Java 片段中初始化为空的ViewHolder字段

我正在尝试使用大量“grid_cell”xml布局在回收器视图中设置gridLayout，每个布局包含5个ImageView。我让recyclerView工作得很好，直到我重新构造代码以适应数据库

问题是MapViewHolder构造函数中的所有ImageView都被初始化为null，导致

java.lang.NullPointerException:尝试在null对象引用上调用虚拟方法'void android.widget.ImageView.setImageResource（int）

公共类MapFragment扩展了片段
{
私有游戏数据存储游戏数据存储；
私人回收车；
私有映射适配器；
专用GridLayoutManager GridLayoutManager；
创建时的公共void（Bundle savedInstanceState）
{
super.onCreate（savedInstanceState）；
gameDataStorage=（（子应用程序）getActivity（）.getApplication（））.gameDataStorage；
}
@凌驾
创建视图上的公共视图（布局、扁平充气器、视图组父视图、捆绑包）
{
//从fragment_map.xml布局中展开视图。
视图=充气机。充气（R.layout.fragment\u map，父项，false）；
//从map_recycler_view.xml布局包装回收器视图
rv=view.findViewById（R.id.map\u recycler\u视图）；
adapter=新映射适配器（）；
//初始化网格布局管理器
gridLayoutManager=新建gridLayoutManager（getActivity（），GameData.getInstance（）.getSettings（）.getMapHeight（），gridLayoutManager.HORIZONTAL，false）；
//设置回收器视图适配器
rv.设置适配器（适配器）；
//将布局管理器设置为水平滚动网格
rv.setLayoutManager（gridLayoutManager）；
返回视图；
}
公共类MapViewHolder扩展了RecyclerView.ViewHolder
{
私有图像视图结构；
私有图像视图左上角；
私有图像视图右上角；
私有图像视图左下角；
私权；
公共地图视图持有者（Layoutiner li，视图组父级）
{
super（li.inflate（R.layout.grid_单元格，父单元格，false））；
int size=parent.getMeasuredHeight（）/GameData.getInstance（）.getSettings（）.getMapHeight（）+1；
ViewGroup.LayoutParams lp=parent.getLayoutParams（）；
lp.高度=尺寸；
lp.宽度=尺寸；
structure=（ImageView）parent.findViewById（R.id.structure）；
topLeft=（ImageView）parent.findViewById（R.id.top\u left）；
topRight=（ImageView）parent.findViewById（R.id.top\u right）；
bottomLeft=（ImageView）parent.findViewById（R.id.bottom\u left）；
bottomRight=（ImageView）parent.findViewById（R.id.bottom\u right）；
//调试
Log.d（“游戏数据”，“结构参考被初始化为”+结构）；
Log.d（“游戏数据”，“左上角参考初始化为“+左上角”）；
Log.d（“游戏数据”，“右上角参考被初始化为“+右上角”）；
Log.d（“游戏数据”，“左下角参考被初始化为“+左下角”）；
Log.d（“游戏数据”，“右下角参考被初始化为“+右下角”）；
}
公共void绑定（最终MapElement元素，最终int索引）
{
if（element.getStructure（）！=null）{
setImageResource（element.getStructure（）.getImageId（））；
}
其他的
{
if（结构==null）
{
Log.d（“游戏_数据”，“mapElement的结构引用为空”+索引）；
}
setImageResource（GameData.getInstance（）.getEmpty（））；
}
setImageResource（element.getTopLeft（））；
setImageResource（element.getTopRight（））；
setImageResource（element.getBottomLeft（））；
setImageResource（element.getBottomRight（））；
structure.setOnClickListener（新视图.OnClickListener（）{
@凌驾
公共void onClick（视图v）
{
int row=索引%GameData.getInstance（）.getSettings（）.getMapHeight（）；
int col=index/GameData.getInstance（）.getSettings（）.getMapHeight（）；
StructureData.setStructureAt（行、列）；
gameDataStorage.updateMapElement（元素，元素.getStructure（），索引）；
adapter.notifyItemChanged（索引）；
}
});
structure.setOnLongClickListener（新视图.OnLongClickListener（）{
@凌驾
仅长按公共布尔值（视图v）{
返回false；
}
});
}
}
//端部包括（RecyclerViewSampleWilder）
公共类MapAdapter扩展了RecyclerView.Adapter
{
//开始包括（RecycleServiceOnCreateViewHolder）
//创建新视图（由布局管理器调用）
@凌驾
public MapViewHolder onCreateViewHolder（视图组容器，int-viewType）
{
Log.d（“游戏_数据”，“使用ViewGroup“+容器+”和viewType“+视图类型”的新地图视图持有者）；
返回新的MapViewHolder（LayoutInflater.from（getActivity（）），容器）；
}
//END_包括（RecycleServiceOnCreateViewHolder）
//开始包括（RecycleServiceOnBindViewHolder）
//替换视图的内容（由布局管理器调用）
@凌驾
BindViewHolder上的公共无效（MapViewHolder vh，内部索引）{
//在此位置从数据集中获取元素并替换视图的内容
//有了这个元素
int row=索引%GameData.getInstance（）.getSettings（）.getMapHeight（）；
int col=index/GameData.getInstance（）.getSettings（）.getMapHeight（）；
MapElement=GameDat
public class MapFragment extends Fragment
{
    private GameDataStorage gameDataStorage;
    private RecyclerView rv;
    private MapAdapter adapter;
    private GridLayoutManager gridLayoutManager;

    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        gameDataStorage = ((SubApplication)getActivity().getApplication()).gameDataStorage;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle bundle)
    {
        //Inflate the view from fragment_map.xml layout.
        View view = inflater.inflate(R.layout.fragment_map, parent, false);

        //Crate the recycler view from the map_recycler_view.xml layout
        rv = view.findViewById(R.id.map_recycler_view);

        adapter = new MapAdapter();

        //Initialise the grid layout manager
        gridLayoutManager = new GridLayoutManager(getActivity(), GameData.getInstance().getSettings().getMapHeight(), GridLayoutManager.HORIZONTAL, false);

        //Set the recycler view adapter
        rv.setAdapter(adapter);

        //Set the layout manager to be a horizontal scrolling grid
        rv.setLayoutManager(gridLayoutManager);

        return view;
    }

    public class MapViewHolder extends RecyclerView.ViewHolder
    {
        private ImageView structure;
        private ImageView topLeft;
        private ImageView topRight;
        private ImageView bottomLeft;
        private ImageView bottomRight;

        public MapViewHolder(LayoutInflater li, ViewGroup parent)
        {
            super(li.inflate(R.layout.grid_cell, parent, false));

            int size = parent.getMeasuredHeight() / GameData.getInstance().getSettings().getMapHeight() + 1;
            ViewGroup.LayoutParams lp = parent.getLayoutParams();
            lp.height = size;
            lp.width = size;

            structure = (ImageView) parent.findViewById(R.id.structure);
            topLeft = (ImageView) parent.findViewById(R.id.top_left);
            topRight = (ImageView) parent.findViewById(R.id.top_right);
            bottomLeft = (ImageView) parent.findViewById(R.id.bottom_left);
            bottomRight = (ImageView) parent.findViewById(R.id.bottom_right);

            //DEBUGGING
            Log.d("GAME_DATA", "structure reference is initialised as " + structure);
            Log.d("GAME_DATA", "topLeft reference is initialised as " + topLeft);
            Log.d("GAME_DATA", "topRight reference is initialised as " + topRight);
            Log.d("GAME_DATA", "bottomLeft reference is initialised as " + bottomLeft);
            Log.d("GAME_DATA", "bottomRight reference is initialised as " + bottomRight);
        }

        public void bind(final MapElement element, final int index)
        {
            if(element.getStructure() != null){
                structure.setImageResource(element.getStructure().getImageId());
            }
            else
            {
                if(structure == null)
                {
                    Log.d("GAME_DATA", "structure reference is null for mapElement " + index);
                }

                structure.setImageResource(GameData.getInstance().getEmpty());
            }
            topLeft.setImageResource(element.getTopLeft());
            topRight.setImageResource(element.getTopRight());
            bottomLeft.setImageResource(element.getBottomLeft());
            bottomRight.setImageResource(element.getBottomRight());

            structure.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v)
                {
                    int row = index % GameData.getInstance().getSettings().getMapHeight();
                    int col = index / GameData.getInstance().getSettings().getMapHeight();
                    StructureData.setStructureAt(row, col);

                    gameDataStorage.updateMapElement(element, element.getStructure(), index);

                    adapter.notifyItemChanged(index);
                }
            });

            structure.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View v) {
                    return false;
                }
            });
        }
    }
    // END_INCLUDE(recyclerViewSampleViewHolder)

    public class MapAdapter extends RecyclerView.Adapter<MapViewHolder>
    {
        // BEGIN_INCLUDE(recyclerViewOnCreateViewHolder)
        // Create new views (invoked by the layout manager)
        @Override
        public MapViewHolder onCreateViewHolder(ViewGroup container, int viewType)
        {
            Log.d("GAME_DATA", "new MapViewHolder using ViewGroup " + container + " and viewType " + viewType);
            return new MapViewHolder(LayoutInflater.from(getActivity()), container);
        }
        // END_INCLUDE(recyclerViewOnCreateViewHolder)

        // BEGIN_INCLUDE(recyclerViewOnBindViewHolder)
        // Replace the contents of a view (invoked by the layout manager)
        @Override
        public void onBindViewHolder(MapViewHolder vh, int index) {
            // Get element from your dataset at this position and replace the contents of the view
            // with that element
            int row = index % GameData.getInstance().getSettings().getMapHeight();
            int col = index / GameData.getInstance().getSettings().getMapHeight();
            MapElement element = GameData.getInstance().getMapLoc(row, col);

            vh.bind(element, index);
        }
        // END_INCLUDE(recyclerViewOnBindViewHolder)



        // Return the size of your dataset (invoked by the layout manager)
        @Override
        public int getItemCount() {
            int rows = GameData.getInstance().getMap().length;
            int cols = GameData.getInstance().getMap()[0].length;
            int length = rows * cols;
            Log.d("GAME_DATA", "getItemCount returns: " + length);
            return length;
        }
    }
}

public MapViewHolder(LayoutInflater li, ViewGroup parent)
    {
        final View = li.inflate(R.layout.grid_cell, parent, false);
        super(view);

        int size = view.getMeasuredHeight() / GameData.getInstance().getSettings().getMapHeight() + 1;
        ViewGroup.LayoutParams lp = view.getLayoutParams();
        lp.height = size;
        lp.width = size;

        structure = (ImageView) view.findViewById(R.id.structure);
        topLeft = (ImageView) view.findViewById(R.id.top_left);
        topRight = (ImageView) view.findViewById(R.id.top_right);
        bottomLeft = (ImageView) view.findViewById(R.id.bottom_left);
        bottomRight = (ImageView) view.findViewById(R.id.bottom_right);

        //DEBUGGING
        Log.d("GAME_DATA", "structure reference is initialised as " + structure);
        Log.d("GAME_DATA", "topLeft reference is initialised as " + topLeft);
        Log.d("GAME_DATA", "topRight reference is initialised as " + topRight);
        Log.d("GAME_DATA", "bottomLeft reference is initialised as " + bottomLeft);
        Log.d("GAME_DATA", "bottomRight reference is initialised as " + bottomRight);
    }

    public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.Holder> {
    private final List<Model> list;

    RecyclerViewAdapter(List<WorkshopObj> data, EditTextChangeWorkshopListener editTextChangeWorkshopListener) {
        list = data;

        setHasStableIds(true);
    }

    @NotNull
    @Override
    public Holder onCreateViewHolder(ViewGroup parent, int viewType) {
        return new Holder(LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_workshop_adapter, parent, false));
    }

    @Override
    public void onBindViewHolder(final Holder holder, final int position) {

        final WorkshopObj model = list.get(position);

        holder.titleWorkshop.setText(model.getTitleText());
        holder.requiredWorkshop.setVisibility(model.isRequired() ? View.VISIBLE : View.GONE);
        holder.subTitle.setVisibility(model.isMandatory() ? View.VISIBLE : View.GONE);

    }

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

    class Holder extends RecyclerView.ViewHolder {

        private final TextView requiredWorkshop;
        private final TextView titleWorkshop;
        private final TextView subTitle;
        private final EditText price;

        Holder(View view) {
            super(view);
            requiredWorkshop = view.findViewById(R.id.required_workshop);
            titleWorkshop = view.findViewById(R.id.title_workshop);
            subTitle = view.findViewById(R.id.sub_title);
            price = view.findViewById(R.id.price);
        }
    }
}