code: public File getAbsolutePath(String filename)
    {
      if (pathenv == null || pathSep == null  || fileSep == null)
        {
          return null;
        }
      int     val = -1;
      String    classvalue = pathenv + pathSep;
  
      while (((val = classvalue.indexOf(pathSep)) >= 0) &&
             classvalue.length() > 0) {
        //
        // Extract each entry from the pathenv
        //
        String entry = classvalue.substring(0, val).trim();
        File f = new File(entry);
  
        try {
          if (f.isDirectory()) {
            //
            // this entry in the pathenv is a directory.
            // see if the required file is in this directory
            //
            f = new File(entry + fileSep + filename);
          }
          //
          // see if the filename matches and  we can read it
          //
          if (f.isFile() && f.canRead()) {
            return f;
          }
        } catch (Exception exp){ }
        classvalue = classvalue.substring(val+1).trim();
      }
      return null;
    }
docs: Returns the full path name of this file if it is listed in the
  path