Listing files inside a JAR

Java 2D
#1

Hi all. Not sure where else to post this… so this seemed the best place.

Anyway. What I need to to do here is list files from a directory called “images” inside a JAR file. Whenever I didn’t have my application in a JAR, I used the following:

File list[] = (new File("images")).listFiles(filter);

(filter is my FileFilter to return only PNG images)

However, I can’t use new File(“images”) in a JAR because it would just think I’m trying to access the directory outside the JAR. So I need to somehow create a File from this URL:

URL dir = Thread.currentThread().getContextClassLoader().getResource("images");

And I obviously need a File object because nothing else has the method listFiles() (that I know of). I’ve spent the last hour searching and trying everything I know. I even tried using the following:

URL dir = Thread.currentThread().getContextClassLoader().getResource("images");
File list[] = (new File(URI.create(dir.toString()))).listFiles(filter);

But it tells me that it’s not hierarchical. What can I do here?

Thanks,
Jamison

#2 

URL dir = Thread.currentThread().getContextClassLoader().getResource("images");
File file = new File(dir.toURI());

Enjoy :slight_smile:

#3

I tried that. But what I just realized here is that toURI() was not introduced until Java 1.5… and I’m compiling with 1.4 (however I have the 1.5 and 1.6 JRE) but I also have the Java 1.6 JDK too.

OK, so anyway. I got 1.5 JDK now. I compile it, no errors, except depreciation warnings (why?). But I get a runtime error:

#
# An unexpected error has been detected by HotSpot Virtual Machine:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x6d1279f7, pid=5504, tid=2360
#
# Java VM: Java HotSpot(TM) Client VM (1.5.0_10-b03 mixed mode, sharing)
# Problematic frame:
# C  [awt.dll+0xb79f7]
#
# An error report file with more information is saved as hs_err_pid5504.log
#
# If you would like to submit a bug report, please visit:
#   http://java.sun.com/webapps/bugreport/crash.jsp
#
#4

Why? You build the JAR file, so you already know what files are going to be there. If you don’t want to include a list of a lot of files in your code, just create a text or XML file with the list in it that you can read at run time.

#5

That’s true, but I kinda wanted to simplify the process. I guess if I must, I’ll use that then. I just didn’t want to countinously update the file list. But oh well.

#6

This seems like the kind of thing you could coax ant into doing automagically whenever you build your jars.

#7

You can always treat the JAR as an Zip file and use the java Zip methods to go through the files in the JAR.

something along the lines of:


ZipInputStream zipin=Thread.currentThread().getContextClassLoader().getResource("<< YOUR JAR FILE >>")..openStream();
ZipEntry zipEntry=zipin.nextEntry();
List fileNames=new ArrayList();
while (zipEntry!=null)
{
  String name=  zipEntry.getName());
  if (name.startsWith("images") fileNames.add(name);
  zipEntry=zipin.nextEntry();
}
#8

moogie, I have quite a few files so it’d be pretty darn slow. But anyway, I used CaptainJester’s idea to use a filelist text file. Works a little better and obviously faster loading.