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java开始到熟悉66-69

2024-07-02 14:33:42   224人阅读

                          本次内容：DateFormat类

1、DateFormat类

 1 package array;
 2 /**
 3  * 时间和字符串之间的转化
 4  */
 5 import java.text.DateFormat;
 6 import java.text.ParseException;
 7 import java.text.SimpleDateFormat;
 8 import java.util.Date;
 9 
10 public class dateformat {
11     public static void main(String[] args) throws ParseException
12     {
13         DateFormat d=new SimpleDateFormat("yyyy-MM-dd");
14         Date t=new Date(123);
15         String str=d.format(t);//将时间对象按照格式化字符串，转换成字符串
16         System.out.println(str);
17         System.out.println("###################");
18         String str1="1977,7,7";
19         DateFormat d1=new SimpleDateFormat("yyyy,MM,dd");//此处字符串格式必须和前面的字符串格式一致，或前面的字符串按此格式定义
20         Date t1=d1.parse(str1);//将相应格式的字符串转换成时间
21         System.out.println(t1);
22     }
23 }

运行结果：
1970-01-01
###################
Thu Jul 07 00:00:00 CST 1977

2、Calendar类

 1 package array;
 2 /**
 3  * 此时日历类及日期计算
 4  */
 5 import java.util.Calendar;
 6 import java.util.Date;
 7 import java.util.GregorianCalendar;
 8 
 9 public class gregorian {
10     public static void main(String[] args)
11     {
12         Calendar c=new GregorianCalendar();
13         c.set(2001,1,1,12,12,12);
14         Date d=c.getTime();
15         System.out.println(d);
16         System.out.println(c.getTime());
17         System.out.println("###################");
18         Calendar c1=new GregorianCalendar();
19         c1.set(Calendar.YEAR, 2014);
20         c1.set(Calendar.MONTH,5);
21         c1.set(Calendar.DAY_OF_MONTH,1);
22         System.out.println(c1.getTime());
23         System.out.println(c1.get(Calendar.MONTH));
24         System.out.println("###################");
25         c1.add(Calendar.MONTH,1);//月份加1
26         System.out.println(c1.get(Calendar.MONTH));
27         c1.add(Calendar.MONTH,-1);//月份减1
28         System.out.println(c1.get(Calendar.MONTH));
29     }
30 }

运行结果：
Thu Feb 01 12:12:12 CST 2001
Thu Feb 01 12:12:12 CST 2001
###################
Sun Jun 01 10:56:52 CST 2014
5
###################
6
5

3、一个可视化日历练习：

 1 package array;
 2 
 3 import java.text.DateFormat;
 4 import java.text.ParseException;
 5 import java.text.SimpleDateFormat;
 6 import java.util.Calendar;
 7 import java.util.Date;
 8 import java.util.GregorianCalendar;
 9 import java.util.Scanner;
10 
11 
12 public class visualcalendar {
13     public static void main(String[] args) throws ParseException
14     {
15         System.out.println("请输入日期（格式为某年-某月-某日）：");
16         Scanner input=new Scanner(System.in);
17         String str=input.nextLine();
18         DateFormat df=new SimpleDateFormat("yyyy-MM-dd");
19         Date d=df.parse(str); 
20         Calendar c=new GregorianCalendar();
21         c.setTime(d);
22         int currentday=c.get(Calendar.DATE);
23         c.set(Calendar.DATE, 1);
24         System.out.println(c.get(Calendar.DAY_OF_WEEK));
25         System.out.println(c.getActualMaximum(Calendar.DATE));
26         System.out.println("日\t一\t二\t三\t四\t五\t六");
27         int day=c.get(Calendar.DAY_OF_WEEK);
28         int max=c.getActualMaximum(Calendar.DATE);
29         int i,j;
30         for(j=0;j<(day-1);j++)
31         {
32             System.out.print("\t");
33         }
34         for(i=1;i<=max;i++)
35         {
36             System.out.print(i);
37             if(i==currentday)
38             {
39                 System.out.print("*");
40             }
41             System.out.print(‘\t‘);
42             int grade=c.get(Calendar.DAY_OF_WEEK);
43             if(grade==Calendar.SATURDAY)
44                 System.out.println();
45             c.add(Calendar.DATE, 1);
46         }
47     }
48 }

运行结果：

 


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