I want to get Year, Month, Day, etc from Java Date to compare with Gregorian Calendar date in Java. Is this possible?

java

date-comparison

java-time-api

best-practices

byNikita Barsukov·Jan 9, 2025

Say you're in a hurry. Here's the quickest snippet to make that Date -> Calendar transition, extract the year, month and day, and then side-by-side this with another GregorianCalendar.

Calendar cal = new GregorianCalendar();
cal.setTime(new Date()); // Convert Date. A.K.A "Battery included!" 

int year = cal.get(Calendar.YEAR); // Eureka! Got the year.
int month = cal.get(Calendar.MONTH); // The month, Jan = 0 (So December isn't 12! 😉)
int day = cal.get(Calendar.DAY_OF_MONTH); // Here comes the sun (Day).

// Assuming anotherCal is a GregorianCalendar.
// Did we just became best friends? Check if they match.
boolean sameYear = year == anotherCal.get(Calendar.YEAR);
boolean sameMonth = month == anotherCal.get(Calendar.MONTH);
boolean sameDay = day == anotherCal.get(Calendar.DAY_OF_MONTH);

Key Points: The get() of Calendar finds the YEAR, MONTH, DAY_OF_MONTH for you. Remember, months are sure playing a prank starting at 0.

Embrace the `java.time.LocalDate` for efficient solutions

When it became clear that some Date methods belong with the dinosaurs, java.time.LocalDate became the knight in shining armor from Java 8 onwards.

LocalDate localDate = new Date().toInstant()
    .atZone(ZoneId.systemDefault())
    .toLocalDate(); // "Date, meet LocalDate. You guys will handle comparisons well."

LocalDate anotherDate = LocalDate.of(2021, Month.JANUARY, 25); 

boolean isSameDay = localDate.isEqual(anotherDate); // The big question: "Are we equals?"

Handle time zones with care. They are notorious for messing up with the best-laid plans.

Understand the need of using localized methods when time means everything.

Difference? `java.time.Period` shows the way

Has the 'How many days apart?' question ever kept you awake? java.time.Period comes to the rescue. Your hands needn't get dirty with manual calculations.

Period period = Period.between(anotherDate, localDate); // The middle-man of date difference.
System.out.printf("Difference is %d years, %d months, and %d days", 
    period.getYears(), period.getMonths(), period.getDays());

Just another reason why java.time is way cool. It keeps date operations intuitive and trouble-free more than ever.

A calendar year isn't just a year!

Using SimpleDateFormat, remember to choose your year symbols carefully. yyyy is for calendar year and YYYY is for week year.

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); // No Y2K bug here.
String dateString = sdf.format(new Date()); // Viola! Your date string plays the symphony.

Don't let ISO week date system standards surprise you with unexpected results.

Future-proof code, no metal rust here!

Take note fellow time-travelers! When coding for future you want it to last and adapt to changes in the Java platform. Wave your wands and magic java.time.* classes turn to gold, replacing the straw of java.util.Date and java.util.Calendar.

Migrate: Replace Date with LocalDate.
Avoid: Use Calendar.get() or LocalDate.
Precise: Be explicit with ZoneId.
Efficient: Period and Duration lessen manual hiccups.