public static void main(String[] args) throws Exception {
    TimeZone.setDefault(TimeZone.getTimeZone("Europe/London"));
    DateFormat format_z = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.S z");
    DateFormat format_Z = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.S Z");
    for (int year = 1800 ; year < 2010 ; ++year) {
      Date june_20_at_12_34_56_pm = new GregorianCalendar(year,
                                                          Calendar.JUNE,
                                                          20,
                                                          12,
                                                          34,
                                                          56).getTime();
      if (format_z.parse(format_z.format(june_20_at_12_34_56_pm)).getTime() != june_20_at_12_34_56_pm.getTime()) {
        System.out.println("z " + year);
      }
      if (format_Z.parse(format_Z.format(june_20_at_12_34_56_pm)).getTime() != june_20_at_12_34_56_pm.getTime()) {
        System.out.println("Z " + year);
      }
    }
  }