反转正整数

 1 /**
 2  * 反转正整数
 3  */
 4 import java.util.Scanner;
 5
 6 public class ReverseNumber {
 7     public static void main (String[] args) {
 8         Scanner input = new Scanner(System.in);
 9         System.out.print("输入两位以上的正整数: ");
10         int number = input.nextInt();
11         int reversedNumber = reverse(number);
12         System.out.println("The reversed number for " + number + " is " + reversedNumber);
13     }
14
15     // 取值解法
16     public static int reverse(int numberP) {
17         int reversedNumber = 0;
18         int temp = 0;
19         int digitsTester = 0;
20         // 计算出numberP是几位的正整数
21         // e.g. i = 10; i < 234; i *= 10
22         for (int i = 10; i < numberP; i *= 10) {
23             // digitsTester = 100
24             digitsTester = i;
25             // if i = 1000 > 234 , digitsTester = 1000 / 10 = 100
26             if (i > numberP) {
27                 digitsTester /= 10;
28 //                break;
29             }
30         }
31         // 求出100是10的几次方
32         int log10 = (int)Math.log10(digitsTester);
33         while (numberP != 0) {
34             for (int i = 0; i <= log10; i++) {
35                 // temp = 234 / 100 = 2
36                 temp = numberP / digitsTester;
37                 // numberP = 234 / 100 (=2) * 100 = 200
38                 numberP = numberP - numberP / digitsTester * digitsTester;
39                 // digitsTester = 100 / 10 = 10
40                 digitsTester = digitsTester / 10;
41                 // reversedNumber = 0 + 2 * 10^0
42                 reversedNumber = reversedNumber + temp * (int)Math.pow(10, i);
43             }
44         }
45         return reversedNumber;
46     }
47 }