Swing/CalendarFieldStepSize のバックアップ(No.3)

HashMap<Integer, Integer> stepSizeMap = new HashMap<>();
stepSizeMap.put(Calendar.HOUR_OF_DAY, 1);
stepSizeMap.put(Calendar.MINUTE,      1);
stepSizeMap.put(Calendar.SECOND,      30);
stepSizeMap.put(Calendar.MILLISECOND, 500);
JSpinner spinner2 = new JSpinner(new SpinnerDateModel(d, null, null, Calendar.SECOND) {
  @Override public Object getPreviousValue() {
    Calendar cal = Calendar.getInstance();
    cal.setTime(getDate());
    Integer calendarField = getCalendarField();
    Integer stepSize = Optional.ofNullable(stepSizeMap.get(calendarField)).orElse(1);
    cal.add(calendarField, -stepSize);
    Date prev = cal.getTime();
    return prev;
  }
  @Override public Object getNextValue() {
    Calendar cal = Calendar.getInstance();
    cal.setTime(getDate());
    Integer calendarField = getCalendarField();
    Integer stepSize = Optional.ofNullable(stepSizeMap.get(calendarField)).orElse(1);
    cal.add(calendarField, stepSize);
    Date next = cal.getTime();
    return next;
  }
});