简单的日历制作

 1 import java.util.*;
 2 import java.text.*;
 3 class Demo 
 4 {
 5     public static void main(String[] args) 
 6     {
 7         long weekday = 0;
 8         int c = 0;
 9         Scanner scan = new Scanner(System.in);
10         String str = "1900-1-1";//1900-1-1是星期一
11         System.out.println("请输入年月(年-月):");
12         String str1 = scan.next();
13         String str2 = str1 + "-1";//为了和1900-1-1到输入的时间计算出差多少天而加上字符"-1"
14         String str3 = null;
15         long yearDays = charge(str,str2);//计算出1900-1-1到输入的时间相差的天数
16         weekday = yearDays%7+1;//计算出一号一星期几
17         System.out.println(weekday);
18         String str4 = str1.substring(5);//截取字符，截取到后面的月份
19         int num = 0;
20         num=Integer.valueOf(str4); 
21         String str5 = str1.substring(0,4);
22         
23         int num1 = 0;
24         num1 = Integer.valueOf(str5);//把截取到的字符月份转换为整形
25         switch (num)
26         {
27         case 1:
28         case 3:
29         case 5:
30         case 7:
31         case 8:
32         case 10:
33         case 12:
34             c = 31;
35             break;
36         case 4:
37         case 6:
38         case 9:
39         case 11:
40             c = 30;
41             break;
42         case 2:
43             {
44                 //判断是否为闰年
45                 if ((num1%4 == 0 && num1%100 != 0) || num1 % 400 ==0)
46                 {
47                     c = 29;
48                 }else {
49                     c = 28;
50                 }
51             }
52             break;
53         }
54         System.out.println("星期日	"+"星期一	"+"星期二	"+"星期三	"+"星期四	"+"星期五	"+"星期六	");
55           if(weekday%7!=0){//判断星期天是不是一号，是就不打印*号
56              for (int i = 1; i <= weekday ; i++)//打印*号
57             {
58 
59                 System.out.print("  *"+"	");
60             
61             }
62         }
63         int day=0;
64         for (int i = (int)weekday  ; i < c+ (int)weekday ; i++ )//打印每天的号数
65         {
66             day++;//每天号数记录
67             if ((i) % 7 == 0)
68             {
69                 System.out.println();
70             }
71             System.out.print("  "+day+"	");
72         }
73     }
74 
75     public static long charge(String date1,String date2){
76         
77         //做时间差
78         //将String转为Date做计算
79         SimpleDateFormat sd = new SimpleDateFormat("yyyy-MM-dd");
80         long charge = 0;
81         try{
82             Date d1 = sd.parse(date1);  
83             Date d2 = sd.parse(date2);
84             //时间也是以毫秒为单位。
85             charge = (d2.getTime() - d1.getTime()) / (1000*24*60*60);
86         }catch(ParseException e){
87             System.out.println(e);
88         }
89         return charge;
90     }
91 }