Java Date operation

Date class: (Class under the Java.util package)

1. How do I format an object of the date class to display the date as a custom format?

 PackageCom.zhaixiaobin.jobText.demo1;Importjava.text.ParseException;ImportJava.text.SimpleDateFormat;Importjava.util.Date; Public classDemo01 { Public Static voidMain (string[] args)throwsParseException {/** The date class under Java.util, showing the current time*/Date Date=NewDate ();                SYSTEM.OUT.PRINTLN (date); /** Use SimpleDateFormat class to format time, user-defined format*/System.out.println (); SimpleDateFormat SDF1=NewSimpleDateFormat ("Yyyy-mm-dd hh:mm:ss"); SimpleDateFormat SDF2=NewSimpleDateFormat ("Yyyy/mm/dd hh:mm:ss"); SimpleDateFormat sdf3=NewSimpleDateFormat ("yyyy mm month dd Day hh mm min ss sec"); String str1=Sdf1.format (date); String str2=Sdf2.format (date); String STR3=Sdf3.format (date);        System.out.println (STR1);        System.out.println (STR2);                System.out.println (STR3);        System.out.println (); /** Use the Parse method to display the string as a date*/String str= "2015-6-9 21:19:30"; SimpleDateFormat SDF=NewSimpleDateFormat ("Yyyy-mm-dd hh:mm:ss"); Date Now=sdf.parse (str);    System.out.println (now); }}

Output Result :

Wed June 10:32:08 CST 20162016-06-29 10:32:082016/06/29 10:32:082016 June 29 10:32 08 sec Tue June 21:19:30 CST 2015

Now generally tend to use the Calendar class

Calendar class (class under the Java.util package)

1> how to get an object of the Calendar class and get the year, month, day, time, minute, second

Use the getinstance () method to get a calendar object

Package Com.zhaixiaobin.jobtext.demo1;import Java.util.calendar;public class Demo02 {public     static void main ( String[] args) {Calendar c=calendar.getinstance ();  Create a Calendar object        int year=c.get (calendar.year);        int Month=c.get (calendar.month) +1; //0 means January, so add 1        int Day=c.get (calendar.day_of_month);        int Hour=c.get (calendar.hour_of_day);        int Minute=c.get (calendar.minute);        int Second=c.get (calendar.second);        System.out.println ("Now is:" +year+ "year" +month+ "month" +day+ "Day" + "+hour+" when "        +minute+" cent "+second+" seconds ");}}

Output Result:

Now is: June 29, 2016 10:51 16 seconds

2> since both the date class and the Calendar class can display the current date, how do you convert the date class and the Calendar class?

Package Com.zhaixiaobin.jobtext.demo1;import Java.text.simpledateformat;import Java.util.calendar;import Java.util.date;public class Demo03 {public static void main (string[] args) {Calendar c1=calendar.getinstance ();D ate Date2=c1.gettime ();
                Long time =c1.gettimeinmills ()//Gets the C1 value, in milliseconds SimpleDateFormat sdf5=new simpledateformat ("Yyyy-mm-dd hh:mm:ss");                String Now=sdf5.format (date2);                System.out.println ("Now is:" +now);

                System.out.println ("Now is:" +time+ "seconds");

} }

　　

Output Result:

Now is: 2016-06-29-11:00:50

Now is: 1,467,169,495,364 seconds

　　

Java Date operation