Period and Duration

The Java Date-Time API represents time intervals using two distinct types: Period (date-based: years, months, days) and Duration (time-based: seconds, nanoseconds).

Period vs. Duration

• Period: Focuses on date concepts (e.g. 2 years, 3 months, 12 days). Used with LocalDate.
• Duration: Focuses on precise machine time (e.g. 48 hours, 30 minutes). Used with LocalTime or Instant.

Code Walkthrough

This program demonstrates calculating intervals using both Period and Duration.

import java.time.LocalDate;
import java.time.Instant;
import java.time.Period;
import java.time.Duration;
public class IntervalDemo {
    public static void main(String[] args) throws InterruptedException {
        // 1. Period calculation
        LocalDate bday = LocalDate.of(1995, 10, 25);
        LocalDate now = LocalDate.now();
        Period age = Period.between(bday, now);
        System.out.println("Age: " + age.getYears() + " years");
// 2. Duration calculation
        Instant start = Instant.now();
        Thread.sleep(500); // Simulate execution delay
        Instant end = Instant.now();
        Duration elapsed = Duration.between(start, end);
        System.out.println("Elapsed: " + elapsed.toMillis() + " ms");
    }
}

Interview-Relevant Information