Java: How to create a directory in a zip using java.nio.file.FileSystem

Question

I've followed what this page has told me but I can't get it to work. I want it so that in my test.zip a folder called "new" will be in there. Whenever I run the code below it gives a FileAlreadyExistsException and only creates an empty zip file.

    Map<String, String> env = new HashMap<>();
    env.put("create", "true");
    Path path = Paths.get("test.zip");
    URI uri = URI.create("jar:" + path.toUri());
    try (FileSystem fs = FileSystems.newFileSystem(uri, env)) {
        Path nf = fs.getPath("new/");
        Files.createDirectory(path);

    } catch (IOException e) {
        e.printStackTrace();
    }

Answer 1

Because Files.createDirectory() states in the javadoc

throws FileAlreadyExistsException - if dir exists but is not a directory (optional specific exception)

you need to check if the folder already exits:

try (FileSystem fs = FileSystems.newFileSystem(uri, env)) {
    Path nf = fs.getPath("new");
    if (Files.notExists(nf)) {
        Files.createDirectory(nf);
    }
}

Answer 2

Have you tried java.util.zip.ZipEntry ?

FileOutputStream f = new FileOutputStream("test.zip");
ZipOutputStream zip = new ZipOutputStream(new BufferedOutputStream(f));
zip.putNextEntry(new ZipEntry("new/"));