Date & Time

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Here is an example Java class that showcases several important methods related to date and time.
import java.time.LocalDate;
import java.time.LocalTime;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;

public class DateTimeExample {

    public static void main(String[] args) {
        // Getting the current date
        LocalDate currentDate = LocalDate.now();
        System.out.println("Current Date: " + currentDate);

        // Getting the current time
        LocalTime currentTime = LocalTime.now();
        System.out.println("Current Time: " + currentTime);

        // Getting the current date and time
        LocalDateTime currentDateTime = LocalDateTime.now();
        System.out.println("Current Date and Time: " + currentDateTime);

        // Formatting date and time
        DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("dd-MM-yyyy");
        DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern("HH:mm:ss");
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss");

        String formattedDate = currentDate.format(dateFormatter);
        String formattedTime = currentTime.format(timeFormatter);
        String formattedDateTime = currentDateTime.format(dateTimeFormatter);

        System.out.println("Formatted Date: " + formattedDate);
        System.out.println("Formatted Time: " + formattedTime);
        System.out.println("Formatted Date and Time: " + formattedDateTime);

        // Parsing date and time from strings
        String dateStr = "27-06-2024";
        String timeStr = "14:30:00";
        String dateTimeStr = "27-06-2024 14:30:00";

        LocalDate parsedDate = LocalDate.parse(dateStr, dateFormatter);
        LocalTime parsedTime = LocalTime.parse(timeStr, timeFormatter);
        LocalDateTime parsedDateTime = LocalDateTime.parse(dateTimeStr, dateTimeFormatter);

        System.out.println("Parsed Date: " + parsedDate);
        System.out.println("Parsed Time: " + parsedTime);
        System.out.println("Parsed Date and Time: " + parsedDateTime);

        // Adding and subtracting dates and times
        LocalDate futureDate = currentDate.plusDays(10);
        LocalTime futureTime = currentTime.plusHours(2);
        LocalDateTime futureDateTime = currentDateTime.plusWeeks(1);

        System.out.println("Future Date (10 days from now): " + futureDate);
        System.out.println("Future Time (2 hours from now): " + futureTime);
        System.out.println("Future Date and Time (1 week from now): " + futureDateTime);

        LocalDate pastDate = currentDate.minusMonths(1);
        LocalTime pastTime = currentTime.minusMinutes(30);
        LocalDateTime pastDateTime = currentDateTime.minusYears(1);

        System.out.println("Past Date (1 month ago): " + pastDate);
        System.out.println("Past Time (30 minutes ago): " + pastTime);
        System.out.println("Past Date and Time (1 year ago): " + pastDateTime);

        // Calculating the difference between dates and times
        long daysBetween = ChronoUnit.DAYS.between(parsedDate, currentDate);
        long hoursBetween = ChronoUnit.HOURS.between(parsedTime, currentTime);
        long weeksBetween = ChronoUnit.WEEKS.between(parsedDateTime, currentDateTime);

        System.out.println("Days between parsed date and current date: " + daysBetween);
        System.out.println("Hours between parsed time and current time: " + hoursBetween);
        System.out.println("Weeks between parsed date and time and current date and time: " + weeksBetween);
    }
}

Explanation

  1. Getting the Current Date and Time:

    • LocalDate.now(): Retrieves the current date.
    • LocalTime.now(): Retrieves the current time.
    • LocalDateTime.now(): Retrieves the current date and time.

  2. Formatting Date and Time:

    • DateTimeFormatter.ofPattern("pattern"): Creates a formatter with the specified pattern.
    • format(formatter): Formats the date/time using the specified formatter.

  3. Parsing Date and Time from Strings:

    • parse(CharSequence text, DateTimeFormatter formatter): Parses a date/time from a string using the specified formatter.

  4. Adding and Subtracting Dates and Times:

    • plusDays(long days), plusHours(long hours), plusWeeks(long weeks), etc.: Adds the specified amount of time to the date/time.
    • minusMonths(long months), minusMinutes(long minutes), minusYears(long years), etc.: Subtracts the specified amount of time from the date/time.

  5. Calculating the Difference Between Dates and Times:

    • ChronoUnit.DAYS.between(start, end), ChronoUnit.HOURS.between(start, end), ChronoUnit.WEEKS.between(start, end), etc.: Calculates the difference between two dates/times in the specified units.

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