private DbJVPackage importJarFile(
      File jarFile,
      DbJVPackage topMostPackage,
      Controller controller,
      int startJobDone,
      int endJobDone)
      throws DbException {
    DbJVClass dbClass;
    String filename = jarFile.getName();

    try {
      ZipFile zip = new ZipFile(jarFile);
      int i = 0, nb = zip.size();
      int span = endJobDone - startJobDone;

      for (Enumeration<?> e = zip.entries(); e.hasMoreElements(); ) {
        int jobDone = startJobDone + (i * span) / nb;

        ZipEntry entry = (ZipEntry) e.nextElement();
        String entryName = entry.getName();
        int idx = entryName.lastIndexOf('.');
        String ext = (idx == -1) ? null : entryName.substring(idx + 1);
        if ("class".equals(ext)) {
          InputStream is = zip.getInputStream(entry);

          ClassParser parser = new ClassParser(is, filename);
          JavaClass claz = parser.parse();
          dbClass = importClass(claz, controller);

          if (dbClass != null) {
            DbJVPackage pack = (DbJVPackage) dbClass.getCompositeOfType(DbJVPackage.metaClass);
            topMostPackage = findTopMostPackage(topMostPackage, pack);
            addToImportedPackage(pack);
          } // end if
        } // end if

        // check job done
        controller.checkPoint(jobDone);
        i++;

        // stop to reverse engineer if user has cancelled
        boolean finished = controller.isFinalState();
        if (finished) {
          break;
        }
      } // end for

      zip.close();

    } catch (IOException ex) {
      controller.println(ex.toString());
      dbClass = null;
    }

    return topMostPackage;
  } // end importClassFile()
  private DbJVClass importClassFile(String filename, Controller controller) throws DbException {
    DbJVClass dbClass;

    try {
      ClassParser parser = new ClassParser(filename);
      JavaClass claz = parser.parse();
      dbClass = importClass(claz, controller);

    } catch (IOException ex) {
      controller.println(ex.toString());
      dbClass = null;
    }

    return dbClass;
  } // end importClassFile()