android - 添加多个回收 View 时，不可转换类型无法将 dataobjectholder 转换为 groupview 持有者

Question

好吧，我是 recyclerview 的新手，我在这里迷路了。我想在一个 Activity 中有 2 个(或更多)recyclerview。我的问题出在这部分代码中

    error: here inconvertable type cannot cast dataobjectholder to groupview holder

 case 2:
                GroupViewHolder groupviewHolder = (GroupViewHolder) holder; //here inconvertable type cannot cast dataobjectholder to groupview holder
                groupviewHolder.label1.setText(mDataset.get(position).getmText1());
                // holder.dateTime.setText(mDataset.get(position).getmText2());
                //  holder.imageView.setImageResource();
                Picasso.
                        with(mContext).
                        load("http://justedhak.com/funnyimages/uploaded_images563cd66b98a20.png")
                        .placeholder(R.drawable.error)
                        .fit()
                        .noFade()
                        .into(groupviewHolder.imageView1);
            break;
        }

这是我的完整代码

public class MyRecyclerViewAdapter extends RecyclerView
        .Adapter<MyRecyclerViewAdapter
        .DataObjectHolder> {
    Context mContext;
    private static String LOG_TAG = "MyRecyclerViewAdapter";
    private ArrayList<DataObject> mDataset;
    private static MyClickListener myClickListener;
    public MyRecyclerViewAdapter(Context context)
    {

        this.mContext =context;
    }

    )
    public static class GroupViewHolder extends RecyclerView.ViewHolder
                   {
        TextView label1;
        ImageView imageView1;

        // TextView dateTime;

        public GroupViewHolder(View itemView) {
            super(itemView);
            label1 = (TextView) itemView.findViewById(R.id.textView);
            // dateTime = (TextView) itemView.findViewById(R.id.textView2);
            imageView1 = (ImageView) itemView.findViewById(R.id.image);

           // itemView.setOnClickListener(this);
        }
                   }
    public static class DataObjectHolder extends RecyclerView.ViewHolder
            implements View
            .OnClickListener {
        TextView label;
        ImageView imageView;

       // TextView dateTime;

        public DataObjectHolder(View itemView) {
            super(itemView);
            label = (TextView) itemView.findViewById(R.id.textView);
           // dateTime = (TextView) itemView.findViewById(R.id.textView2);
             imageView = (ImageView) itemView.findViewById(R.id.image);

            itemView.setOnClickListener(this);
        }



        @Override
        public void onClick(View v) {
            myClickListener.onItemClick(getPosition(), v);
        }
    }

    public void setOnItemClickListener(MyClickListener myClickListener) {
        this.myClickListener = myClickListener;
    }

    public MyRecyclerViewAdapter(ArrayList<DataObject> myDataset) {
        mDataset = myDataset;
    }

    @Override
    public DataObjectHolder onCreateViewHolder(ViewGroup parent,
                                               int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.recyclerview_item, parent, false);

        DataObjectHolder dataObjectHolder = new DataObjectHolder(view);
        return dataObjectHolder;
    }
    @Override
    public int getItemViewType(int position)
    {
        return position==0? 1:2;
    }
    @Override
    public void onBindViewHolder(DataObjectHolder holder, int position) {
        switch(holder.getItemViewType())
        {
            case 1:
                holder.label.setText(mDataset.get(position).getmText1());
                // holder.dateTime.setText(mDataset.get(position).getmText2());
                //  holder.imageView.setImageResource();
                Picasso.
                        with(mContext).
                        load("http://justedhak.com/funnyimages/uploaded_images563cd66b98a20.png")
                        .placeholder(R.drawable.error)
                        .fit()
                        .noFade()
                        .into(holder.imageView);
            break;

            case 2:
                GroupViewHolder groupviewHolder = (GroupViewHolder) holder;
                groupviewHolder.label1.setText(mDataset.get(position).getmText1());
                // holder.dateTime.setText(mDataset.get(position).getmText2());
                //  holder.imageView.setImageResource();
                Picasso.
                        with(mContext).
                        load("http://justedhak.com/funnyimages/uploaded_images563cd66b98a20.png")
                        .placeholder(R.drawable.error)
                        .fit()
                        .noFade()
                        .into(groupviewHolder.imageView1);
            break;
        }

    }

    public void addItem(DataObject dataObj, int index) {
        mDataset.add(dataObj);
        notifyItemInserted(index);
    }

    public void deleteItem(int index) {
        mDataset.remove(index);
        notifyItemRemoved(index);
    }

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

    public interface MyClickListener {
        public void onItemClick(int position, View v);
    }

Answer 1

首先，你有两个不同的Viewholder，所以你的类extends RecyclerView.Adapter而不是 extends RecyclerView.Adapter<MyRecyclerViewAdapter.DataObjectHolder>

现在看看你的onCreateViewHolder功能:它只返回一种类型的Viewholder。应该是:

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent,
                                           int viewType) {
    if (viewType == 1) { 
        View view = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.recyclerview_item, parent, false);

        DataObjectHolder dataObjectHolder = new DataObjectHolder(view);
        return dataObjectHolder;
    } else {
        //TODO: Inflate view and return GroupViewHolder
    }
}

那么你的 onBindViewHolder 有错误功能:

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    switch(getItemViewType(position)) { 
       // TODO...
    }
}

或

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    if (holder instanceof DataObjectHolder) {
       // Do this...
    } else if (holder instanceof GroupViewHolder) {
       // ...do that
    }
}