Add an empty dir to a Zip file programmatically

Hi,
How do I add an empty dir to a Zip file programmatically

import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
....
try {
ZipEntry dirEntry = new ZipEntry(dirFile.getPath());
zipOutputStream.putNextEntry(dirEntry);
}
catch (IOException e) {}

The dir is added as an empty file

Please help

Covington Bradshaw

"Covington Bradshaw" <> wrote in message
news...
> Hi,
> How do I add an empty dir to a Zip file programmatically
>
> import java.util.zip.ZipEntry;
> import java.util.zip.ZipOutputStream;
> ...
> try {
> ZipEntry dirEntry = new ZipEntry(dirFile.getPath());
> zipOutputStream.putNextEntry(dirEntry);
> }
> catch (IOException e) {}
>
> The dir is added as an empty file
>
> Please help
>

I have a reasonable suspicion that a zip archive cannot contain an empty
directory entry.
You might be able to back this up with a more formal specification of the
zip archive format.

--
Tony Morris
(BInfTech, Cert 3 I.T.)
Software Engineer
(2003 VTR1000F)
Sun Certified Programmer for the Java 2 Platform (1.4)
Sun Certified Developer for the Java 2 Platform

or you can just try it, i did and it was
easy to create a zip file that contains only an empty directory
with zip


"Tony Morris" <> wrote in message
news:c4ii4q$9g6$...
>
> "Covington Bradshaw" <> wrote in message
> news...
> > Hi,
> > How do I add an empty dir to a Zip file programmatically
> >
> > import java.util.zip.ZipEntry;
> > import java.util.zip.ZipOutputStream;
> > ...
> > try {
> > ZipEntry dirEntry = new ZipEntry(dirFile.getPath());
> > zipOutputStream.putNextEntry(dirEntry);
> > }
> > catch (IOException e) {}
> >
> > The dir is added as an empty file
> >
> > Please help
> >
>
> I have a reasonable suspicion that a zip archive cannot contain an empty
> directory entry.
> You might be able to back this up with a more formal specification of the
> zip archive format.
>
> --
> Tony Morris
> (BInfTech, Cert 3 I.T.)
> Software Engineer
> (2003 VTR1000F)
> Sun Certified Programmer for the Java 2 Platform (1.4)
> Sun Certified Developer for the Java 2 Platform
>
>

"nos" <> wrote in message
news:M56bc.58157$K91.141189@attbi_s02...
> or you can just try it, i did and it was
> easy to create a zip file that contains only an empty directory
> with zip

I did try it with both Winzip and jar, hence the suspicion (and not the
conclusion).
What did you use to create teh archive ?


--
Tony Morris
(BInfTech, Cert 3 I.T.)
Software Engineer
(2003 VTR1000F)
Sun Certified Programmer for the Java 2 Platform (1.4)
Sun Certified Developer for the Java 2 Platform

On Thu, 01 Apr 2004 20:42:21 -0500, Covington Bradshaw wrote:

> How do I add an empty dir to a Zip file programmatically

I do not know if that is possible.
Why do you need it, there may be
better ways to achieve what you want.

--
Andrew Thompson
http://www.PhySci.org/ Open-source software suite
http://www.PhySci.org/codes/ Web & IT Help
http://www.1point1C.org/ Science & Technology

"Tony Morris" <> wrote in message
news:c4ira3$jge$...
>
> "nos" <> wrote in message
> news:M56bc.58157$K91.141189@attbi_s02...
> > or you can just try it, i did and it was
> > easy to create a zip file that contains only an empty directory
> > with zip
>
> I did try it with both Winzip and jar, hence the suspicion (and not the
> conclusion).
> What did you use to create teh archive ?
>

Here is my screen
-----------------------------------
C:\>mkdir sss

C:\>zip jones.zip sss
adding: sss/ (stored 0%)

C:\>unzip -t jones
Archive: jones.zip
testing: sss/ OK
No errors detected in compressed data of jones.zip.

-----------------------------------
> --
> Tony Morris
> (BInfTech, Cert 3 I.T.)
> Software Engineer
> (2003 VTR1000F)
> Sun Certified Programmer for the Java 2 Platform (1.4)
> Sun Certified Developer for the Java 2 Platform
>
>

On Fri, 2 Apr 2004 12:11:36 +1000, Tony Morris wrote:

> "Covington Bradshaw" <> wrote in message
....
>> How do I add an empty dir to a Zip file programmatically
...
> I have a reasonable suspicion that a zip archive cannot contain an empty
> directory entry.

My response was based on a (vague) memory
of trying to do just that, and failing.

(AFAIR, I was iterating through a directory
structure copying every file/directory to
a zip - only the 'non-empty' directories
made it)

> You might be able to back this up with a more formal specification of the
> zip archive format.

That is the best idea so far.

--
Andrew Thompson
http://www.PhySci.org/ Open-source software suite
http://www.PhySci.org/codes/ Web & IT Help
http://www.1point1C.org/ Science & Technology

Tony Morris wrote:

> "nos" <> wrote:
>
>> or you can just try it, i did and it was
>> easy to create a zip file that contains only an empty directory
>> with zip
>
> I did try it with both Winzip and jar, hence the suspicion (and not the
> conclusion).
> What did you use to create teh archive ?

The following is a uuencoded ZIP file containg
-1- an empty file
-2- an empty folder

You can uudecode it to retrieve EmptyTest.zip
and then you can use WinZip extract-all command
to retrieve
-1- EmptyTextDocument.txt an empty file
-2- EmptyTestFoleer an empty folder

- Dario

"nos" <> wrote in message
news:mW6bc.59224$JO3.37141@attbi_s04...
>
> "Tony Morris" <> wrote in message
> news:c4ira3$jge$...
> >
> > "nos" <> wrote in message
> > news:M56bc.58157$K91.141189@attbi_s02...
> > > or you can just try it, i did and it was
> > > easy to create a zip file that contains only an empty directory
> > > with zip
> >
> > I did try it with both Winzip and jar, hence the suspicion (and not the
> > conclusion).
> > What did you use to create teh archive ?
> >
>
> Here is my screen
> -----------------------------------
> C:\>mkdir sss
>
> C:\>zip jones.zip sss
> adding: sss/ (stored 0%)
>
> C:\>unzip -t jones
> Archive: jones.zip
> testing: sss/ OK
> No errors detected in compressed data of jones.zip.
>
> -----------------------------------

I just also tried to do the same thing with "jar"
and was not able to do it, so maybe that is a
feature of java to help you to not waste space.
You should be able to add an empty directory
to a jar file with zip however.

> > --
> > Tony Morris
> > (BInfTech, Cert 3 I.T.)
> > Software Engineer
> > (2003 VTR1000F)
> > Sun Certified Programmer for the Java 2 Platform (1.4)
> > Sun Certified Developer for the Java 2 Platform
> >
> >
>
>

Ok I found out!
The trick is to postpend /. to the directory name, or programmatically as
follows
System.getProperty("file.separator")+"."


import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
...
try { ZipEntry dirEntry = new
ZipEntry(dirFile.getPath()+System.getProperty("fil e.separator")+".");
zipOutputStream.putNextEntry(dirEntry);
}
catch (IOException e) {}

This adds an empty file with name "." of zero size, which stands for the
directory iself!