Question

Write a Java Program using the following instruction:

Create the following 3 methods that calculate and display the sum or product of the integers from 1 to the number input.

getNum Receives no input. Prompts the user to enter a number, use a loop to validate. Returns the result.

calcSum Receives an integer as input. Calculates the sum of the integers from 1 to this number. Returns the result.

calcProd Receives an integer as input. Calculates the product of the integers from 1 to this number. Returns the result.

Main should: Prompt for a character that determines if you want to calculate the sum (‘S’ or ‘s’) or product (‘P’ or ‘p’). You should use a switch to process the choices. Upper and lower case values should work the same way. Use default to give an error message if anything else is entered. (You can input as String or char)

if a valid option is entered, use getNum to prompt for the number

Note that calcSum and calcProduct RETURN the result to main, and the output is printed in main. For example, if you input 5 as the number, and ‘S’, the program should calculate 1 + 2 + 3 + 4 + 5 and display the sum as 15. If you input 5 and ‘P’ the program should calculate 1 x 2 x 3 x 4 x 5 and display the product as 120. . The process should repeat as long as the user wants to continue. This loop should be in main. DO NOT use System.exit command to end the program. . See sample output below.

Enter S for sum, P for prod:z

Invalid choice Again(y/n)? y

Enter S for sum, P for prod:s

Enter an integer greater than 1: 1

Must be greater than 1, re-enter: -3

Must be greater than 1, re-enter: 3

The sum of the numbers from 1 to 3 is 6 Again(y/n)? y

Enter S for sum, P for prod:p

Enter an integer greater than 1: 4

The product of the numbers from 1 to 4 is 24 Again(y/n)? n

Answer 1

Answer

import java.util.*;
import java.util.Scanner;
class MyCode
{
   public static void main (String[] args) throws java.lang.Exception
   {
       int num;
       String ch,choice;
       Scanner in=new Scanner(System.in);
       do
       {
           System.out.println("Enter S for sum, P for prod : ");
           ch=in.next();
           switch(ch.charAt(0))
           {
               case 'S':
               case 's':
               num=getNum();
               System.out.println("The sum of the numbers from 1 to "+num+" is : "+calcSum(num));
               break;
               case 'P':
               case 'p':
               num=getNum();
               System.out.println("The product of the numbers from 1 to "+num+" is : "+calcProd(num));
               break;
               default:
                   System.out.println("Invalid choice! Try Again..");                      
           }
           System.out.println("Try Again (Y/N) : ");
           choice=in.next();
       }while(choice.charAt(0)!='N'&&choice.charAt(0)!='n');
   }
   public static int getNum()
   {
       Scanner in=new Scanner(System.in);
       int n;
       do
       {
           System.out.println("Enter an integer greater than 1 : ");
           n=in.nextInt();
           if(n<=1)
               System.out.println("Must be greater than 1, re-enter..");
           else
               break;  
       }while(n<=1);
       return n;
   }
   public static int calcSum(int num)
   {
       int sum=0;
       for(int i=1;i<=num;i++)
           sum+=i;
       return sum;
   }
   public static int calcProd(int num)
   {
       int product=1;
       for(int i=1;i<=num;i++)
           product=product*i;
       return product;
   }
}

OUTPUT