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=Integer.toString(num);        int total=0;        for(int i=0; i