WAP to find sum of digits using recursion in BlueJ, Java

QUESTION:
Write a program to find the sum of digits of a number using recursion.

CODE:
import java.io.*;
class recursion_sum_of_digits
  { //Start of class
    public int sum_of_digits(int num) 
     { 
      int rem=0;
      if(num==0)
       { //When number is 0, sum of digits is 0
       return(0);
       }
      else 
       {
      rem=num%10; //Extracting 1st digit of number
      return(rem+sum_of_digits(num/10));
       }
     }
     public static void main()throws IOException
    { //Start of main() function
      BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
      recursion_sum_of_digits obj=new recursion_sum_of_digits();
      System.out.println("Enter the number : ");
      int number=Integer.parseInt(in.readLine());
      int sum=obj.sum_of_digits(number);
      System.out.println("The sum of digits in "+number+" is : "+sum+"\n");
    } //End of main() function
  } //End of class