14 输入某年某月某日，判断这一天是这一年的第几天

题目：

输入某年某月某日，判断这一天是这一年的第几天？ 1. 程序分析：以 3 月 5 日为例，应该先把前两个月的加起来， 然后再加上 5
天即本年的第几天， 特殊情况，闰年且输入月份大于 3 时需考虑多加一天。

 1     public class _014JudgmentDate {
 2 
 3     public static void main(String[] args) {
 4         while (true) {
 5             days();
 6         }
 7     }
 8 
 9     private static void days() {
10         int year, month, day;
11         int days = 0;
12         int feb = 28;
13 
14         Scanner scanner = new Scanner(System.in);
15         System.out.println("请输入年份:");
16         year = scanner.nextInt();
17         System.out.println("请输入月份:");
18         month = scanner.nextInt();
19         System.out.println("请输入天数");
20         day = scanner.nextInt();
21 
22         if (year < 0 || month < 0 || month > 12 || day < 0 || day > 31) {
23             System.out.println("请重新输入");
24         } else {
25 
26             for (int i = 1; i < month; i++) {
27                 switch (month) {
28                 case 1:
29                     days = day;
30                     break;
31                 case 2:
32                     if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
33                         feb = 29;
34                     } else {
35                         feb = 28;
36                     }
37                     days = 31 + day;
38                     break;
39                 case 3:
40                     days = 31 + feb + day;
41                     break;
42                 case 4:
43                     days = 31 + feb + 31 + day;
44                     break;
45                 case 5:
46                     days = 31 + feb + 31 + 30 + day;
47                     break;
48                 case 6:
49                     days = 31 + feb + 31 + 30 + 31 + day;
50                     break;
51                 case 7:
52                     days = 31 + feb + 31 + 30 + 31 + 30 + day;
53                     break;
54                 case 8:
55                     days = 31 + feb + 31 + 30 + 31 + 30 + 31 + day;
56                     break;
57                 case 9:
58                     days = 31 + feb + 31 + 30 + 31 + 30 + 31 + 31 + day;
59                     break;
60                 case 10:
61                     days = 31 + feb + 31 + 30 + 31 + 30 + 31 + 31 + 30 + day;
62                     break;
63                 case 11:
64                     days = 31 + feb + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31
65                             + day;
66                     break;
67                 case 12:
68                     days = 31 + feb + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31
69                             + 30 + day;
70                 }
71                 System.out.println(year + " 年 " + month + " 月 " + day
72                         + "号是今年的第" + days + "天");
73             }
74         }
75     }
76 
77 }