具有GridLayoutManager的RecyclerView和具有不同viewHolder的第一个元素

Question

我成功地做到了这一点，但是以一种非常规的方式。在我的recyclerView适配器中，我对第一个元素使用了一个不同的viewHolder，一个更大的元素。这将是一个很好的解决方案，但第二个元素将低于第一个元素。所以我做了一个技巧，给recyclerView一个与第一个元素相同的固定高度，这样第一个元素和第二个元素就会重叠，我只需要让第二个元素的可见性消失。

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    switch (viewType) {
        case 0:
            final View view = inflater.inflate(R.layout.big_item, parent, false);
            return new BigViewHolder(view);
        case 2:
            final View view2 = inflater.inflate(R.layout.normal_item, parent, false);
            return new NormalViewHolder(view2);
        default:
            return null;
    }
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    if (position == 1) {
        holder.itemView.setVisibility(View.GONE);
    }}

@Override
public int getItemViewType(int position) {
    if (position == 0) {
        return 0;
    } else return 2;
}

但我并不特别喜欢这种方法。有人有更好的主意吗？

Answer 1

经过一些挖掘和咨询，我得到了一个非常好的结果。我会把它贴在下面：

首先，适配器应该像我在问题中提到的那样，没有隐藏第二个元素：

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

    public static final int TYPE_FIRST_ITEM = 0;
    public static final int TYPE_ITEM = 1;

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        switch (viewType) {
            case TYPE_FIRST_ITEM:
                final View view = inflater.inflate(R.layout.big_item, parent, false);
                return new BigViewHolder(view);
            case TYPE_ITEM:
                final View view2 = inflater.inflate(R.layout.normal_item, parent, false);
                return new NormalViewHolder(view2);
            default:
                return null;
        }
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        switch (holder.getItemViewType()) {
            case TYPE_FIRST_ITEM:
                BigViewHolder bigViewHolder = (BigViewHolder) holder;
                // Do what you need for the first item
                break;
            case TYPE_ITEM:
                NormalViewHolder normalViewHolder = (NormalViewHolder) holder;
                // Do what you for the other items
                break;
        }
    }

    @Override
    public int getItemViewType(int position) {
        if (position == 0) {
            return TYPE_FIRST_ITEM;
        } else return TYPE_ITEM;
    }

    final class NormalViewHolder extends RecyclerView.ViewHolder {
        public NormalViewHolder(View itemView) {
            super(itemView);
        }
        // find your views here
    }

    final class BigViewHolder extends RecyclerView.ViewHolder {
        public BigViewHolder(View itemView) {
            super(itemView);
        }
        // find your views here
    }
}

其次，布局管理器应该实现一个侦听器来指定在特定位置应该有多少个跨度（行）：

RecyclerView mRecyclerView = view.findViewById(R.id.my_recycler_view);
        MyAdapter mAdapter = new MyAdapter();
        GridLayoutManager mLayoutManager = new GridLayoutManager(getActivity(), 2, LinearLayoutManager.HORIZONTAL, false);
        mLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                switch(mAdapter.getItemViewType(position)){
                    case MyAdapter.TYPE_FIRST_ITEM:
                        return 2;
                    case MyAdapter.TYPE_ITEM:
                        return 1;
                    default:
                        return -1;
                }
            }
        });
        mRecyclerView.setAdapter(mAdapter);
        mRecyclerView.setLayoutManager(mLayoutManager);

希望它也能帮助其他人。谢谢迈克·M.的支持。