public static String getAbsolutePath(File f)
{
    if (f == null)
        return null;
    String a = File.pathSeparator;
    String b = File.separator;
    String c = f.getAbsolutePath();
    StringTokenizer tok = new StringTokenizer(f.getAbsolutePath(),
            File.separator);
    ArrayList segments = new ArrayList();
    while (tok.hasMoreTokens())
    {
        String s = tok.nextToken();
        if (s.equals("..")) 
            segments.remove(segments.size() - 1); // remove last

        else
            segments.add(s);
    }

    StringBuffer buf = new StringBuffer();
    for (Iterator i = segments.iterator(); i.hasNext();)
    {
        String seg = (String) i.next();
        // don't start off with \ on windows. C: is right, not \C:

        if ((buf.length() == 0) && File.separator.equals("\\"))

            buf.append (seg);

        else
            buf.append(File.separator).append(seg);
    }
    return buf.toString();
}