Java nio, get all subfolders of some folder

Question

How could I get all subfolders of some folder? I would use JDK 8 and nio.

for example, for folder "Designs.ipj" method should return {"Workspace", "Library1"}

Thank you in advance!

You should edit your post and include the image in your question. Eventually external links become unavailable at some point and as such preventing future users to benefit from your question. — Andrej, Jul 08 '16 at 14:26
https://docs.oracle.com/javase/tutorial/essential/io/dirs.html#listdir — Fildor, Jul 08 '16 at 14:28

score 17 · Accepted Answer · answered Jul 08 '16 at 14:42

17

    List<Path> subfolder = Files.walk(folderPath, 1)
            .filter(Files::isDirectory)
            .collect(Collectors.toList());

it will contains folderPath and all subfolders in depth 1. If you need only subfolders, just add:

subfolders.remove(0);

answered Jul 08 '16 at 14:42

Wsl_F

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1

DirectoryStream paths = Files.newDirectoryStream(folder, entry -> Files.isDirectory(entry)); much shorter – lisyara May 18 '19 at 16:19

score -2 · Answer 2 · edited May 23 '17 at 12:08

You have to read all the items in a folder and filter out the directories, repeating this process as many times as needed.

To do this you could use listFiles()

File folder = new File("your/path");
Stack<File> stack = new Stack<File>();
Stack<File> folders = new Stack<File>();

stack.push(folder);
while(!stack.isEmpty())
    {
        File child = stack.pop();
        File[] listFiles = child.listFiles();
        folders.push(child);

        for(File file : listFiles)
        {
            if(file.isDirectory())
            {
                stack.push(file);
            }
        }            
    }

see Getting the filenames of all files in a folder A simple recursive function would also work, just make sure to be wary of infinite loops.

However I am a bit more partial to DirectoryStream. It allows you to create a filter so that you only add the items that fit your specifications.

DirectoryStream.Filter<Path> visibleFilter = new DirectoryStream.Filter<Path>()
{
    @Override
    public boolean accept(Path file)
    {
        try
        {
            return Files.isDirectory(file));
        }
        catch(IOException e)
        {
            e.printStackTrace();
        }

        return false;
}

try(DirectoryStream<Path> stream = Files.newDirectoryStream(directory.toPath(), visibleFilter))
{
    for(Path file : stream)
    {
        folders.push(child);
    }
}

Java nio, get all subfolders of some folder

2 Answers2