将项添加到列表时出现NullPointerException

Question

Helo All，

当我想向List添加项目时，我遇到了一个问题，即我面临NullPointerException，如下所示：

public List<SearchResponse> sortMPGListViewForNA(List<SearchResponse> response)
    {
        List<SearchResponse> list = response;
        List<SearchResponse> tempMPG = null, tempPrice = null, tempRating = null;
        for(int i=0;i<response.size();i++)
        {
            if(response.get(i).years.get(0).mpg.equalsIgnoreCase("n/a"))
            {
                tempMPG.add(response.get(i));
                list.remove(i);
            }
            if(response.get(i).years.get(0).price.equalsIgnoreCase("n/a"))
            {
                tempPrice.add(response.get(i));
                list.remove(i);
            }
            if(response.get(i).years.get(0).rating.equalsIgnoreCase("n/a"))
            {
                tempRating.add(response.get(i));//NPE Occurs Here
                list.remove(i);
            }
        }
        response.addAll(tempMPG);
        response.addAll(tempPrice);
        response.addAll(tempRating);
        return response;
    }

请建议我解决方法。

提前致谢。

Answer 1

您需要初始化tempMPG，tempPrice和tempRating：

tempMpg = new ArrayList<SearchResponse>();
tempPrice = new ArrayList<SearchResponse>();
tempRating = new ArrayList<SearchResponse>();