有文件夾對象列表，我需要將它們連接到絕對路徑。每個文件夾都有字段“parentId”（可為空）和“orderNumber”，例如：class Folder {    folderId;    desc;    parentId;    orderNumber;}因此，如果 ParentId == null -> 文件夾是絕對路徑中的第一個文件夾，如果不是 -> 我們應該獲取父文件夾，依此類推。我就是這樣做的，也許有更簡單的方法？public static void main(String[] args) {        List<Folder> list = new ArrayList<Folder>();        list.add(new Folder(1, null, "root1"));        list.add(new Folder(3, 2, "child2"));        list.add(new Folder(2, 1, "child1"));        list.add(new Folder(5, 4, "child4"));        list.add(new Folder(6, null, "root2"));        list.add(new Folder(4, 3, "child3"));        Integer fromId = 5;        String path = getAbsolutePath(list, getFolderById(list, fromId));        System.out.println(path);    }    public static String getAbsolutePath(List<Folder> list, Folder folder) {        String path = "";        Integer parentId = folder.getParentId();        if (parentId != null) {            Folder parent = getFolderById(list, parentId);            path += getAbsolutePath(list, parent) + "/";        }        path += folder.getDesc();        return path;    }    public static Folder getFolderById(List<Folder> list, Integer folderId) {        return list.stream().filter(row -> row.getId() == folderId).findFirst().get();    }Output: root1/child1/child2/child3/child4更新：public static void main(String[] args) {        List<Folder> list = new ArrayList<Folder>();        list.add(new Folder(1, null, "root1"));        list.add(new Folder(3, 2, "child2"));        list.add(new Folder(2, 1, "child1"));        list.add(new Folder(5, 4, "child4"));        list.add(new Folder(6, null, "root2"));        list.add(new Folder(4, 3, "child3"));        Map<Integer, Folder> folderMap = list.stream().collect(Collectors.toMap(                Folder::getId, folder -> folder        ));        Integer fromId = 5;        String path = getAbsolutePath(folderMap, folderMap.get(fromId));        System.out.println(path);    }