DateTime { public void setTime(int hour, int minute, int second) { dateTime = LocalDateTime.of(dateTime.toLocalDate(), LocalTime.of(hour, minute, second)); } DateTime();  DateTime(int year, int month, int day, int hour, int minute, int second); String getDateTime(); String getDate(); String getTime(); void setDateTime(int year, int month, int day, int hour, int minute, int second); void setDate(int year, int month, int day); void setTime(int hour, int minute, int second); long getTimeInMillisec(); long getTimeInMillisec(int year, int month, int day, int hour, int minute, int second); @Override String toString();  }
@Test public void setTime() throws Exception { dateTime.setTime(21, 30, 0); System.out.println(dateTime.getDateTime()); }