GridView NullPointerException

Question

我哪里错了？ 为什么这个空指针异常

    private class GridAdapter extends BaseAdapter {
    private LayoutInflater inflater;

    public GridAdapter(Context context) {
        Logger.d(TAG, "GridAdapter");
        inflater = LayoutInflater.from(context);
    }

    @Override
    public int getCount() {
        Logger.d("SIZE",""+AppConstants.getMenuList().size());
        return AppConstants.getMenuList().size();
    }

    @Override
    public Object getItem(int i) {
        return AppConstants.getMenuList().get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    class ViewHolder {
        TextView title;
        RelativeLayout layout;
        ImageView image;
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        View view;
        if (convertView == null) {
            view = inflater.inflate(R.layout.inflater_grid_layout, null);
            ViewHolder viewHolder = new ViewHolder();
            viewHolder.layout = (RelativeLayout) view.findViewById(R.id.igl_layout);
            viewHolder.title = (TextView) view.findViewById(R.id.igl_name);
            viewHolder.image = (ImageView) view.findViewById(R.id.igl_image);
            view.setTag(viewHolder);
        } else {
            view = convertView;
        }
        final ViewHolder holder = (ViewHolder) view.getTag();
        MenuModel item = (MenuModel) getItem(position);
        holder.layout.setBackgroundColor(item.getColor());      //NULL POINTER HERE
        holder.title.setText(item.getName());
        holder.image.setImageResource(item.getImage());
        return view;
    }
}

这是我的LogCat：

显示java.lang.NullPointerException         在in.abm.indiape.fragments.GridMenuScreen $ GridAdapter.getView（GridMenuScreen.java:115）         在android.widget.AbsListView.obtainView（AbsListView.java:2624）         在android.widget.GridView.onMeasure（GridView.java:1045）         在android.view.View.measure（View.java:16831）         在android.widget.RelativeLayout.measureChildHorizo​​ntal（RelativeLayout.java:728）         在android.widget.RelativeLayout.onMeasure（RelativeLayout.java:477）         在android.view.View.measure（View.java:16831）

Answer 1

您setTag不能查看convertView。在else部分，您有view = convertView;。

然后你有view.getTag()当convertView不为null时，可能会返回null，如prosper k所示。

您无需使用View view即可直接使用convertView。

所以将getView更改为

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
     ViewHolder viewHolder;
    if (convertView == null) {
        convertView= inflater.inflate(R.layout.inflater_grid_layout, null);
        viewHolder = new ViewHolder();
        viewHolder.layout = (RelativeLayout) convertView.findViewById(R.id.igl_layout);
        viewHolder.title = (TextView) convertView.findViewById(R.id.igl_name);
        viewHolder.image = (ImageView) convertView.findViewById(R.id.igl_image);
        convertView.setTag(viewHolder); // setTag if convertView is null
    } else {
        viewHolder = (ViewHolder)convertView.getTag();
        // get tag if convertView is not null
    }

    MenuModel item = (MenuModel) getItem(position);
    // update ui elements 
    viewHolder.layout.setBackgroundColor(item.getColor());      
    viewHolder.title.setText(item.getName());
    viewHolder.image.setImageResource(item.getImage());
    return convertView;
}