Introduction

In this demo I have used NetBeans IDE 8.2 for debugging purpose. But you can use any java programming language compiler as per your availability..

import java.util.Scanner;
public class Javaexcercise { 
 public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter an integer: ");
        long n = input.nextLong();
        System.out.println("The sum of the digits is: " + sumDigits(n));
 
    }
 
    public static int sumDigits(long num) {
        int sum = 0;
        while (num != 0) {
            sum += num % 10;
            num /= 10;
        }
        return sum;
    }
}

Result