Java: Compute the sum of the digits of an integer

Java Basic: Exercise-33 with Solution

Write a Java program and compute the sum of an integer's digits.

Test Data:
Input an intger: 25

Pictorial Presentation:

Sample Solution:

Java Code:

import java.util.Scanner;

public class Exercise33 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        
        // Prompt the user to input an integer
        System.out.print("Input an integer: ");
        
        // Read the integer from the user
        long n = input.nextLong();
        
        // Calculate and display the sum of the digits
        System.out.println("The sum of the digits is: " + sumDigits(n));
    }

    public static int sumDigits(long n) {
        int sum = 0;
        
        // Calculate the sum of the digits
        while (n != 0) {
            sum += n % 10;
            n /= 10;
        }
        
        return sum;
    }
}

Explanation:

In the exercise above -

• It uses the Scanner class to obtain input from the user.
• First, it prompts the user to input an integer using System.out.print("Input an integer: ") and reads the input into the variable 'n'.
• It then calls a separate method named "sumDigits()" and passes the input integer n as an argument.
• Inside the "sumDigits()" method:
• It initializes an integer variable 'sum' to store the sum of the digits, starting with 0.
• It enters a while loop that continues as long as 'n' is not equal to 0.
• Inside the loop, it calculates the last digit of 'n' using the modulus operator (n % 10) and adds it to the 'sum' variable.
• It then removes the last digit from 'n' by dividing it by 10 (n /= 10).
• This process continues until all digits of the original number have been processed.
• Finally, it returns the 'sum' containing the sum of the digits.
• Finally, back in the "main()" method, it prints the result of the "sumDigits()" method, displaying the sum of the digits of the entered integer.

Sample Output:

Input an intger: 25                                                                                           
The sum of the digits is: 7 

Flowchart:

Java Code Editor:

Previous: Write a Java program to compare two numbers.
Next: Write a Java program to compute the area of a hexagon.