Java SE basics-SimpleDateFormat (Date Format) and sesimpledateformat for common class libraries

Java SE basics-SimpleDateFormat (Date Format) and sesimpledateformat for common class libraries

Get the current date and format the input according to different dates. The Code is as follows:

1 // 20160618 SimpleDateFomat class use date formatting Exercise 2 package MyPackage; // custom package 3 4 import java. text. simpleDateFormat; // The SimpleDateFormat package required for import 5 import java. util. date; // import the required Date Package 6 7 class MyDateDemo {// defines the MyDateDemo class 8 private SimpleDateFormat sd = null; // declares the SimpleDateFormat object sd 9 10 public String getDate01 () {// define the getDate01 method 11 this. sd = new SimpleDateFormat ("yyyy-MM-dd HH: mm; ss. sss "); // get a" yyyy-MM-dd12 // HH: mm; ss. sss "format date 13 return this. sd. format (new Date (); // format the current Date 14} 15 16 public String getDate02 () {// define the getDate02 Method 17 this. sd = new SimpleDateFormat ("MM mm dd, yyyy hh mm mm ss s sss ms "); // get a format of "yyyy MM dd, yyyy, 18 // HH mm min ss sec sss millisecond" 19 return this. sd. format (new Date (); // format the current Date 20} 21 22 public String getDate03 () {// define the getDate03 Method 23 this. sd = new SimpleDateFormat ("yyyyMMddHHmmsssss"); // get a "yyyyMMddHHmmsssss" format date (that is, the timestamp) 24 return this. sd. format (new Date ()); // format the current date 25} 26} 27 28 public class SimpleDateFormatDemo {// main class 29 30 public static void main (String [] args) {// main method 31 MyDateDemo dd = new MyDateDemo (); // declare the dd object and instantiate the 32 System. out. println ("default Date format:" + new Date (); // call the method to enter a Date of different formats 33 System. out. println ("English Date Format:" + dd. getDate01 (); 34 System. out. println ("Chinese Date Format:" + dd. getDate02 (); 35 System. out. println ("timestamp:" + dd. getDate03 (); 36 37} 38 39}

 

There is another date formatting method, which is preferred. The code for another method is as follows:

 

1 import java. util. *; // import the required toolkit 2 class DateTime {// you can directly use this class to obtain the date and time 3 private Calendar calendar = null; // declare a Calendar Object, get time 4 public DateTime () {// The object is instantiated in the constructor 5 this. calendar = new GregorianCalendar (); 6} 7 public String getDate () {// you can get a date in the format of yyyy-MM-dd HH: mm: ss. SSS 8 // considering that the program needs to modify strings frequently, use StringBuffer to improve performance 9 StringBuffer buf = new StringBuffer (); 10 buf. append (calendar. get (Calendar. YEAR )). append ("-"); // increase the number of buckets by 11 years. append (this. addZero (calendar. get (Calendar. MONTH) + 1, 2 )). append ("-"); // increase by 12 buf months. append (this. addZero (calendar. get (Calendar. DAY_OF_MONTH), 2 )). append (""); // get the 13 buf. append (this. addZero (calendar. get (Calendar. HOUR_OF_DAY), 2 )). append (":"); // 14 buf. append (this. addZero (calendar. get (Calendar. MINUTE), 2 )). append (":"); 15 buf. append (this. addZero (calendar. get (Calendar. SECOND), 2 )). append (". "); 16 buf. append (this. addZero (calendar. get (Calendar. MILLISECOND), 3); 17 return buf. toString (); 18} 19 public String getDateComplete () {// get a date: format: MM minute ss second SSS millisecond 20 At HH on mm dd, yyyy // considering that the program needs to frequently modify the string, use StringBuffer to improve performance 21 StringBuffer buf = new StringBuffer (); 22 buf. append (calendar. get (Calendar. YEAR )). append ("year"); // increase by 23 buf. append (this. addZero (calendar. get (Calendar. MONTH) + 1, 2 )). append ("month"); // increase monthly buf. append (this. addZero (calendar. get (Calendar. DAY_OF_MONTH), 2 )). append ("day"); // get the 25 buf. append (this. addZero (calendar. get (Calendar. HOUR_OF_DAY), 2 )). append ("Hour"); // 26 buf. append (this. addZero (calendar. get (Calendar. MINUTE), 2 )). append ("points"); // score 27 buf. append (this. addZero (calendar. get (Calendar. SECOND), 2 )). append ("second"); // get second 28 buf. append (this. addZero (calendar. get (Calendar. MILLISECOND), 3 )). append ("millisecond"); // get millisecond 29 return buf. toString (); 30} 31 public String getTimeStamp () {// get a timestamp 32 // considering that the program needs to modify the String frequently, so use StringBuffer to improve performance 33 StringBuffer buf = new StringBuffer (); 34 buf. append (calendar. get (Calendar. YEAR); // increase by 35 buf. append (this. addZero (calendar. get (Calendar. MONTH) + 1, 2); // increase by 36 buckets per MONTH. append (this. addZero (calendar. get (Calendar. DAY_OF_MONTH), 2); // get the 37 buf. append (this. addZero (calendar. get (Calendar. HOUR_OF_DAY), 2); // 38 buf. append (this. addZero (calendar. get (Calendar. MINUTE), 2); // scored 39 buf. append (this. addZero (calendar. get (Calendar. SECOND), 2); // get the SECOND 40 buf. append (this. addZero (calendar. get (Calendar. MILLISECOND), 3); // get 41 return buf in milliseconds. toString (); 42} 43 // considering that there is a leading 0 in the date, add the method 44 private String addZero (int num, int len) with zeros here) {45 StringBuffer s = new StringBuffer (); 46 s. append (num); 47 while (s. length () <len) {// If the length is insufficient, add 048 s. insert (0, "0"); // Add 049} 50 return s at the first position. toString (); 51} 52}; 53 public class DateDemo06 {54 public static void main (String args []) {55 DateTime dt = new DateTime (); 56 System. out. println ("system date:" + dt. getDate (); 57 System. out. println ("Chinese Date:" + dt. getDateComplete (); 58 System. out. println ("timestamp:" + dt. getTimeStamp (); 59} 60 };

You can remember and use it frequently.