### Question:
Day extends RegularTimePeriod implements Serializable { @Override public int hashCode() { return this.serialDate.hashCode(); } Day();  Day(int day, int month, int year);  Day(SerialDate serialDate);  Day(Date time);  Day(Date time, TimeZone zone, Locale locale); SerialDate getSerialDate(); int getYear(); int getMonth(); int getDayOfMonth(); @Override long getFirstMillisecond(); @Override long getLastMillisecond(); @Override void peg(Calendar calendar); @Override RegularTimePeriod previous(); @Override RegularTimePeriod next(); @Override long getSerialIndex(); @Override long getFirstMillisecond(Calendar calendar); @Override long getLastMillisecond(Calendar calendar); @Override boolean equals(Object obj); @Override int hashCode(); @Override int compareTo(TimePeriod o1); @Override String toString(); static Day parseDay(String s);  }### Answer:
@Test public void testHashcode() { Day d1 = new Day(1, 2, 2003); Day d2 = new Day(1, 2, 2003); assertEquals(d1, d2); int h1 = d1.hashCode(); int h2 = d2.hashCode(); assertEquals(h1, h2); }