static int daysInMonth() {
  long now = now();
  ret daysInMonth(localYear(now), localMonth(now));
}

static int daysInMonth(int year, int month) {
  java.util.Calendar calendar = java.util.Calendar.getInstance();
  calendar.set(java.util.Calendar.YEAR, year);
  calendar.set(java.util.Calendar.MONTH, month);
  ret calendar.getActualMaximum(java.util.Calendar.DATE);
}