code: public boolean isOn(Date date)
      {
          Calendar c = calendar;
  
          synchronized(c) {
              c.setTime(date);
  
              int dayOfYear = c.get(Calendar.DAY_OF_YEAR);
  
              c.setTime(computeInYear(c.get(Calendar.YEAR), c));
  
  //              System.out.println("  isOn: dayOfYear = " + dayOfYear);
  //              System.out.println("        holiday   = " + c.get(Calendar.DAY_OF_YEAR));
  
              return c.get(Calendar.DAY_OF_YEAR) == dayOfYear;
          }
      }
docs: Checks whether this event occurs on the given date.  This does
  <em>not</em> take time of day into account; instead it checks
  whether this event and the given date are on the same day.
  This is useful for applications such as determining whether a given
  day is a holiday.
  
  @param date  The date to check.
  @return      true if this event occurs on the given date.
  @hide draft / provisional / internal are hidden on Android