Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Handling dates and times is a common task in software development—and one that can quickly become tricky without the right tools. Fortunately, Java provides a powerful, modern date-time API through the java.time package, introduced in Java 8. This tutorial will walk you through the essentials of working with date and time in Java using this API, complete with examples you can use right away.
Why Use the java.time API?
Before Java 8, developers relied on java.util.Date, Calendar, or third-party libraries like Joda-Time. These older classes had several issues—lack of thread safety, confusing design, and mutable objects.
The java.time package:
- Is easy to use
- Is immutable and thread-safe
- Supports time zones, locales, and formatting/parsing
- Inspired by the popular Joda-Time library
1. Getting the Current Date and Time
Java offers different classes depending on what you need: only date, only time, or both.
Current Date
LocalDate today = LocalDate.now();
System.out.println("Today's Date: " + today);
Current Time
LocalTime timeNow = LocalTime.now();
System.out.println("Current Time: " + timeNow);
Current Date and Time
LocalDateTime current = LocalDateTime.now();
System.out.println("Current DateTime: " + current);
2. Working With Time Zones
When working with international applications, you’ll often need time-zone-aware dates.
Get current date-time in a specific zone:
ZonedDateTime zonedDt = ZonedDateTime.now(ZoneId.of("America/New_York"));
System.out.println(zonedDt);
List all available time zones
ZoneId.getAvailableZoneIds().forEach(System.out::println);
3. Formatting and Parsing Dates
The DateTimeFormatter class lets you convert dates to strings and vice-versa.
Formatting a date
LocalDate date = LocalDate.now();
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd-MM-yyyy");
String formatted = date.format(formatter);
System.out.println("Formatted Date: " + formatted);
Parsing a date string
String dateStr = "25-12-2025";
LocalDate parsedDate = LocalDate.parse(dateStr, formatter);
System.out.println("Parsed Date: " + parsedDate);
4. Adding and Subtracting Dates
The date-time classes include methods like plusDays(), minusMonths(), etc.
LocalDate today = LocalDate.now();
LocalDate nextWeek = today.plusWeeks(1);
LocalDate lastMonth = today.minusMonths(1);
System.out.println("Next Week: " + nextWeek);
System.out.println("Last Month: " + lastMonth);
5. Comparing Dates
You can compare dates using methods like isBefore(), isAfter(), and isEqual().
LocalDate d1 = LocalDate.of(2025, 5, 1);
LocalDate d2 = LocalDate.of(2025, 6, 1);
System.out.println(d1.isBefore(d2)); // true
System.out.println(d1.isAfter(d2)); // false
6. Calculating Differences Between Dates
Use Period for dates and Duration for times.
Difference in days, months, years
LocalDate start = LocalDate.of(2023, 1, 1);
LocalDate end = LocalDate.of(2025, 1, 1);
Period period = Period.between(start, end);
System.out.println(period.getYears() + " years, " +
period.getMonths() + " months, " +
period.getDays() + " days");
Difference in hours, minutes, seconds
LocalTime t1 = LocalTime.of(10, 0);
LocalTime t2 = LocalTime.of(15, 30);
Duration duration = Duration.between(t1, t2);
System.out.println("Hours: " + duration.toHours());
System.out.println("Minutes: " + duration.toMinutes());
7. Converting Between Old and New Date APIs
If you are integrating with older codebases, you may need conversions.
From Date to Instant
Date oldDate = new Date();
Instant instant = oldDate.toInstant();
From Instant to LocalDateTime
LocalDateTime dt = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
From LocalDateTime to Date
Date backToDate = Date.from(dt.atZone(ZoneId.systemDefault()).toInstant());
8. Working With Periods and Durations
Period (Date-based)
Used for years, months, and days.
Period period = Period.of(0, 2, 10); // 2 months and 10 days
Duration (Time-based)
Used for hours, minutes, and seconds.
Duration duration = Duration.ofHours(5);
Conclusion
The Java java.time API offers a clean, modern, and powerful way to handle date and time in your applications. Whether you’re formatting dates, calculating time differences, or working with time zones, the API provides tools that are both intuitive and robust.
If you’re still using legacy date classes, now is the perfect time to adopt the newer API for safer, cleaner, and more maintainable code.
