Java – How to calculate leap year

By mkyong | Updated: October 14, 2013

Viewed: 30,088

Tags: leap year

A leap year is a year containing one additional day (366 days a year). Review the leap year algorithm :

if year is divisible by 400 then
   is_leap_year
else if year is divisible by 100 then
   not_leap_year
else if year is divisible by 4 then
   is_leap_year
else
   not_leap_year

P.S Algorithm from wikipedia leap year.

1. Java Leap Year Example

Java example to determine if the given year is a leap year.

package com.mkyong.utils;

public class DateTimeExample {

    public static void main(String[] args) {

	DateTimeExample obj = new DateTimeExample();
	System.out.println("1993 is a leap year : " + obj.isLeapYear(1993));
	System.out.println("1996 is a leap year : " + obj.isLeapYear(1996));
	System.out.println("2012 is a leap year : " + obj.isLeapYear(2012));

    }

    public boolean isLeapYear(int year) {

	if ((year % 400 == 0) || ((year % 4 == 0) && (year % 100 != 0))) {
		return true;
	} else {
		return false;
	}
    }
	
}

Output

1993 is a leap year : false
1996 is a leap year : true
2012 is a leap year : true

2. GregorianCalendar Example

Alternatively, you can use GregorianCalendar.isLeapYear() API.

    import java.util.GregorianCalendar;
	
    //...
    public boolean isLeapYear(int year) {

	GregorianCalendar cal = (
		GregorianCalendar) GregorianCalendar.getInstance();

	return cal.isLeapYear(year);
    }

References

1. Wikipedia : Leap Year
2. Wikipedia : Gregorian calendar
3. GregorianCalendar Java doc