258. Add Digits

Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.

For example:

Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has only one digit, return it.

public class Solution {    public int addDigits(int num) {                 String numStr = String.valueOf(num);                String[] numArray = new String[numStr.length()];                int[] numInt = new int[numStr.length()];                int result = 0;                for(int i=0;i<numStr.length();i++){                        numArray[i] = numStr.substring(i, i+1);                        numInt[i] = Integer.parseInt(numArray[i]);                        result = result + numInt[i];                    }                while(result>=10){                return addDigits(result);                }                return result;       }}