Problems unzipping files

Question

Hello there,
I tried to create two small programs: Zip and UnZip, using the java.util.zip package. The Zip file works perfectly and WinAce can read the files zipped. But the UnZip program doesn't seem to work: it unzips
the files almost correctly. I unzipped a text file and it's readable, but except for the normal characters that appeared in the original text, some other not-displayable characters appear at certain points (quite many since the unzipped files are a few kilob bigger that the original not-zipped file). I really don't understand what the problem is. Well, actually, I didn't read any tutorial about using java.util.zip, I just read the API documentation and I sorted out a way of zipping and unzipping. Please, if you can, tell me what is the problem with the program:
public class UnZip
     public static void main(String[] arg)
          try
               if (arg.length < 1)
                    System.out.println("Usage: java UnZip <zip file> [to dir]");
                    System.exit(0);
               String dir = "";
               if (arg.length > 1)
                    dir = arg[1] + System.getProperty("file.separator");
                    File f = new File(arg[1]);
                    if (!f.exists()) f.mkdirs();
               System.out.println("Decompressing files from file " + arg[0]);
               ZipFile read = null;
               try
                    read = new ZipFile(arg[0]);
               catch (ZipException ex)
                    System.err.println("Zip error when reading file " + arg[0]);
                    System.exit(1);
               catch (IOException ex)
                    System.err.println("I/O Exception when reading file " + arg[0]);
                    System.exit(1);
               Enumeration en = read.entries();
               while (en.hasMoreElements())
                    ZipEntry entry = (ZipEntry) en.nextElement();
                    System.out.println("\tDecompressing file " + entry.getName());
                    FileOutputStream out;
                    try
                         out = new FileOutputStream(dir + entry.getName());
                    catch (FileNotFoundException ex)
                         System.err.println("\tCannot write down to file " + dir + entry.getName());
                         continue;
                    InputStream re = read.getInputStream(entry);
                    int av = 0;
                    while ((av = re.available()) != 0)
                         byte[] b = new byte[av < 64 ? av : 64];
                         re.read(b);
                         out.write(b);
                    out.close();
                    System.out.println("\tDone decompressing file " + entry.getName());
               read.close();
               System.out.println("Done decompressing files");
          catch (Exception e)
               new File(arg[1]).delete();
               e.printStackTrace(System.err);
}

Answer 1

It is the following code which has a swapped conditional expression,
and also I would loop differently.
          int av = 0;
          while ((av = re.available()) != 0)
               byte[] b = new byte[av < 64 ? av : 64];
               re.read(b);
               out.write(b);
          }Move the byte buffer outside, and better think in kilobytes.
Read is waiting and forcing an actual read, so it seems
safer than an available.
byte[] buffer = new byte[1024];
for (;;) {
    int nread = re.read(buffer);
    if (nread < 0)
        break;
    out.write(buffer, 0, nread);