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 ParseException12     {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

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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126         System.out.println(c1.get(Calendar.MONTH));27         c1.add(Calendar.MONTH,-1);//月份减128         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

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Sun Jun 01 10:56:52 CST 2014

5

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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 ParseException14     {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：