1 package test_4_2;
 2 
 3 public class CountsOfUnevenNum {
 4 
 5     public static void main(String[] args) {
 6 
 7         /** 求0，1，2，3，4，5，6，7所能组成的8位奇数个数。 */
 8         
 9         int[] numArray = {0, 1, 2, 3, 4, 5, 6, 7};
10         
11         int unevenNum = countUneven(numArray);
12         int zero = countZero(numArray);
13         int midNum = numArray.length - zero - 1;
14         
15         int countMid = getCounts(midNum);
16         int count = (numArray.length - zero) * countMid * unevenNum; 
17         
18         System.out.println("可组成" + count + "个奇数");
19         
20     }
21 
22     /** 阶乘 */
23     private static int getCounts(int numCount) {
24         
25         int count = 1;
26         
27         for (int i = 1; i <= numCount; i++) {
28             count *= i;
29         }
30         
31         return count;
32         
33     }
34 
35     /** 0的个数 */
36     private static int countZero(int[] numArray) {
37         
38         int count = 0;
39         
40         for (int i = 0; i < numArray.length; i++) {
41             if (numArray[i] == 0) {
42                 count++;
43             }
44             
45         }
46         
47         return count;
48     }
49 
50     /** 奇数个数 */
51     private static int countUneven(int[] numArray) {
52         
53         int count = 0;
54         
55         for (int i = 0; i < numArray.length; i++) {
56             if (numArray[i] % 2 == 1) {
57                 count++;
58             }
59         }
60         
61         return count;
62     }
63 
64 }

 

结果如下：

可组成2880个奇数