Leetcode【202】Happy Number（Java版）

class Solution {
    public boolean isHappy(int n) {
        String s = String.valueOf(n);
        while (true) {
            int sum = 0;
            for(int i = 0;i < s.length(); i++){      		
                char ch = s.charAt(i);
                int  intNum = ch - '0';
                sum += intNum * intNum; 
            } 
            s = String.valueOf(sum);
            if (Integer.valueOf(s) == 1)
                return true;
            if (Integer.valueOf(s) == 4)
                return false;    
        }
    }
}