Date and Time

The LocalTime Class

The LocalTime class is similar to the other classes whose names are prefixed with Local, but deals in time only. This class is useful for representing human-based time of day, such as movie times, or the opening and closing times of the local library. It could also be used to create a digital clock, as shown in the following example:

LocalTime thisSec;
 
for (;;) {
    thisSec = LocalTime.now();
 
    // implementation of display code is left to the reader
    display(thisSec.getHour(), thisSec.getMinute(), thisSec.getSecond());
}

The LocalTime class does not store time zone or daylight saving time information.

 

The LocalDateTime Class

The class that handles both date and time, without a time zone, is LocalDateTime, one of the core classes of the Date-Time API. This class is used to represent date (month-day-year) together with time (hour-minute-second-nanosecond) and is, in effect, a combination of LocalDate with LocalTime. This class can be used to represent a specific event, such as the first race for the Louis Vuitton Cup Finals in the America’s Cup Challenger Series, which began at 1:10 p.m. on August 17, 2013. Note that this means 1:10 p.m. in local time. To include a time zone, you must use a ZonedDateTime or an OffsetDateTime, as discussed in Time Zone and Offset Classes.

In addition to the now() method that every temporal-based class provides, the LocalDateTime class has various of() methods (or methods prefixed with of) that create an instance of LocalDateTime. There is a from() method that converts an instance from another temporal format to a LocalDateTime instance. There are also methods for adding or subtracting hours, minutes, days, weeks, and months. The following example shows a few of these methods:

System.out.printf("now: %s%n", LocalDateTime.now());
 
System.out.printf("Apr 15, 1994 @ 11:30am: %s%n",
                  LocalDateTime.of(1994, Month.APRIL, 15, 11, 30));
 
System.out.printf("now (from Instant): %s%n",
                  LocalDateTime.ofInstant(Instant.now(), ZoneId.systemDefault()));
 
System.out.printf("6 months from now: %s%n",
                  LocalDateTime.now().plusMonths(6));
 
System.out.printf("6 months ago: %s%n",
                  LocalDateTime.now().minusMonths(6));

This code produces output that will look similar to the following:

now: 2013-07-24T17:13:59.985
Apr 15, 1994 @ 11:30am: 1994-04-15T11:30
now (from Instant): 2013-07-24T17:14:00.479
6 months from now: 2014-01-24T17:14:00.480
6 months ago: 2013-01-24T17:14:00.481