public class LuckyCodeAdapter extends RecyclerView.Adapter<LuckyCodeAdapter.LuckyCodeViewHolder> {
 private Context context;
 private List<String> list;
 private boolean isHide;//隱藏
 private boolean isOpen;//展開

 public LuckyCodeAdapter(Context context) {
  this.context = context;
 }

 @Override
 public LuckyCodeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
  View v = LayoutInflater.from(context).inflate(R.layout.item_tosanpup_lucky_code, parent, false);
  return new LuckyCodeViewHolder(v);
 }

 @Override
 public void onBindViewHolder(LuckyCodeViewHolder holder, final int position) {
  holder.txtLuckyCode.setText(list.get(position));
  if (hideOrShowCallBack != null) {
   holder.txtLuckyCode.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
     if (position == list.size() - 1) {
      if (isOpen) {
       hideOrShowCallBack.hide();
       return;
      }
      if (isHide) {
       hideOrShowCallBack.open();
       return;
      }
     }
    }
   });

  }
 }

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

 //隱藏
 public void setHideList(List<String> newList) {
  this.list = newList;
  notifyDataSetChanged();
  this.isHide = true;
  this.isOpen = false;
 }

 //展開
 public void setOpenList(List<String> openList) {
  this.list = openList;
  this.isOpen = true;
  this.isHide = false;
  notifyDataSetChanged();
 }

 //不需要隱藏/展開
 public void setRealList(List<String> realList) {
  this.list = realList;
  notifyDataSetChanged();
  this.isHide = false;
  this.isOpen = false;
 }

 //清除數據
 public void clearData() {
  if (list != null) {
   this.list.clear();
   notifyDataSetChanged();
  }
 }

 class LuckyCodeViewHolder extends RecyclerView.ViewHolder {
  TextView txtLuckyCode;//幸運號碼

  public LuckyCodeViewHolder(View itemView) {
   super(itemView);
   txtLuckyCode = (TextView) itemView;
  }
 }

 private HideOrShowCallBack hideOrShowCallBack;

 public void setHideOrShowCallBack(HideOrShowCallBack hideOrShowCallBack) {
  this.hideOrShowCallBack = hideOrShowCallBack;
 }

 public interface HideOrShowCallBack {
  void hide();

  void open();
 }
}

//luckyList為真實list，判斷是否需要隱藏
 if (luckyList.size() > 4) {
   luckyCodeHideList = new ArrayList<>();
   luckyCodeOpenList = new ArrayList<>();
   for (int i = 0; i < luckyList.size(); i++) {
    luckyCodeOpenList.add(luckyList.get(i));
   }
   luckyCodeOpenList.add("收起");

   for (int i = 0; i < 3; i++) {
    luckyCodeHideList.add(luckyList.get(i));
   }
   luckyCodeHideList.add("查看更多");
   luckyCodeAdapter.setHideList(luckyCodeHideList);
  } else {
   luckyCodeAdapter.setRealList(luckyList);
  }

luckyCodeAdapter.setHideOrShowCallBack(new LuckyCodeAdapter.HideOrShowCallBack() {
   @Override
   public void hide() {
    luckyCodeAdapter.setHideList(luckyCodeHideList);
   }

   @Override
   public void open() {
    luckyCodeAdapter.setOpenList(luckyCodeOpenList);
   }
  });