Local Time

There’s a special class to represent the time of day in Java. The LocalTime class represents daytime in hours-minutes-seconds format, such as 06:30 or 11:45:30. It doesn’t store information about the date or a time zone. Time is stored with nanosecond precision (for example, 13:45:30.123456789). The LocalTime class could be used to store things like an opening and closing time of a shop or a train schedule.

This class belongs to the java.time package and pretty much resembles the LocalDate class.

Creating LocalTime, current time and constants

First of all, let’s see how do we create an instance of the LocalTime class. An instance that stores the current time can be created as shown below:

LocalTime now = LocalTime.now();

If we want to pass a specific time to an instance, we should employ either of the two static methods of and parse to create an instance of LocalTime :

LocalTime.of(11, 45);        // 11:45
LocalTime.of(11, 45, 30);    // 11:45:30
LocalTime.parse("11:45:30"); // 11:45:30 (hours, minutes, seconds)

In the first line, second and nanosecond fields will be set to zero.

The hour of a day is an int number from 0 to 23, while minutes and seconds are numbers from 0 to 59. Nanoseconds can be any integer numbers from 0 to 999,999,999. The following code throws an exception:

LocalTime.of(24, 1, 1); // it throws DateTimeException (24 is an invalid value for hours)

It’s also possible to create an instance of LocalTime by using static methods ofSecondOfDay and ofNanoOfDay. In this case, we should indicate seconds and nanoseconds of a day respectively:

LocalTime time = LocalTime.ofSecondOfDay(12345); // 03:25:45
LocalTime nanotime = LocalTime.ofNanoOfDay(1234567890); // 00:00:01.234567890

There are some predefined constants in the LocalTime class as well :

LocalTime.MIN; // 00:00
LocalTime.MAX; // 23:59:59.999999999
LocalTime.NOON; // 12:00
LocalTime.MIDNIGHT; // 00:00

Remember that it is a good practice to use constants whenever it is possible!

LocalTime: hours, minutes and seconds

Now let’s discuss a bunch of useful methods of the LocalTime class.

Let’s suppose we have an instance of LocalTime :

LocalTime time = LocalTime.of(11, 45, 30); // 11:45:30

By using the following methods we can get hours, minutes, seconds and nanoseconds of it:

time.getHour();   // 11
time.getMinute(); // 45
time.getSecond(); // 30
time.getNano();   // 0, nanoseconds

Another useful method is toSecondOfDay. It returns the time in seconds of the day from the given LocalTime instance. For our example, it’ll be:

time.toSecondOfDay(); // 42330

Arithmetic methods of LocalTime

The class also has methods to add and subtract hours, minutes, seconds and nanoseconds:

LocalTime time1 = time.plusHours(5); // 16:45:30
LocalTime time2 = time.plusHours(22); // 09:45:30
LocalTime time3 = time.minusMinutes(10); // 11:35:30
LocalTime time4 = time.minusSeconds(30); // 11:45

The following methods return a copy of an instance with one altered part of the time:

LocalTime time1 = time.withHour(23); // 23:45:30
LocalTime time2 = time.withMinute(50); // 11:50:30
LocalTime time3 = time.withSecond(0); // 11:45

Keep in mind, that LocalTime class is immutable and all considered methods return a new instance.

As you can see, the LocalTime class provides enough methods that will simplify your job and save your time when you’ll have to deal with hours, minutes and seconds.