I genius the official free tutorial 23: Java Common class Date class SimpleDateFormat class Calendar class

Date class

Gets the system current time by default when creating an object

SimpleDateFormat class

Used to format the date; The creation object can be passed in the format: New SimpleDateFormat ("Yyyy-mm-dd hh:mm:ss"); Main method Format (date)

Calendar class

You can use the Getcalendar () method in the SimpleDateFormat class to get the object. Common methods: Get (int); Common properties: Year MONTH ...

Example: Package common_class;import java.text.simpledateformat;import java.util.calendar;import  java.util.Date;/** *  Demo Date-related classes  *  @author   Genius Federation  -  Yukun  */public  Class datedemo {public static void main (String[] args)  {//Create Date Class object, The default is to get the system current Time date date = new date ();/* *  Create the formatted date class object  *  parameter for the date format that you want to output  * YYYY: Year  * mm: Month, be sure to capitalize  * DD: date, be sure to lowercase  * hh: hours  * mm: minutes, be sure to lowercase  * ss: seconds, be sure to lowercase  */simpledateformat sdf = new simpledateformat ("yyyy-MM-dd  hh:mm:ss ");//default is the International date format; output result: sun jun 14 01:17:56 cst 2015system.out.println (date );//Format Date String datestr = sdf.format (date);//Output Result: 2015-06-14 01:22:27system.out.println ( DATESTR);//Gets the Calendar class object Calendar calendar = sdf.getcalendar ();//Gets the month and day time of the second int year =  Calendar.get (calendar.year);///NOTE: Get monthThe value is Int month = calendar.get starting from 0 (calendar.month); Int day = calendar.get ( Calendar.date); Int hour = calendar.get (Calendar.hour); Int minute = calendar.get ( Calendar.minute); Int second = calendar.get (calendar.second);//output result: June 14, 2015    1:31 10 sec System.out.println (year +  "Year"  +  (month + 1)  +  "Month"  +  day +  "Day   "  + hour +  "Time"  + minute +  "Minute"  +  second +  "seconds");}} Running Result: thu jun 25 00:39:00 cst 20152015-06-25 12:39:002015 June 25    0:39 0 sec

Note: When using the SimpleDateFormat class, the case of the letter in the passed format string parameter should not be written incorrectly;
The month that you get with the Calendar class starts with 0

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I genius the official free tutorial 23: Java Common class Date class SimpleDateFormat class Calendar class