java - 我的逻辑有什么问题

Question

我有一个自定义类的 ArrayList

public class DetailedData
{
    String Company;
    String Model;
    String Category;
    String ImageType;
    String ImageBuffer1;
    String ImageBuffer2;
}

这是我收到的一小部分数据样本，但大部分都遵循相同的模式。

dell, inspiron 15-R, laptop, Header, 9j4AAQSk, null
dell, inspiron 15-R, laptop, Thumbnail, iVBORw0KGg, null
apple, macbook air, laptop, Header, 9j4AAQSk, null
apple, macbook air, laptop, Thumbnail, iVBORw0KGg, null
dell, xps 13, laptop, Header, 9j4AAQSk, null

我想合并这些重复的数据并将其存储在像这样的新列表中

dell, inspiron 15-R, laptop, Header, 9j4AAQSk, iVBORw0KGg
apple, macbook air, laptop, Header, 9j4AAQSk, iVBORw0KGg
dell, xps 13, laptop, Header, 9j4AAQSk, null

但是我没有收到正确的输出

这是我的逻辑

 ArrayList<DetailedData> data=getList();
 ArrayList<DetailedData> temp = new ArrayList<>();
 for (int i = 0; i < data.size(); i++)
 {
    DetailedData currentData = data.get(i);
    if (temp.size() == 0)
    {
        temp.add(currentData);
    } else
    {
        for (int j = 0; j < temp.size(); j++)
        {
            DetailedData tempData = temp.get(j);
            if (tempData.Company.equals(currentData.Company))
            {
                if (tempData.ImageType.equals(currentData.ImageType))
                {}
                else
                {
                    temp.get(j).ImageBuffer2 = currentData.ImageBuffer1;
                }

            } else
            {
                temp.add(currentData);
            }       
        }
    }
} 

Answer 1

我找到了一个巧妙的方法，使用流:

List<DetailedData> data = getList();

List<DetailedData> temp = data.stream()
    .collect(Collectors.groupingBy(DetailedData::getModel))
    .values().stream()
    .map(DetailedData::merge)
    .collect(Collectors.toList());          

temp.forEach(System.out::println);

输出:

dell, xps 13, laptop, Header, 9j4AAQSk, null
dell, inspiron 15-R, laptop, Header, 9j4AAQSk, iVBORw0KGg
apple, macbook air, laptop, Header, 9j4AAQSk, iVBORw0KGg

其中 DetailedData::merge 是一种将 DetailedData 列表合并为 1 的方法。例如:

public static DetailedData merge(List<DetailedData> list) {
    if(list.isEmpty()) // Not possible after 'groupingBy'.
        return null;

    if(list.size() == 1)
        return list.get(0);

    // At least 2 elements:
    DetailedData ret = list.get(0);
    ret.ImageBuffer2 = list.get(1).ImageBuffer1;
    return ret;
}

参见 Full Code