Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!goblin3!goblin.stu.neva.ru!newsfeed2.funet.fi!newsfeeds.funet.fi!uio.no!ntnu.no!not-for-mail
From: Bent C Dalager <bcd@pvv.ntnu.no>
Newsgroups: comp.lang.java.programmer
Subject: Re: CLI Java Glitch
Date: Fri, 24 Jun 2011 22:49:40 +0000 (UTC)
Organization: Norwegian university of science and technology
Lines: 55
Message-ID: <slrnj0a544.64t.bcd@microbel.pvv.ntnu.no>
References: <meevv65a675khs5c9goa9sp6f2hotf1321@4ax.com> <itogee$k8r$1@localhost.localdomain> <4dffe2ea$0$57121$c30e37c6@exi-reader.telstra.net> <alpine.DEB.2.00.1106212245430.6476@urchin.earth.li> <TL-dnR5jfceDipzTnZ2dnUVZ_t6dnZ2d@posted.palinacquisition> <itvq8g82avs@news2.newsguy.com> <caf4475a-03ef-444b-8eba-9899232227d4@l14g2000pro.googlegroups.com>
NNTP-Posting-Host: microbel.pvv.ntnu.no
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-Trace: orkan.itea.ntnu.no 1308955780 1209 129.241.210.179 (24 Jun 2011 22:49:40 GMT)
X-Complaints-To: usenet@ntnu.no
NNTP-Posting-Date: Fri, 24 Jun 2011 22:49:40 +0000 (UTC)
User-Agent: slrn/pre1.0.0-18 (Linux)
Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:5658

The below program creates two distinct files on the file system of my
OSX 10.6.7, one with a regular hyphen and one with the non-breaking
hyphen. Other OS/FS combinations may behave differently. Of course,
the two files look exactly the same. In my opinion this is a lot more
subtle than a case difference and just underscores that string
comparison is a very complicated topic. (This particular sort of
subtelty used to be phishing gold, but I believe browser vendors have
since implemented countermeasures against that.)

I can't offhand think of any characters that are legal in Java symbols
and that might also have similarly subtle issues.


import java.io.File;
import java.io.IOException;

public class TestCase
{
   public static void main(String[] args)
      throws IOException
   {
      File fileHyphen = new File("test-file.tmp");
      File fileNbrkHyphen = new File("test\u2011file.tmp");

      createFile(fileHyphen);
      createFile(fileNbrkHyphen);
   }

   static void createFile(File file)
      throws IOException
   {
      if (!file.createNewFile())
      {
         System.out.println("Could not create " + file);
      }
   }
}


$ javac TestCase.java
$ java TestCase
$ ls test*
test-file.tmp	test‑file.tmp
$ java TestCase
Could not create test-file.tmp
Could not create test?file.tmp

(not sure what I have misconfigured that bollocksed up the Unicode on
that last line)

Cheers,
	Bent D
-- 
Bent Dalager - bcd@pvv.org - http://www.pvv.org/~bcd
                                    powered by emacs