Question

public class LeapYear { 
    public static void main(String[] args) { 
        int year = Integer.parseInt(args[0]);
        boolean isLeapYear;

        // divisible by 4
        isLeapYear = (year % 4 == 0);

        // divisible by 4 and not 100
        isLeapYear = isLeapYear && (year % 100 != 0);

        // divisible by 4 and not 100 unless divisible by 400
        isLeapYear = isLeapYear || (year % 400 == 0);

        System.out.println(isLeapYear);
    }
}

I am passing 1900 as my input. The first condition evaluates to true as its divisible by 4, but again 1900 should be divisible by 100 too…

How come i am getting 1900 as not a leap year…. what is the value being passed in the second && condition… (year % 100 !=0)

Update

public class TestSample {
    public static void main(String[] args){

        int leapYear = Integer.parseInt(args[0]);
        boolean isLeapYear;

        isLeapYear = (leapYear % 4 == 0) && (leapYear % 100 != 0);

        System.out.println("Its Leap Year" +isLeapYear);

    }

}

Compiling this program prints 1900 not a leapYear How???? Here i am not even checking for the whether its divisible by 400 or not.

Answer 1

To explain your code:

isLeapYear = (year % 4 == 0);
// isLeapYear = true

isLeapYear = isLeapYear && (year % 100 != 0);
// year % 100 IS 0. so the second part evaluates to false giving
// true && false which yields isLeapYear as false

isLeapYear = isLeapYear || (year % 400 == 0);
// this is just false || false
// which evaluates to false

Another suggestion I have for you is to just use the GregorianCalendar to find what you want:

GregorianCalendar cal = new GregorianCalendar();
System.out.println( cal.isLeapYear(1900) );