210 calender
Calender类概述
file:///C:/Users/13833123813/Desktop/jdk-17_doc-all/docs/api/java.base/java/util/Calendar.html
Module java.base
Package java.util
class Calendar
java.lang.Object
java.util.Calendar
| 1 |
All Implemented Interfaces: Serializable, Cloneable, Comparable<Calendar> Direct Known Subclasses:
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GregorianCalendar public abstract class Calendar extends Object implements Serializable, Cloneable, Comparable<Calendar> |
所有实现的接口： 可序列化、可克隆、可比较<日历> 直接已知子类： GregorianCalendar public abstract class Calendar 扩展对象 实现可序列化、可克隆、可比较的<Calendar> |
| 2 |
The Calendar class is an abstract class that provides methods for converting between a specific instant in time and a set of calendar fields字段 such as YEAR, MONTH, DAY_OF_MONTH, HOUR, and so on, and for manipulating the calendar fields, such as getting the date of the next week. An instant瞬间 in time can be represented代表 by a millisecond value that is an offset抵消 from the Epoch, January 1, 1970 00:00:00.000 GMT (Gregorian). |
Calendar类是一个抽象类，它提供了一些方法，用于在特定的时间瞬间和一组日历字段（如年、月、月中日、小时等）之间进行转换，并用于操作日历字段（如获取下周的日期）。 时间上的一个瞬间可以用毫秒值表示，毫秒值是从1970年1月1日00:00:00.000 GMT（格里高利）开始的历元偏移量。 |
| 3 |
The class also provides additional fields and methods for implementing a concrete calendar system outside the package. Those fields and methods are defined as protected. |
该类还提供了用于在包外部实现具体日历系统的附加字段和方法。 这些字段和方法被定义为受保护。 |
| 4 |
Like other locale-sensitive敏感 classes, Calendar provides a class method, getInstance, for getting a generally useful常用的 object of this type. Calendar's getInstance method returns a Calendar object whose calendar fields have been initialized with the current date and time: Calendar rightNow = Calendar.getInstance(); |
与其他对区域设置敏感的类一样，Calendar提供了一个类方法getInstance，用于获取这种类型的常用对象。 Calendar的getInstance方法返回一个日历对象，该对象的日历字段已使用当前日期和时间初始化： Calendar rightNow=Calendar.getInstance（）； |
| 5 |
A Calendar object can produce all the calendar field values needed to implement the date-time formatting for a particular language and calendar style (for example, Japanese-Gregorian, Japanese-Traditional). Calendar defines the range of values returned by certain calendar fields, as well as their meaning. For example, the first month of the calendar system has value MONTH == JANUARY for all calendars. Other values are defined by the concrete subclass, such as ERA. See individual field documentation and subclass documentation for details. |
Calendar对象可以生成实现特定语言和日历样式（例如，日文公历、日文繁体）的日期时间格式所需的所有日历字段值。 Calendar定义某些日历字段返回的值的范围及其含义。 例如，对于所有日历，日历系统的第一个月的值month==一月。其他值由具体的子类定义，例如ERA。 有关详细信息，请参阅单个字段文档和子类文档。 |
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（module）myCalender
（package）it01e210
（class）CalenderDemo
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package it01e210;
import java.util.Calendar;
//Calendar类是一个抽象类，它提供了一些方法，
// 用于在特定的时间瞬间和一组日历字段（如年、月、月中日、小时等）之间进行转换，并用于操作日历字段（如获取下周的日期）。
//Calendar提供了一个类方法getInstance，用于获取这种类型的常用对象。
//Calender rightNow = Calender.getInstance();
public class CalenderDemo {
public static void main(String[] args) {
//get object by getInstance-method
//write Ca and then choose one from the following choices, so you import the package easily.
Calendar c = Calendar.getInstance();//ctrl b"getInstance" and we know that this method implements by polymorphism
System.out.println(c);
//OUTPUT:java.util.GregorianCalendar[time=1632323465797,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Shanghai",offset=28800000,dstSavings=0,useDaylight=false,transitions=31,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2021,MONTH=8,WEEK_OF_YEAR=39,WEEK_OF_MONTH=4,DAY_OF_MONTH=22,DAY_OF_YEAR=265,DAY_OF_WEEK=4,DAY_OF_WEEK_IN_MONTH=4,AM_PM=1,HOUR=11,HOUR_OF_DAY=23,MINUTE=11,SECOND=5,MILLISECOND=797,ZONE_OFFSET=28800000,DST_OFFSET=0]
//the OUTPUT tells that the month start from 0 instead of 1
//use get-method to get value of year,month,date
int year = c.get(Calendar.YEAR);//Calender.YEAR gives the int-type-parameter
int month = c.get(Calendar.MONTH)+1;//ATTENTION：add 1 here
int date = c.get(Calendar.DATE);
System.out.println(year+"年"+month+"月"+date+"日");//OUTPUT:2021年9月22日
}
}