Question

为什么我出现此错误？

 java.lang.ClassCastException: com.example.pc.mytest.MainItemsRCVAdapter$ViewHolderHeader cannot be cast to com.example.pc.mytest.MainItemsRCVAdapter$ViewHolder

我正在尝试使用Recycler一个标题和一个水平标题。

这是班级：

public class MainItemsRCVAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    private ArrayList<ListMainItem> mainItems;
    private Context mContext;
    private static final int TYPE_HEADER = 0;
    private static final int TYPE_ITEM = 1;


    public MainItemsRCVAdapter(Context context,ArrayList<ListMainItem> maindata) {
        setMaindata(maindata);
        this.mainItems = maindata;
        this.mContext = context;
    }

    public void setMaindata(ArrayList<ListMainItem> maindatahorizon) {
        this.mainItems = maindatahorizon;
    }

    public ArrayList<ListMainItem> getMaindata() {
        return mainItems;
    }
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        if (viewType == TYPE_ITEM) {
            //inflate your layout and pass it to view holder
            View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.main_adapter_horizontal, viewGroup, false);
            return new ViewHolder(v);
        } else if (viewType == TYPE_HEADER) {
            //inflate your layout and pass it to view holder
            View v =  LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.main_item_adapter, viewGroup, false);
            return new ViewHolderHeader(v);
        }
        throw new RuntimeException("there is no type that matches the type " + viewType + " + make sure your using types correctly");

    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int i) {

        if (holder instanceof ViewHolder) {
//            String name = getDataVertical().get(position-1).getImages();
            String name =mainItems.get(i).geImgName();
            String urlimage =mainItems.get(i).getImgUrl();

            ((ViewHolder) holder).tv_items.setText(mainItems.get(i).geImgName());
           // holder.tv_items.setText(mainItems.get(i).geImgName());

            Log.d("###", "Setting name: " + name);

            Picasso.with(mContext)
                    .load(R.drawable.upload).resize(240, 120)
                    .into(((ViewHolder) holder).img_items);
            Log.d("###", "Setting url: " + urlimage);

        } else if (holder instanceof ViewHolderHeader) {
            //cast holder to VHHeader and set data for header.

            ((ViewHolder) holder).tv_items.setText(mainItems.get(i).geImgName());
            Log.d("####", "HEADER");
        }


//
//        viewHolder.tv_items.setText(mainItems.get(i).geImgName());
//        Picasso.with(mContext)
//                .load(mainItems.get(i)
//                        .getImgUrl()).resize(240, 120)
//                .into(viewHolder.img_items);

    }

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

    @Override
    public int getItemViewType(int position) {
        if (isPositionHeader(position)) {
            return TYPE_HEADER;
        }

        return TYPE_ITEM;
    }

    private boolean isPositionHeader(int position) {
        return position == 0;
    }


    public class ViewHolder extends RecyclerView.ViewHolder{
        private TextView tv_items;
        private ImageView img_items;
        private ImageView mDataImgView;

        public ViewHolder(View view) {
            super(view);

            tv_items = (TextView)view.findViewById(R.id.tv_items_horz);
            img_items = (ImageView) view.findViewById(R.id.img_items_horz);
        }
        public ImageView getmDataImgView()
        {
            return mDataImgView;
        }
    }

    public class ViewHolderHeader extends RecyclerView.ViewHolder{
        private final RecyclerView mHorizontalRecyclerView;

        public ViewHolderHeader(View v) {
            super(v);
            mHorizontalRecyclerView = (RecyclerView) v.findViewById(R.id.recycler_view_horizontal);
            MainItemsRCVAdapterHorizontal mAdapter = new MainItemsRCVAdapterHorizontal(getMaindata(), mContext);
            LinearLayoutManager layoutManager
                    = new LinearLayoutManager(mContext, LinearLayoutManager.HORIZONTAL, false);

            mHorizontalRecyclerView.setLayoutManager(layoutManager);
            mHorizontalRecyclerView.setAdapter(mAdapter);
        }
    }
    }

这是横向

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


        private final ArrayList<ListMainItem> mData;
        private final Context mContext;

        public MainItemsRCVAdapterHorizontal(ArrayList<ListMainItem> dataHorizontal,Context context) {
            mData = dataHorizontal;
            mContext=context;
        }

        @Override
        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.main_adapter_horizontal, parent, false);
            return new MainItemsRCVAdapterHorizontal.MyViewHolderHeader(v);
        }

        @Override
        public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
            String name = mData.get(position).geImgName();
            Log.d("###", "Setting name: " + name);
            //   ((RecyclerViewAdapterHorizontal.MyViewHolderHeader) holder).getmDataTextView().setText(name);
            ((MainItemsRCVAdapterHorizontal.MyViewHolderHeader) holder).getmDataImgView().setImageResource(mContext.getResources().getIdentifier(name, "drawable", "com.example.mohamadmouazen.lebgame.Adapters"));

        }

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

        private class MyViewHolderHeader extends RecyclerView.ViewHolder {
            // private final TextView mDataTextView;
            private final ImageView mDataImgView;

            public MyViewHolderHeader(View v) {
                super(v);
                //    mDataTextView = (TextView) v.findViewById(R.id.data_vertical);
                mDataImgView = (ImageView) v.findViewById(R.id.img_items_horz);
            }

            public ImageView getmDataImgView() {
                return mDataImgView;
            }
/*        public TextView getmDataTextView() {
            return mDataTextView;
        }*/
        }
    }

Answer 1

因为您正在进行无效投射。

检查代码：

        } else if (holder instanceof ViewHolderHeader) {
            //cast holder to VHHeader and set data for header.

            ((ViewHolder) holder).tv_items.setText(mainItems.get(i).geImgName());
            Log.d("####", "HEADER");
        }

您正在将ViewHolderHeader投射到ViewHolder

ViewHolderHeader无法在onBindViewHolder视图中强制转换

1 个答案: