### Question:
TimestampDatum extends Datum { @Override public int compareTo(Datum datum) { if (datum.kind() == TajoDataTypes.Type.TIMESTAMP) { TimestampDatum another = (TimestampDatum) datum; return Longs.compare(timestamp, another.timestamp); } else if (datum.isNull()) { return -1; } else { throw new InvalidOperationException(datum.type()); } } TimestampDatum(long timestamp); long getTimestamp(); int getEpoch(); long getJavaTimestamp(); int getCenturyOfEra(); int getYear(); int getMonthOfYear(); int getDayOfYear(); int getDayOfWeek(); int getWeekOfYear(); int getDayOfMonth(); int getHourOfDay(); int getMinuteOfHour(); int getSecondOfMinute(); int getMillisOfSecond(); int getUnixTime(); String toString(); static String asChars(TimeMeta tm, TimeZone timeZone, boolean includeTimeZone); String toString(TimeZone timeZone, boolean includeTimeZone); @Override long asInt8(); @Override String asChars(); @Override int size(); @Override byte [] asByteArray(); @Override byte[] asTextBytes(); @Override Datum equalsTo(Datum datum); @Override int compareTo(Datum datum); @Override boolean equals(Object obj); @Override Datum plus(Datum datum); @Override Datum minus(Datum datum); @Override int hashCode(); @Override TimeMeta asTimeMeta(); static final int SIZE; }### Answer:
@Test public void testCompareTo() { TimestampDatum theday = DatumFactory.createTimestamp("2014-11-12 15:00:00.68"); TimestampDatum thedaybefore = DatumFactory.createTimestamp("2014-11-11 15:00:00.56"); assertThat(theday.compareTo(thedaybefore) > 0, is(true)); assertThat(thedaybefore.compareTo(theday) > 0, is(false)); }