6.2 Period and Duration Explained

The Java Date and Time API introduced in Java 8 provides two classes, Period and Duration, to handle different types of time intervals. Understanding these classes is crucial for managing date and time differences in your Java SE 11 applications.

Key Concepts

1. Period

Period represents a date-based amount of time in the ISO-8601 calendar system, such as "2 years, 3 months, and 4 days". It is used to measure the difference between two dates or to represent a specific period of time.

Example

        import java.time.LocalDate;
        import java.time.Period;
        
        public class PeriodExample {
            public static void main(String[] args) {
                LocalDate startDate = LocalDate.of(2020, 1, 1);
                LocalDate endDate = LocalDate.of(2023, 4, 5);
                
                Period period = Period.between(startDate, endDate);
                System.out.println("Period: " + period.getYears() + " years, " + period.getMonths() + " months, " + period.getDays() + " days");
                
                Period customPeriod = Period.of(2, 3, 4);
                System.out.println("Custom Period: " + customPeriod.getYears() + " years, " + customPeriod.getMonths() + " months, " + customPeriod.getDays() + " days");
            }
        }
    

2. Duration

Duration represents a time-based amount of time, such as "34.5 seconds". It is used to measure the difference between two times or to represent a specific duration of time.

Example

        import java.time.Duration;
        import java.time.LocalTime;
        
        public class DurationExample {
            public static void main(String[] args) {
                LocalTime startTime = LocalTime.of(10, 0);
                LocalTime endTime = LocalTime.of(10, 30);
                
                Duration duration = Duration.between(startTime, endTime);
                System.out.println("Duration: " + duration.getSeconds() + " seconds");
                
                Duration customDuration = Duration.ofMinutes(15);
                System.out.println("Custom Duration: " + customDuration.getSeconds() + " seconds");
            }
        }
    

Examples and Analogies

Think of Period as a timeline that measures date intervals, such as the time between two birthdays. For example, if you want to know how many years, months, and days have passed between two dates, Period is the right tool.

On the other hand, Duration is like a stopwatch that measures time intervals, such as the time between two events in a day. For example, if you want to know how many seconds have passed between two specific times, Duration is the right tool.

By mastering Period and Duration, you can handle date and time differences with precision and flexibility, making your Java SE 11 applications more robust and reliable.