AddDigitsTotal - 把数字中单个数相加

 1 public class AddDigitsTotal {
 2     public static int addOnce(int n) {
 3         int result = 0;
 4         while (n != 0) {
 5             result += n%10;
 6             n = n/10;
 7         }
 8         return result;
 9     }
10 
11     public static int addDigits(int num) {
12         int res = 0;
13         res = addOnce(num);
14         while (res > 9) {
15             res = addOnce(res);
16         }
17         return res;
18     }
19     public static void main(String args[]){
20         for (int i = 900; i < 919; i++) {
21             System.out.print((i) + "\t");
22         }
23         System.out.println();
24         for (int i = 900; i < 919; i++) {
25             System.out.print(addDigits(i) + "\t");
26         }
27         for (int i = 0; i < 10000; i++) {
28             if (addDigits(i) >= 10) {
29                 System.out.print("ERROR");
30             }         
31         }
32     }
33 }