Java (Find the future date with if else statements)

Question

I have a question that I can\'t figure it out , Thank you: Write a program that prompts the user to enter an integer for today\'s day of the week (Sunday is 0 ,Monday is 1 ,

Answer 1

The question is from a book titled "Introduction to Java programming" by Y. Daniel Liang. Apart from using the string type, which I believe is covered in the next chapter; the solution I wrote for this exercise uses only what you have been taught so far.

import java.util.Scanner;

public class Exercise_03_06 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        System.out.print("Enter today's day: ");
        int todaysDay = input.nextInt();

        System.out.print("Enter the number of days elapsed since today: ");
        int elapsedDays = input.nextInt();

        int futureDay = (todaysDay + elapsedDays) % 7;
        String day_of_week = "";

        switch (todaysDay) {
            case 0: day_of_week = "Sunday"; break;
            case 1: day_of_week = "Monday"; break;
            case 2: day_of_week = "Tuesday"; break;
            case 3: day_of_week = "Wednesday"; break;
            case 4: day_of_week = "Thursday"; break;
            case 5: day_of_week = "Friday"; break;
            case 6: day_of_week = "Saturday";
        }

        switch (futureDay) {
            case 0:
                System.out.println("Today is " + day_of_week + " and the future day is Sunday."); break;
            case 1:
                System.out.println("Today is " + day_of_week + " and the future day is Monday."); break;
            case 2:
                System.out.println("Today is " + day_of_week + " and the future day is Tuesday."); break;
            case 3:
                System.out.println("Today is " + day_of_week + " and the future day is Wednesday."); break;
            case 4:
                System.out.println("Today is " + day_of_week + " and the future day is Thursday."); break;
            case 5:
                System.out.println("Today is " + day_of_week + " and the future day is Friday."); break;
            case 6:
                System.out.println("Today is " + day_of_week + " and the future day is Saturday.");
        }
    }
}

Output:

Enter today's day: 0
Enter the number of days elapsed since today: 31
Today is Sunday and the future day is Wednesday.

Notes:

• The first switch statement assigns a day of type string to the variable day_of_week which is later used for printing "today's day".

• To obtain the future day, you must find the remainder of the sum of today's day and the number of days elapsed divided by 7.

• The last switch statement "matches" a case number that is identical to the number stored within the futureDay variable (which is obtained by performing the mathematical operation noted above).