Java8 Overview of the java.time package

Category : Java | Sub Category : Java8 Features | By Prasad Bonam Last updated: 2023-11-13 05:45:24 Viewed : 234

The java.time package, introduced in Java 8, provides a comprehensive set of classes for handling date and time in a more modern and sophisticated way than the previous java.util.Date and java.util.Calendar classes. The new API in java.time is part of the Java Date and Time API (JSR-310) and is inspired by the popular Joda-Time library. The primary classes in the java.time package are in the java.time subpackage.

Here is an overview of some key classes and concepts in the java.time package:

1. LocalDate:

• Represents a date without a time component.
• Useful for dealing with birthdays, anniversaries, etc.

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LocalDate today = LocalDate.now();

2. LocalTime:

• Represents a time without a date component.
• Useful for representing times of day, such as business opening hours.

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LocalTime now = LocalTime.now();

3. LocalDateTime:

• Combines LocalDate and LocalTime to represent both date and time.
• Represents a point in time without a time zone.

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LocalDateTime dateTime = LocalDateTime.now();

4. ZonedDateTime:

• Extends LocalDateTime to include time zone information.
• Useful for representing instants in time in a specific time zone.

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ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of("America/New_York"));

5. Duration:

• Represents a duration of time, such as "2 hours" or "30 seconds."

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Duration duration = Duration.ofHours(2);

6. Period:

• Represents a period of time in terms of years, months, and days.

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Period period = Period.ofMonths(3);

7. Instant:

• Represents an instantaneous point in time.
• Useful for converting between different time representations.

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Instant instant = Instant.now();

8. ZoneId:

• Represents a time zone.
• Used to convert between ZonedDateTime and Instant.

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ZoneId zoneId = ZoneId.of("America/Los_Angeles");
ZonedDateTime losAngelesTime = ZonedDateTime.now(zoneId);9. DateTimeFormatter:

• Formats and parses dates and times.
• Allows customization of the output format.

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LocalDateTime dateTime = LocalDateTime.now();
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String formattedDateTime = dateTime.format(formatter);

10. TemporalAdjusters:

• Provides common date adjustments, such as finding the first or last day of the month.

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LocalDate firstDayOfMonth = LocalDate.now().with(TemporalAdjusters.firstDayOfMonth());

11. ChronoUnit:

• Represents units of time, such as days or hours.
• Used with Duration to perform time-based arithmetic.

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LocalDateTime now = LocalDateTime.now();
LocalDateTime future = now.plus(3, ChronoUnit.DAYS);

12. Clock:

• Represents the current instant in time.
• Useful for obtaining the current date and time in a specific time zone.

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Clock clock = Clock.systemDefaultZone();
LocalDateTime now = LocalDateTime.now(clock);

Example:

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import java.time.*;

public class DateTimeExample {

    public static void main(String[] args) {
        // LocalDate
        LocalDate today = LocalDate.now();
        System.out.println("Todays date: " + today);

        // LocalTime
        LocalTime now = LocalTime.now();
        System.out.println("Current time: " + now);

        // LocalDateTime
        LocalDateTime dateTime = LocalDateTime.now();
        System.out.println("Date and time: " + dateTime);

        // ZonedDateTime
        ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of("America/New_York"));
        System.out.println("New York time: " + zonedDateTime);

        // Duration
        Duration duration = Duration.ofHours(2);
        System.out.println("Duration: " + duration);

        // Period
        Period period = Period.ofMonths(3);
        System.out.println("Period: " + period);

        // Instant
        Instant instant = Instant.now();
        System.out.println("Instant: " + instant);

        // ZoneId
        ZoneId zoneId = ZoneId.of("Europe/Paris");
        ZonedDateTime parisTime = ZonedDateTime.now(zoneId);
        System.out.println("Paris time: " + parisTime);

        // DateTimeFormatter
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        String formattedDateTime = dateTime.format(formatter);
        System.out.println("Formatted date and time: " + formattedDateTime);

        // TemporalAdjusters
        LocalDate firstDayOfMonth = LocalDate.now().with(TemporalAdjusters.firstDayOfMonth());
        System.out.println("First day of the month: " + firstDayOfMonth);

        // ChronoUnit
        LocalDateTime future = dateTime.plus(