Programming Exercise 3.21 uses Zeller?s congruence to calculate the day of the week. Simplify Listing 6.12, PrintCalendar.java, using Zeller?s algorithm to get the start day of the month.

Listing

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Zeller's congruence is an algorithm developed by Christian Zeller to calculate the day of the week. The formula is 26(m + 1) 5j % 7 10 Where h is the day of the week (0: Saturday, 1: Sunday, 2: Monday, 3: Tuesday, 4: Wednesday, 5: Thursday, 6: Friday). q is the day of the month. im is the month (3: March, 4: April, . 12: December). January and February are counted as months 13 and 14 of the previous year. year j is the century (i.e., 100 k is the year of the century (i.e., year % 100). Note that the division in the formula performs an integer division. Write a program that prompts the user to enter a year, month, and day of the month, and displays the name of the day of the week. Here are some sample runs: Enter year: (e.g., 2012): 2015 |Jtter Enter month: 1-12: 1 Ferte Enter the day of the month: 1-31: 25 utte Day of the week is Sunday Enter year: (e.g., 2012): 2012 ter Enter month: 1-12: 5 -Enter Enter the day of the month: 1-31: 12 Jenter Day of the week is Saturday 1 import java.util.Scanner; 3 public class PrintCalendar { /** Main method */ public static void main(String[] args) { Scanner input = new Scanner(System.in); // Prompt the user to enter year System.out.print("Enter full year (e.g., 2012): "); int year = input.nextInt(); 10 11 // Prompt the user to enter month System.out.print("Enter month as a number between 1 and 12: "); int month = input.nextInt(); 12 13 // Print calendar for the month of the year printMonth (year, month); 16 17 18 19 /** Print the calendar for a month in a year */ public static void printMonth(int year, int month) { // Print the headings of the calendar printMonthTitle(year, month); 21 22 23 24 // Print the body of the calendar printMonthBody Cyear, month); 25 26 27 28 29 /** Print the month title, e.g., March 2012 */ public static void printMonthTitle(int year, int month) { System.out.println(" " + year); System.out.println("- System.out.printInc" Sun Mon Tue Wed Thu Fri Sat"): 30 + getMonthName(month) 31 32 33 --"); 34 35 36 37 /** Get the English name for the month */ public static String getMonthName (int month) { String monthName = switch (month) { case 1: monthName = "January"; break; case 2: monthName = "February"; break; case 3: monthName = "March"; break; case 4: monthName = case 5: monthName = "May"; break; case 6: monthName case 7: monthName 38 39 40 41 42 "April"; break; 45 46 "June"; break; "July"; break; "August"; break; 47 48 49 50 case 8: monthName case 9: monthName = "September"; break; case 10: monthName = "October"; break; case 11: monthName - "November"; break; case 12: monthName = "December"; 51 52 53 54 55 56 57 58 return monthName; /** Print month body */ 111 111 222 222 222 233 333n33 m 444 444 45