ZipEntry.isDirectory（）和枚举 <? extends ZipEntry> 仅查看目录内容，而不查看目录

Question

I'm working on looking through a .zip file to confirm that all the contained files are named correctly, and running into some trouble. Here's the file hierarchy:

-.zip
  -dir
    -file1
    -file2
    -file3
  -file4
  -file5
  -file6

Code:

for (Enumeration<? extends ZipEntry> e = zf.entries(); e.hasMoreElements(); ) {
            ZipEntry entry = e.nextElement();
            System.out.println("ZipEntry name: " + entry.getName());
            ...
}

Usual output:

ZipEntry name: dir/file1
ZipEntry name: dir/file2
ZipEntry name: dir/file3
ZipEntry name: file4
ZipEntry name: file5
ZipEntry name: file6

The desired output would also contain

ZipEntry name: dir/

Strangely enough, I have one test case where I get the desired output: when using a .zip of identical hierarchy that was emailed to me. Whenever I use the .zips that I have compressed on my machine, I get the "Usual output." I'd really like to have consistent behavior, but I can't figure out what's going wrong. Any ideas?

Thanks in advance!

Answer 1

There aren't really directories in a zip file. There are entries. And ZipEntry#isDirectory() checks if the name of the entry ends with a / to determine if it should be considered a directory. So what your zip file contains is

dir/file1
dir/file2
dir/file3
file4
file5
file6

For that strange case, the zip probably actually contains

dir/   // the entry won't actually have any content though
dir/file1
dir/file2
dir/file3
file4
file5
file6

This is useful for zip file managers to determine how entries should be extracted.