Thread: Need explanation of the code

Hello ! I need help as to what the code below does for each of its statement, when dd/mm/yyyy format is enter, it should give 20 Dec 2010 is a Monday:

public static String dayOfWeek(int dd, int mm, int yyyy) {
			int[] monthIndices = {1,4,4,0,2,5,0,3,6,1,4,6};
			String[] dayOfWeek = {"Saturday", "Sunday", "Monday", 
			                      "Tuesday", "Wednesday", "Thursday", 
			                      "Friday"};
			if ((yyyy % 4 == 0) && !(yyyy % 100 == 0) || 
			    (yyyy % 400 == 0)){
				monthIndices[0] = 0;
				monthIndices[1] = 3;
			}
			int yy = yyyy % 100;
			int yyDiv4 = yy / 4;
			int keyNumber = monthIndices[mm-1];
			int sum = yy+yyDiv4+keyNumber+dd;
			int adjValue = 0;
			if (yyyy / 100 == 18)
				adjValue = 2;
			else 
				if (yyyy / 100 == 20)
					adjValue = 6;
				else
					if (yyyy / 100 == 21)
					adjValue = 4;
			int remainder = (sum + adjValue) % 7;
			String day = dayOfWeek[remainder];
			return day;
			}
		}

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db

@db: even if you've a good knowledge of java, you need some experience to figure out that the following statement

if ((yyyy % 4 == 0) && !(yyyy % 100 == 0) || 
			    (yyyy % 400 == 0))

is used to calculate if a year is a leap year.

thanks for reply

have doubts as to why we need to do the code as to:

if year modules 400 is 0
then is_leap_year
else if year modules 100 is 0
then not_leap_year
else if year modules 4 is 0
then is_leap_year