How to add a long integer to existing program

The code works. But, 开发者_高级运维I need to include long integers. How can I do that? I've tried a million things. I'm not good at this either so it takes me 5 times longer to get a simple code. Please help.

import java.util.Scanner;
public class Exercise2_6M
{
    public static void main(String[] args)
    {
        // Create a Scanner
        Scanner input = new Scanner(System.in);
        // Enter amount
        System.out.print("Enter an integer:");
        int integer = input.nextInt();
        // Calculations
        int rinteger = Math. abs (integer);
        int sum = 0;
        int i=0;
        while(rinteger / Math.pow(10,i) > 0)
        {
            sum+=getDigit(rinteger,i);
            i++;
        }
        // Display results
        System.out.println("Sum all digits in " + integer + " is " + sum);
    }
    public static int getDigit(int num, int power)
    {
        return (num % (int)Math.pow(10,power+1)) / (int)Math.pow(10,power);
    }
}

Read the input value as a string and then use the BigInteger class to perform calculations with very large values​​.

A recursive solution can be much leaner:

import java.util.Scanner;
public class Exercise2_6M
 {
    public static void main (String [] args)
    {
        Scanner input = new Scanner (System.in);
        System.out.print ("Enter an long:");
        long lng = input.nextLong ();
        int sum = getDigitSum (lng);
        System.out.println ("Sum all digits in " + lng + " is " + sum);
    }

    public static int getDigitSum (long num)
    {
        if (num < 10L) return (int) num;
        else return ((int)(num % 10)) + getDigitSum (num/10L);
    }
}