java assessment 4.2

import java.util.Scanner;

interface GetHappyNumber {
    interface FindIfHappyOrNot {
        void findSum();
        boolean checkIfHappy();
    }
}

public class Assessment_4_2 implements GetHappyNumber.FindIfHappyOrNot {
    int[] digits = new int[20];
    int sum = 0;

    void getDigits(int n) {
        int m, a, i = 1, counter = 0;
        m = n;
        while(n > 0) {
            n = n / 10;
        }
        while(m > 0) {
            a = m % 10;
            digits[counter++] = a;
            m = m / 10;
        }
    }

    public boolean checkIfHappy() {
        if (sum == 1) {
            return true;
        } else {
            return false;
        }
    }

    public void findSum() {
        int i;
        sum = 0;
        for (i = 0; i < digits.length; i++) {
            sum += (digits[i] * digits[i]);
            digits[i] = 0;
        }
    }
    public static void main(String args[]) {
        Scanner s = new Scanner(System.in);

        System.out.println("Enter a number:");

        int num = s.nextInt();

        if (num < 0) {
            System.out.println("Please enter a number greater than 1");
            System.exit(0);
        }

        int i;

        Assessment_4_2 obj = new Assessment_4_2();

        obj.getDigits(num);
        obj.findSum();

        while (!obj.checkIfHappy() && obj.sum >= 10) {
            obj.getDigits(obj.sum);
            obj.findSum();
        }

        // System.out.println("Sum: " + obj.sum);
        System.out.println("Happy? : " + obj.checkIfHappy());
    }
}