why making a new variable result a different value here?

rosababy :

I have two sets of code. if I make a new variable inside the loop, the code works as it's suppose to.

public static int subsequentLeapYear(int year) {
    for(int i =1; i < 9; i++) {
        int nextYear = year + i;
        if(isLeapYear(nextYear)) {
            return nextYear;
        }
    }
    return 0;
}

public static int subsequentYear(int year) {
    for(int i = 1; i < 9; i++) {
        year += i;
        if(isLeapYear(year)) {
            return year;
        }
    }
    return 0;
}

}

    System.out.println(subsequentYear(8));
    System.out.println(subsequentLeapYear(8));

it's suppose to print 12. for the first one it prints 36 not 12. I can't figure out why it's printint 36.

Edit:

public static boolean isLeapYear(int year) {
        if(year % 400 == 0) {
            return true;
        }
        if(year % 100 != 0 && year % 4 == 0) {
            return true;
        }
        return false;
    }

Gabriele Mariotti :

It happens because:

int nextYear = year + i;

year is always the same value.

ex:

i=1 -> nextYear = 8 +1 = 9;
i=2 -> nextYear = 8 +2 = 10;

While:

year += i;

year is not always the same value.

i=1 -> year = 8 +1 = 9;
i=2 -> year = 9 +2 = 11;