排序文件列表

Question

How can I list the files of multiple directorys in Java?

That's what I've tried:

ArrayList<File> files = new ArrayList<File>();
for(int x = 0; x < directorys.length; x++) {
    if(directorys[x].isDirectory()) {
        files.addAll(Arrays.asList(directorys[x].listFiles(filter)));
    } 
}

That works kind of, but the problem is, that it doesn't bring the files into a fully alphabetic order.
It's than sth. like this: (first folder) 1, 3, 5, (second folder) 2, 4, 6 . But I'd like it to be like this: 1, 2, 3, 4, 5, 6 .
So I guess, what it does, is that it brings all the files of each folder into the correct order, but not all files together.
How could I achieve that?

Answer 1

您可以使用比较器进行排序：

files.sort((a,b)-> a.getName().compareTo(b.getName()));

Answer 2

您可以在循环后对文件列表进行排序，如下所示

files.sort(Comparator.comparing(File::getName));