Java often uses date operations to explain the specifics

Date type Most of the time component calculation methods have been replaced by calendar
Date Regular usage settime getTime ()
new Date (); Gets the current time by default

SimpleDateFormat the detailed class used to format and parse dates
String that matches the date
Y–> year
M–> Month
D–> Day
E–> Week
A–> last Afternoon
H–> hours (24-hour system)
H–> hours (12-hour system)
M–> min
S–> sec

Format date return value to string

new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String result = sdf.format(newDate());System.out.println(result);

Output: 2015-07-22 21:17:43

Resolves a string to date

new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String"2015-07-22 21:21:01";Datedate = sdf.parse(strDate);System.out.println(date);

Output Result:
Wed Jul 21:21:01 CST 2015

Calender encapsulates the calendar information
Regular usage:
GetInstance () Gets the subclass of a calender in the region where the system is implemented
Often used to instantiate calendar
Set (int field,int value) setting time
Get (int field) gets the corresponding value of the time component
Getactualmaximum (int field) Gets the maximum value of the time component
Add () calculates the time component
SetTime and GetTime methods set and get time

Comprehensive application:
Product Promotion Calculation Program
Demand:
The user enters the product production date and shelf life. Calculate Promotion Date by program
Calculation rules:
Until the expiry date of the 14 Tim Wednesday is the promotion day

 Public classpromotiondate { Public Static void Main(string[] args) throws Exception {Calendar cd = Calendar.getinstance (); SimpleDateFormat SDF =NewSimpleDateFormat ("Yyyy-mm-dd"); Scanner sc =NewScanner (System.inch); System. out. Print ("Please enter the production date:"); Date productiondate= Sdf.parse (Sc.nextline ());//Receive string and convert to date typeSystem. out. Print ("Please enter the shelf life:");intDays = Sc.nextint ();        Cd.settime (productiondate); Cd.add (Calendar.day_of_year, (Days- -)); Cd.Set(Calendar.day_of_week, Calendar.wednesday); String promotiondate = Sdf.format (Cd.gettime ());//Date after format calculationSystem. out. println ("The promotion date for this product is:"+ promotiondate);    Sc.close (); }}

Test results:
Please enter production Date: 2015-01-01
Please enter the shelf life: 180
The promotion date for this product is: 2015-06-17

Java often uses date operations to explain the specifics