java - 在多个 View 持有者 recyclerview 上转换异常

Question

我在DataListAdapter中使用了多个viewholder。每个支架都有一个适配器。

我的适配器:

public class DataListAdapter extends BaseAdapter<HomeListItem> {
    private RecyclerView.RecycledViewPool pool;
    public static final int ADS = 10, DATA = 11, PIC = 13, QUE=14;



    public DataListAdapter(ArrayList<HomeListItem> dataList, AdapterListener<HomeListItem> listener) {
        this.dataList = dataList;
        this.listener = listener;
        pool = new RecyclerView.RecycledViewPool();
    }



    @Override
    public void onViewRecycled(@NonNull BaseViewHolder holder) {
        super.onViewRecycled(holder);
    }

    @NonNull
    @Override
    public BaseViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        if (viewType == ADS){
            return new ADSDataHolder(LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.item_home_ads, parent, false));
        }else if (viewType == PIC) {
            return new PictureHolder(LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.list_item_home, parent, false));
        }else if (viewType == QUE) {
            return new QuestionHolder(LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.list_item_home, parent, false));
        }else
            return new DataHolder(LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.list_item_home, parent, false));

    }

    @Override
    public int getItemViewType(int position) {

        if (dataList.get(position).getType() == ContentType.ADS)
            return ADS;
        if (dataList.get(position).getType() == ContentType.GALLERY)
            return PIC;
        if (dataList.get(position).getType() == ContentType.LIBS )
            return DATA;

        return QUE;
    }

    @Override
    public void onBindViewHolder(@NonNull BaseViewHolder holder, int position) {
             if (holder instanceof DataHolder){
                 ((DataHolder) holder).bind(dataList.get(position));
            } else if (holder instanceof ADSDataHolder) {
                ((ADSDataHolder) holder).bind(dataList.get(position));
            } else if (holder instanceof PictureHolder) {
                ((PictureHolder) holder).bind(dataList.get(position));
            }else if (holder instanceof QuestionHolder) {
                ((QuestionHolder) holder).bind(dataList.get(position));
            }
    }

    class ADSDataHolder extends BaseViewHolder {
        ...
    }

    class PictureHolder extends BaseViewHolder {
         ...
    }


    class QuestionHolder extends BaseViewHolder{
        private RecyclerView recyclerView;
        private TextView title;
        private View more;
        public QuestionHolder(View itemView) {
            super(itemView);
            setType(QUE);

            more = itemView.findViewById(R.id.more);
            title = itemView.findViewById(R.id.title);
            recyclerView = itemView.findViewById(R.id.recyclerView);
            recyclerView.setLayoutManager(new LinearLayoutManager(itemView.getContext(),RecyclerView.HORIZONTAL,false));
            recyclerView.hasFixedSize();
            recyclerView.setRecycledViewPool(pool);
        }
        public void bind(HomeListItem data) {
            Collections.reverse(data.getData());
            title.setText(data.getType().getVisibleName());
            HomeQuestionAdapter adapter = new HomeQuestionAdapter((ArrayList<MainPageItem>) (ArrayList<?>) data.getData(),
                    new AdapterListener<MainPageItem>() {
                        @Override
                        public void onItemClick(MainPageItem item) {
                            onListItemClick(itemView.getContext(), data.getType(), item.getItemId());
                        }
                    });
            recyclerView.setAdapter(adapter);
            more.setOnClickListener(v -> listener.onItemClick(data));
        }
    }
    class DataHolder extends BaseViewHolder {

        private RecyclerView recyclerView;
        private TextView title;
        private View more;

        DataHolder(View itemView) {
            super(itemView);
            setType(DATA);

            more = itemView.findViewById(R.id.more);
            title = itemView.findViewById(R.id.title);
            recyclerView = itemView.findViewById(R.id.recyclerView);
            recyclerView.setLayoutManager(new LinearLayoutManager(itemView.getContext(),
                    LinearLayoutManager.HORIZONTAL, true));
            recyclerView.hasFixedSize();
            recyclerView.setRecycledViewPool(pool);
        }

        public void bind(HomeListItem data) {
            Collections.reverse(data.getData());
            title.setText(data.getType().getVisibleName());
            SmallItemAdapter adapter = new SmallItemAdapter((ArrayList<MainPageItem>)
                    (ArrayList<?>) data.getData(),
                    new AdapterListener<MainPageItem>() {
                        @Override
                        public void onItemClick(MainPageItem item) {
                            onListItemClick(itemView.getContext(), data.getType(), item.getItemId());
                        }
                    });
            recyclerView.setAdapter(adapter);
            recyclerView.scrollToPosition(data.getData().size() - 1);
            more.setOnClickListener(v -> listener.onItemClick(data));
        }
    }

    private void onListItemClick(Context context, ContentType contentType, long id) {
         // click
    }


}

基础适配器:

public abstract class BaseAdapter<T> extends RecyclerView.Adapter<BaseViewHolder> {
    protected List<T> dataList;
    protected final int DATA_TYPE = 1;
    protected boolean isLoading = false, isMoreDataAvailable = false;
    protected AdapterListener<T> listener;

    @Override
    public int getItemViewType(int position) {
        if (dataList.get(position) == null)
            return -1;
        else return DATA_TYPE;
    }

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

    public void setMoreDataAvailable(boolean isMoreDataAvailable) {
        this.isMoreDataAvailable = isMoreDataAvailable;
    }

    public void removeLoadingItem() {
        if (dataList.size() > 0 && dataList.get(dataList.size() - 1) == null) {
            dataList.remove(dataList.size() - 1);
            notifyItemRemoved(dataList.size() - 1);
        }
    }

    public void notifyDataChanged() {
        isLoading = false;
        notifyDataSetChanged();
    }
}

和BaseViewHolder:

public class BaseViewHolder extends RecyclerView.ViewHolder {
    private int type;
    public BaseViewHolder(View itemView) {
        super(itemView);
    }
}

当我滚动 recyclerview 时出现错误

我的错误:

:00:26.247 4194-4194/ir.hnfadak.shahidezendeh E/PushPole:Exception caught 
    java.lang.ClassCastException: ir.hfadak.fadakmedia.UI.Main.Home.Picture.SmallItemAdapter$DataHolder cannot be cast to ir.hfadak.fadakmedia.UI.Main.Question.HomeQuestionAdapter$DataQueHolder
        at ir.hfadak.fadakmedia.UI.Main.Question.HomeQuestionAdapter.onBindViewHolder(HomeQuestionAdapter.java:31)
        at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7065)
        at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:7107)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:6012)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6279)
        at androidx.recyclerview.widget.GapWorker.prefetchPositionWithDeadline(GapWorker.java:288)
        at androidx.recyclerview.widget.GapWorker.flushTaskWithDeadline(GapWorker.java:345)
        at androidx.recyclerview.widget.GapWorker.flushTasksWithDeadline(GapWorker.java:361)
        at androidx.recyclerview.widget.GapWorker.prefetch(GapWorker.java:368)
        at androidx.recyclerview.widget.GapWorker.run(GapWorker.java:399)
        at android.os.Handler.handleCallback(Handler.java:754)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:163)
        at android.app.ActivityThread.main(ActivityThread.java:6238)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:933)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)

和我的 HomeQuestionAdapter

public class HomeQuestionAdapter extends RecyclerView.Adapter<HomeQuestionAdapter.DataQueHolder> {

    private RoundedCorners roundedCorners;
    protected List<MainPageItem> dataList;
    protected final int DATA_TYPE = 1;
    protected boolean isLoading = false, isMoreDataAvailable = false;
    protected AdapterListener<MainPageItem> listener;


    public HomeQuestionAdapter(ArrayList<MainPageItem> dataList, AdapterListener<MainPageItem> listener) {
        this.dataList = dataList;
        this.listener = listener;
        roundedCorners = new RoundedCorners(16);
    }



    @Override
    public int getItemViewType(int position) {
        if (dataList.get(position) == null)
            return -1;
        else return DATA_TYPE;
    }

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

    public void setMoreDataAvailable(boolean isMoreDataAvailable) {
        this.isMoreDataAvailable = isMoreDataAvailable;
    }

    public void removeLoadingItem() {
        if (dataList.size() > 0 && dataList.get(dataList.size() - 1) == null) {
            dataList.remove(dataList.size() - 1);
            notifyItemRemoved(dataList.size() - 1);
        }
    }

    public void notifyDataChanged() {
        isLoading = false;
        notifyDataSetChanged();
    }





    @NonNull
    @Override
    public HomeQuestionAdapter.DataQueHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            return new DataQueHolder(LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.item_list_simple_question, parent, false));
    }


    @Override
    public void onBindViewHolder(@NonNull HomeQuestionAdapter.DataQueHolder holder, int position) {
        if (!isLoading && isMoreDataAvailable && position >= getItemCount() - 1) {
            isLoading = true;
            listener.onLoadMore();
        } else {
             holder.bind(dataList.get(position));
        }
    }


    class DataQueHolder extends RecyclerView.ViewHolder {
        private ImageView image;
        private ImageView share,faivorid;
        private TextView question,answer,view;

        DataQueHolder(View itemView) {
            super(itemView);
            image = itemView.findViewById(R.id.imageQue);
            question = itemView.findViewById(R.id.titleQue);
            answer = itemView.findViewById(R.id.answerQue);
            share = itemView.findViewById(R.id.share);
            faivorid = itemView.findViewById(R.id.favorite);
            view = itemView.findViewById(R.id.viewtxt);

        }

        void bind(MainPageItem data) {
            Glide.with(itemView)
                    .load(data.getItemSmallImageAddress())
                    .apply(bitmapTransform(roundedCorners))
                    .apply(new RequestOptions().error(R.drawable.img_list_def)
                            .placeholder(R.drawable.img_list_def))
                    .into(image);
            question.setText(data.getItemTitle());
            answer.setText(data.getItemDescription());
            share.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    ContextUtil.share(itemView.getContext(),
                            data.getItemTitle() + "\n\n"
                                    + data.getItemDescription() + "\n\n"
                                    + data.getItemSmallImageAddress());
                }
            });


            itemView.setOnClickListener(v -> listener.onItemClick(data));
        }
    }
}

代码哪里错了？

Answer 1

您正在将父类(super class)的实例类型转换为导致此错误的子类的引用。

而是创建这样的东西:-

public void onBindViewHolder(@NonNull BaseViewHolder holder, int position) {
             if (holder instanceof DataQueHolder){
                 ((DataQueHolder) holder).bind(dataList.get(position));
            }else if (holder instanceof DataHolder){
                 ((DataHolder) holder).bind(dataList.get(position));
            }else if (holder instanceof ADSDataHolder) {
                ((ADSDataHolder) holder).bind(dataList.get(position));
            } else if (holder instanceof PictureHolder) {
                ((PictureHolder) holder).bind(dataList.get(position));
            }else if (holder instanceof QuestionHolder) {
                ((QuestionHolder) holder).bind(dataList.get(position));
            }
    }