Duration and Period

Learn spans with Duration and Period.

Duration vs Period

Duration and Period both represent a length of time, but with different units. Duration is hour-minute-second based; Period is year-month-day based.

Example: Duration.between(start, end) gives the length between two times in hours and minutes. Period.between(birth, today) gives the age between two dates in years, months and days. Using the wrong type produces odd results; that is why you pick Period for dates and Duration for times.

Date ranges with Period

Period expresses year-month-day based ranges. It can be created with methods like Period.ofYears(1) or Period.ofMonths(6); you can also take the difference between two dates with Period.between.

Example: LocalDate next = today.plus(Period.ofYears(1)). This adds one year to today. Passing a Period to plus gives the same result as calling plusYears(1); but it is more flexible when you want to carry the range as a variable.

Exercise Find the duration between two times

Create two times: LocalTime.of(10, 0) and LocalTime.of(12, 30). Print the minutes between them using Duration.between(start, end).toMinutes() with System.out.println.

Show example solution

import java.time.Duration;
import java.time.LocalTime;

public class DurationExample {
    public static void main(String[] args) {
        LocalTime start = LocalTime.of(10, 0);
        LocalTime end = LocalTime.of(12, 30);
        System.out.println(Duration.between(start, end).toMinutes());
    }
}

Test yourself

Which class holds an hour-minute based length of time?
- Duration
- Period
- LocalDate
- Instant
Show answer

Duration — Duration is hour-minute-second based.

Complete the Duration.between call

Duration d = Duration.____(start, end);

Show answer

Duration d = Duration.between(start, end);

Match the Duration and Period methods

Duration

Hour based
Period

Day based
between

Between two times
ofDays

Make with days

Next lesson: DateTimeFormatter

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