/** This class contains a java implementation of the doomsday algorithm */

public class Doomsday {

/** Tests the implementation */

public static void test(){

System.out.printf("Oct 13 1994 should be a Thursday: %s\n", getWeekDay(1994, 10, 13));

System.out.printf("July 2 1364 should be a Monday: %s\n", getWeekDay(1364, 7, 2));

System.out.printf("February 7 2020 should be a Friday: %s\n", getWeekDay(2020, 2, 7));

}

/** Gets the weekday of a specific date */

public static String getWeekDay(int year, int month, int day){

int[] months = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};

year -= month < 3 ? 1 : 0;

int weekday = (year + year / 4 - year / 100 + year / 400 +

months[month - 1] + day) % 7;

switch(weekday){

case 0:

return "Sunday";

case 1:

return "Monday";

case 2:

return "Tuesday";

case 3:

return "Wednesday";

case 4:

return "Thursday";

case 5:

return "Friday";

case 6:

return "Saturday";

}

return "Unknown";

}

}