What is a Leap Year?
Leap year is a year, occurring once every four years, that has 366 days including February 29 as an intercalary day.
- Is the year divisible by 4? If no – it’s not a leap year
- If yes – Is the year divisible by 100? If no – it’s a leap year
- If yes – Is the year divisible by 400? If no – it’s not a leap year
- If yes – it’s a leap year
- If yes – Is the year divisible by 400? If no – it’s not a leap year
- If yes – Is the year divisible by 100? If no – it’s a leap year
In this tutorial we will implement this logic and find out year is a Leap year or not?
Let’s get started:
Create class CrunchifyFindLeapYear.java. Just copy and paste below code.
Here there are two different ways we will check if year is a leap year or not?
package crunchify.com.java.tutorials;
import java.util.GregorianCalendar;
/**
* @author crunchify.com
* Program: In Java how to find if Year is Leap Year or not?
* Two different methods.
*/
public class CrunchifyFindLeapYear {
public static void main(String[] args) {
CrunchifyFindLeapYear crunchifyInstance = new CrunchifyFindLeapYear();
crunchifyLog("Is it a leap year?: " + crunchifyInstance.isLeapYear(createRandomIntBetween(1900, 2021)));
crunchifyLog("Is it a leap year?: " + crunchifyInstance.isLeapYear(createRandomIntBetween(1900, 2021)));
crunchifyLog("Is it a leap year?: " + crunchifyInstance.isLeapYear(createRandomIntBetween(1900, 2021)));
crunchifyLog("Is it a leap year?: " + crunchifyInstance.isLeapYear(createRandomIntBetween(1900, 2021)));
crunchifyLog("Is it a leap year?: " + crunchifyInstance.isLeapYearUsingGregorianCalendar(createRandomIntBetween(1900, 2021)));
crunchifyLog("Is it a leap year?: " + crunchifyInstance.isLeapYearUsingGregorianCalendar(createRandomIntBetween(1900, 2021)));
crunchifyLog("Is it a leap year?: " + crunchifyInstance.isLeapYearUsingGregorianCalendar(createRandomIntBetween(1900, 2021)));
crunchifyLog("Is it a leap year?: " + crunchifyInstance.isLeapYearUsingGregorianCalendar(createRandomIntBetween(1900, 2021)));
}
// Simple Crunchify Print Utility
private static void crunchifyLog(String s) {
System.out.println(s);
}
// Generate Random Year between 1900 and 2021
public static int createRandomIntBetween(int start, int end) {
int year = start + (int) Math.round(Math.random() * (end - start));
crunchifyLog("\n==> " + year + "");
return year;
}
// Method-1: Logic to find out if Year is a Leap year or not?
public boolean isLeapYear(int year) {
return (year % 400 == 0) || ((year % 4 == 0) && (year % 100 != 0));
}
// Method-2: Logic to find out if Year is a Leap year or not using GregorianCalendar.
public boolean isLeapYearUsingGregorianCalendar(int year) {
// GregorianCalendar is a concrete subclass of Calendar and provides the standard calendar system used by most of the world.
// GregorianCalendar is a hybrid calendar that supports both the Julian and Gregorian calendar systems with the support of a single discontinuity,
// which corresponds by default to the Gregorian date when the Gregorian calendar was instituted (October 15, 1582 in some countries, later in others).
// The cutover date may be changed by the caller by calling setGregorianChange().
GregorianCalendar crunchifyDates = (
GregorianCalendar) GregorianCalendar.getInstance();
// isLeapYear(): Determines if the given year is a leap year. Returns true if the given year is a leap year.
// To specify BC year numbers, 1 - year number must be given. For example, year BC 4 is specified as -3.
return crunchifyDates.isLeapYear(year);
}
}
IntelliJ IDEA Result:
Just run above program as Java Application and you will see result as below.
==> 2015 Is it a leap year : false ==> 1936 Is it a leap year : true ==> 1992 Is it a leap year : true ==> 1960 Is it a leap year : true ==> 1949 Is it a leap year : false ==> 1969 Is it a leap year : false ==> 1924 Is it a leap year : true ==> 1926 Is it a leap year : false Process finished with exit code 0
Let me know if you face any issue running above program.