Java.util (date and calendar)

public class date implements Java.io.Serializable, cloneable, comparable<date>{public Date () {//Current time     This (System.currenttimemillis ());        The public date (long date) {//assigns the Date object and initializes the object to represent the specified number of milliseconds since the standard base time, known as the epoch, or January 1, 1970 00:00:00 GMT.    Fasttime = date;    } @Deprecated public Date (int, int, month, int date) {This (year, month, Date, 0, 0, 0); } @Deprecated public Date (int, int month, int date, int hrs, int min) {This (year, month, Date, hrs, min, 0)    ;        } ... public String toString () {//"EEE MMM dd HH:mm:ss zzz yyyy";...... "."        Basecalendar.date Date = normalize ();        StringBuilder sb = new StringBuilder (28);        int index = Date.getdayofweek (); if (index = = gcal.        SUNDAY) {index = 8;                        } converttoabbr (SB, Wtb[index]). Append (");  EEE converttoabbr (SB, Wtb[date.getmonth ()-1 + 2 + 7]). Append (");       MMM CALENDARUTILS.SPRINTF0D (SB, Date.getdayofmonth (), 2). Append (");   DD calendarutils.sprintf0d (SB, Date.gethours (), 2). Append (': '); HH calendarutils.sprintf0d (SB, Date.getminutes (), 2). Append (': '); MM calendarutils.sprintf0d (SB, Date.getseconds (), 2). Append (");        SS TimeZone Zi = Date.getzone (); if (Zi! = null) {Sb.append (Zi.getdisplayname (Date.isdaylighttime (), Zi. Short, locale.us));        ZZZ} else {sb.append ("GMT");  } sb.append ("). Append (Date.getyear ());    yyyy return sb.tostring (); }}

The Date represents the number of milliseconds 00:00:00 from 1970-01-01, and the value is independent of the time zone. Most of the date methods are obsolete and are replaced by the method of the Calendar class

public class Datetest {@SuppressWarnings ("deprecation") public static void main (string[] args) {Date d = new Date (); System.out.println (d); System.out.println (System.currenttimemillis ()); Long L = Date.parse ("Sun Sep 03:16:48 CST 2017"); System.out.println (L);D ate data = new Date (l); SYSTEM.OUT.PRINTLN (data);D ate day1=new Date (11,3,4); System.out.println (Day1);}} Output: Sun Sep 03:17:22 CST 201715049846420471505035008000Sun Sep 17:16:48 CST 2017Tue Apr 00:00:00 CST 1911

Calendar

Public abstract class Calendar implements Serializable, Cloneable, comparable<calendar> {protected calendar ()        {This (Timezone.getdefaultref (), Locale.getdefault (Locale.Category.FORMAT));    Sharedzone = true;        } protected Calendar (TimeZone zone, Locale alocale) {fields = new Int[field_count];        IsSet = new Boolean[field_count];        Stamp = new Int[field_count];        This.zone = Zone;    Setweekcountdata (Alocale); } public static Calendar getinstance () {Calendar cal = Createcalendar (Timezone.getdefaultref (), L        Ocale.getdefault (Locale.Category.FORMAT));        Cal.sharedzone = true;    Return cal; } public static Calendar getinstance (TimeZone zone) {return Createcalendar (Zone, Locale.getdefault (Lo Cale.    Category.format));    Public final Date GetTime () {return new date (Gettimeinmillis ()); The public final void settime (date date) {Settimeinmillis (date.gettime());        } public Long Gettimeinmillis () {if (!istimeset) {updatetime ();    } return time; }........

The Calendar class is an abstract class, and the static method of the Calendar class getinstance () can initialize a Calendar object: calendar now = Calendar.getinstance ();

You can use the following three methods to set the calendar to any one time:

  Set (int year, int month,int date)  

If you want to get the year, month, hour and other information you can use:  

Now.get (calendar.month); This method 0 means January, 1 means February  

  Get (Calendar.day_of_month) get the day of the month

  Get (Calendar.day_of_year) get the day of the year  

  Gettimemillis () Gets the millisecond representation of the current time

Conversion of calendar and date
(1) Calendar converted to date
Calendar cal=calendar.getinstance ();
Date Date=cal.gettime ();
(2) Date converted to Calendar
Date Date=new date ();
Calendar cal=calendar.getinstance ();
Cal.settime (date);

Formatted output date Time:

　　　　Date data = new Date ();
The SimpleDateFormat class is used to parse and format the date string output
SimpleDateFormat f2=new SimpleDateFormat ("YYYY year mm month DD Day hh mm min ss seconds");
SimpleDateFormat f3=new SimpleDateFormat ("Yy/mm/dd hh:mm");
SimpleDateFormat f4=new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss");//equivalent to now.tolocalestring ()
SimpleDateFormat f5=new SimpleDateFormat ("yyyy years mm DD Day hh mm min ss sec E");
System.out.println (F2.format (d));
System.out.println (F3.format (d));
System.out.println (F4.format (d));
System.out.println (F5.format (d));

About the implementation class for the calendar: GregorianCalendar

JavaOnly carry the Gregorian calendar (Gregorian, solar) implementation, that is the java.util.GregorianCalendar class

　　Calendar calendar = newGregorianCalendar();

　　Calendar类有着对应的get方法，让你获取到年、月、日、小时、分钟、秒、毫秒和给定日期的时区

　　CalendarClass has a corresponding set method, so you can also set these fields

Java.util (date and calendar)