Android RecyclerView StaggeredGrid 项目在滚动顶部时更改位置

Question

在我的 2 列交错网格中，我使用无限列表的效果自动加载 10 x 10 的元素，除了向上滚动之外，一切正常。前两个元素改变了它们的位置。就像前两项从一列跳到另一列一样。

正如我所读，适配器必须保存每个元素的状态。但是，我不知道该怎么做。

这是我用来显示 StaggeredGrid 功能的主要代码

public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
    private int space;

    public SpacesItemDecoration(int space) {
        this.space = space;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view,
                               RecyclerView parent, RecyclerView.State state) {
        outRect.left = space;
        outRect.right = space;
        outRect.bottom = space+1;

        // Add top margin only for the first item to avoid double space between items
        if(parent.getChildLayoutPosition(view) == 0)
            outRect.top = space;
    }
}

public class SolventViewHolders extends RecyclerView.ViewHolder implements View.OnClickListener {

    public TextView vh_name;
    public TextView vh_price;
    public ImageView vh_image;

    public SolventViewHolders(View v) {
        super(v);
        v.setOnClickListener(this);

        vh_image=(ImageView)v.findViewById(R.id.thumbnail);
        vh_name= (TextView) v.findViewById(R.id.title);
        vh_price= (TextView) v.findViewById(R.id.subtitle);
    }

    public void sendImage(String url) {
        Picasso.with(ctx)
                .load(url)
                .into(vh_image);
    }
    @Override
    public void onClick(View view) {
        int position = getPosition();

        if (user_id != null) {

            openDetail(MyLogs.get(position).getId_item(), MyLogs.get(position).getItemName(), MyLogs.get(position).getPrice(), MyLogs.get(position).getDescrip(), MyLogs.get(position).getId_store(), MyLogs.get(position).getId_store());
        }
    }
}

public class SolventRecyclerViewAdapter  extends RecyclerView.Adapter<SolventViewHolders> {


    private List<productItem> itemList;
    private Context context;

    public SolventRecyclerViewAdapter(Context context, List<productItem> itemList) {
        this.itemList = itemList;
        this.context = context;
    }
    @Override
    public SolventViewHolders onCreateViewHolder(ViewGroup parent, int viewType) {

        View layoutView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_mosaico_defoult, null);
        SolventViewHolders rcv = new SolventViewHolders(layoutView);

        return rcv;
    }

    @Override
    public void onBindViewHolder(SolventViewHolders holder, int position) {

        holder.vh_name.setText(itemList.get(position).getName());
        holder.vh_price.setText("CLP:"+itemList.get(position).getPrice());

    }

    @Override
    public int getItemCount() {
        return this.itemList.size();
    }
}

#编辑1：

这就是我实例化适配器的方式

 recyclerView = (RecyclerView)view.findViewById(R.id.recycler_view);
    recyclerView.setHasFixedSize(true);

    gaggeredGridLayoutManager = new StaggeredGridLayoutManager(2, 1);
    recyclerView.setLayoutManager(gaggeredGridLayoutManager);
    recyclerView.addItemDecoration(new SpacesItemDecoration(2));

    populateList(currentPage);

    rcAdapter= new SolventRecyclerViewAdapter(ctx, MyLogs);
    recyclerView.setAdapter(rcAdapter);

populate 方法作为 json 格式的异步任务响应发生：

                            ...
            for(int i=0; i < lengthJsonArr; i++)
            {

                JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);

                           ...

                MyLogs.add("name,price,etc");
                rcAdapter.notifyDataSetChanged();

            }

这就是我握住 onScroll 的方式：

 recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {

            visibleItemCount = gaggeredGridLayoutManager.getChildCount();
            totalItemCount = gaggeredGridLayoutManager.getItemCount();
            int[] firstVisibleItems = null;
            firstVisibleItems = gaggeredGridLayoutManager.findFirstVisibleItemPositions(firstVisibleItems);
            if (firstVisibleItems != null && firstVisibleItems.length > 0) {
                pastVisiblesItems = firstVisibleItems[0];
            }

            if (loading) {
                if ((visibleItemCount + pastVisiblesItems) >= totalItemCount) {
                    loading= false;
                    Log.d("tag", "LOAD NEXT ITEM");
                    currentPage = currentPage + 1;
                    populateList(currentPage);
                }
            }
        }
    });

我感谢任何帮助

Answer 1

这是一个功能。重新排序和重新定位视图以实现无缝的项目串。

使用

setGapStrategy(int gapStrategy)

设置 StaggeredGridLayoutManager 的间隙处理策略。如果gapStrategy参数与当前策略不同，调用该方法将触发布局请求。

您可能会想要

GAP_HANDLING_NONE

。

不做任何事情来隐藏差距。

Answer 2

发生这种情况是因为当您上下滚动时，持有者无法识别图像视图的宽度和高度。当您向下滚动时，它会清除上方视图，反之亦然。

像这样使用：

@Override
public void onBindViewHolder(ViewHolder viewHolder, int position) {

MyViewHolder vh = (MyViewHolder) viewHolder;
ImageModel item = imageModels.get(position);
RelativeLayout.LayoutParams rlp = (RelativeLayout.LayoutParams)vh.imageView.getLayoutParams();
float ratio = item.getHeight() / item.getWidth();
rlp.height = (int) (rlp.width * ratio);
vh.imageView.setLayoutParams(rlp);
vh.positionTextView.setText("pos: " + position);
vh.imageView.setRatio(item.getRatio());
Picasso.with(mContext).load(item.getUrl()).
placeholder(PlaceHolderDrawableHelper.getBackgroundDrawable(position)).
into(vh.imageView);
}

为了清楚起见，请参阅此链接：Picasso/Glide-RecyclerView-StaggeredGridLayoutManager

Answer 3

如前所述，您可以设置GapStrategy，以便它可以执行任何操作来隐藏间隙：

StaggeredGridLayoutManager.GAP_HANDLING_NONE

除此之外，如果您遇到滚动在列之间留下空间差异的情况，以下解决方案对我有用：

recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
    super.onScrollStateChanged(recyclerView, newState)
    if (newState == RecyclerView.SCROLL_STATE_IDLE) {
        recyclerView.invalidateItemDecorations()
    }
}})

添加滚动侦听器以在没有滚动时使项目装饰无效，使位置保持应有的状态！