• 題目：判斷一個素數(shù)能被幾個9整除

 1     public class _045Equals9Model {
 2 
 3     public static void main(String[] args) {
 4         equals9Model();
 5     }
 6 
 7     private static void equals9Model() {
 8         int number = input();
 9         int num = sushu(number);
10         judge(num);
11     }
12 
13     private static void judge(int number) {
14         // 定義一個count用于統(tǒng)計輸入的素數(shù)能被9整除的個數(shù)
15         int s = 0, count = 0, temp = number;
16         if (number != 0) {
17             for (int i = 1; i < 100; i++) {
18                 s = temp % 9;
19                 if (s == 0) {
20                     temp = temp / 9;
21                     count++;
22                 } else {
23                     System.out.println(number + "不能被9整除");
24                     break;
25 
26                 }
27             }
28             System.out.println(number + "能夠被 " + count + "個9整除");
29 
30         }
31     }
32 
33     private static int sushu(int number) {
34         boolean b = true;
35         for (int j = 2; j < number; j++) {
36             if (number % j == 0) {
37                 b = false;
38             }
39         }
40         if (b) {
41             System.out.println(number + "是素數(shù)");
42             return number;
43         } else {
44             System.out.println("您輸入的數(shù)不是素數(shù)，請重新輸入");
45             // 如果輸入的不是素數(shù) 那么調(diào)用input方法 重新輸入一個素數(shù)
46             int number1 = input();
47             // 這里是方法的遞歸調(diào)用 即調(diào)用方法自己本身 去判斷重新輸入的數(shù)是不是素數(shù)
48             int number2 = sushu(number1);
49             return number2;
50         }
51     }
52 
53     private static int input() {
54         System.out.println("請輸入一個數(shù)");
55         Scanner sc = new Scanner(System.in);
56         int number = sc.nextInt();
57         return number;
58     }
59 
60 }