only create the adapter the first time. the following times update the values
AnotherAdaterYouNeedToCreateForTheHorizontalRecyclerView adapter = new AnotherAdaterYouNeedToCreateForTheHorizontalRecyclerView(feedItems);
((HeaderViewHolder) holder).recyclerView.setAdapter(adapter);
}else {
((HeaderViewHolder) holder).recyclerView.getAdapter().notifyDataSetChanged();
}
}else if (holder instanceof PostViewHolder){
//just do the normal post binding
}
}
@Override
public int getItemCount() {
return posts.size() + 1; // +1 because of the header
}
@Override
public int getItemViewType(int position) {
return position == 0 ? TYPE_HEADER : TYPE_POST;
}
private class HeaderViewHolder extends RecyclerView.ViewHolder{
RecyclerView recyclerView;
public HeaderViewHolder(View itemView) {
super(itemView);
recyclerView = itemView.findViewById(R.id.the_recycler_view_id_on_the_heaedr_layout_file);
}
}
private class PostViewHolder extends RecyclerView.ViewHolder{
ImageView imageView;
public PostViewHolder(View itemView) {
super(itemView);
imageView = itemView.findViewById(R.id.post_image_view_or_whatever);
}
}}
因此,您的垂直回收器视图具有垂直绘制的帖子项目(或您的帖子类别),这是很容易实现的。现在,对于水平视图,您应该实现一个 recyclerview 标头(查看我的适配器示例)。标题布局将有另一个水平回收器视图。
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