Question

我有一个对象列表。我想根据文件大小从arraylist制作子列表。

示例：

[{
        "name": "food_image1.jpeg",
        "fileSize": 10
    },
    {
        "name": "food_image2.jpeg",
        "fileSize": 20
    },
    {
        "name": "food_image3.jpeg",
        "fileSize": 30
    },
    {
        "name": "food_image4.jpeg",
        "fileSize": 10
    }
]

我的固定尺寸是：40;

所以我的子列表将是：

[
    [{
            "name": "food_image1.jpeg",
            "fileSize": 10
        },
        {
            "name": "food_image2.jpeg",
            "fileSize": 20
        },
        {
            "name": "food_image4.jpeg",
            "fileSize": 10
        }
    ],
    [{
        "name": "food_image3.jpeg",
        "fileSize": 30
    }]
]

所以，我有mojo对象 FileInfo.java 有两个属性

public class FileInfo{

    private String name;
    private Long fileSize;
 //setter and getters
}

我的逻辑是：

 public List<List<FileInfo>> getAllSublistFromList(){

        //fixed size data
        long fixedPartSize =40;
        long tempSize = 0;
        long finalSize = 0;

        //here I am fetching all the list
        List<FileInfo> fileInfoList = jsondataList();

        List<FileInfo> makeSublist = new ArrayList<>();

        //Initializing list of DriveFileInfo object within a list.
        List<List<FileInfo>> allDataAspart = new ArrayList<>();

        //iterating arraylist of DriveFileInfo object
        for (int i = fileInfoList.size() - 1; i >= 0; i--) {

                //first fetching filesize of every DriveFileInfo object

                tempSize = fileInfoList.get(i).getFileSize();

                //checking if the file exist or not

                if (tempSize >= 1) {

                    //if the file exist keep it as finalSize.

                    finalSize = finalSize + tempSize;

                    //now checking new size is greater than fixed size or not.

                    if (finalSize <= fixedPartSize) {

                        //if the finalSize is lessar than fixedSize then add to ArrayList,named makeSublist
                        makeSublist.add(fileInfoList.get(i));

                        //after adding to the list remove index from  makeSublist Arraylist
                        fileInfoList.remove(i);
                    } else {
                        finalSize = 0;

                        //if the finalSize is greater than fixedSize then add to ArrayList of Arraylist,named allDataAspart
                        allDataAspart.add(makeSublist);

                        //and clean the arraylist means initialize makeSublist arraylist data
                        makeSublist = new ArrayList<>();
                    }
                }

                //checking if the file not exist
                else {
                    //remove the index from fileInfoList arraylist
                    fileInfoList.remove(i);
                }
            }
            allDataAspart.add(makeSublist);

        //returning the arraylist of List object data.
        return allDataAspart;
    }

但是我没有从列表中获得正确的列表..当列表很长并且固定大小发生变化时，有些文件丢失..请帮助我们..

Answer 1

这个怎么样：

public List<List<FileInfo>> partition(List<FileInfo> list, int maxSize) {
    List<List<FileInfo>> result = new ArrayList<>();
    List<FileInfo> current = new ArrayList<>();
    int currentSize = 0;
    for (FileInfo fi: list) {
        if (fi.getFileSize() > 0) {
            if (!current.isEmpty()
                    && currentSize + fi.getFileSize() > maxSize) {
                result.add(current);
                current = new ArrayList<>();
                currentSize = 0;
            }
            current.add(fi);
            currentSize += fi.getFileSize();
        }
    }
    if (!current.isEmpty()) {
        result.add(current);
    }
    return result;
}

Java从数组列表中创建子列表并存储到对象列表的数组列表中

1 个答案: