Dinesh on Java

SimpleDateFormat is an excellent utility class for formatting and parsing dates in a re-presentable manner. It allows for formatting Date to String and parsing String to Date. SimpleDateFormat allows you to start by choosing any user-defined patterns for date-time formatting. It is not thread-safe so its better you create separate DateFormat for each thread to avoid any race condition while parsing date in java.SimpleDateFormat class has two methods format() method to format Date to String and parse() method parse String to Date and time in java. It is a concrete class for formatting and parsing date which inherits java.text.DateFormat class.

• format() formatting method means converting date to string
• parse() parsing method means converting string to date

 

 

There various attributes available in SimpleDateFormat class in java for pattern, As per Java Doc following:

Letter	Date or Time Component	Presentation	Examples
G	Era designator	Text	AD
y	Year	Year	1996; 96
M	Month in year	Month	July; Jul; 07
w	Week in year	Number	27
W	Week in month	Number	2
D	Day in year	Number	189
d	Day in month	Number	10
F	Day of week in month	Number	2
E	Day in week	Text	Tuesday; Tue
a	Am/pm marker	Text	PM
H	Hour in day (0-23)	Number	0
k	Hour in day (1-24)	Number	24
K	Hour in am/pm (0-11)	Number	0
h	Hour in am/pm (1-12)	Number	12
m	Minute in hour	Number	30
s	Second in minute	Number	55
S	Millisecond	Number	978
z	Time zone	General time zone	Pacific Standard Time; PST; GMT-08:00
Z	Time zone	RFC 822 time zone	-0800

SimpleDateFormat Example in Java

Format Date to String

In this example we are going to format dates using SimpleDateFormat. We can format Date to String to our defined format e.g “dd-MM-yyyy”. This format will print dates in that format e.g. 20-02-2017. We can define any format by using letter patterns supported by SimpleDateFormat in java e.g. d means day of month, y means year and M means Month of year as mention in above list in this tutorial. There following steps to convert date to string:

• Step 1: Create a valid date format using SimpleDateFormat as you wanna display upfront
• Step 2: Then call format() method of SimpleDateFormat and passed Date object as argument of this method, it will return String format of date as you specified in the first step.

Let’s see the simple example to format date in java using java.text.SimpleDateFormat class.

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * 
 */

/**
 * @author Dinesh.Rajput
 *
 */
public class SimpleDateFormatExample {

 /**
  * @param args
  */
 public static void main(String[] args) {
  //Creating Date in java with today's date.
    Date todayDate = new Date();

    //change date to string on dd-MM-yyyy format e.g. "20-02-2017"
    SimpleDateFormat dateformater_Java = new SimpleDateFormat("dd-MM-yyyy");
    String todayDateStr = dateformater_Java.format(todayDate);
    System.out.println("Today's date into dd-MM-yyyy format: " + todayDateStr);
    
    //converting date to string dd/MM/yyyy format for example "20/02/2017"
    SimpleDateFormat formatDateJava = new SimpleDateFormat("dd/MM/yyyy");
    todayDateStr = formatDateJava.format(todayDate);
    System.out.println("Today's date into dd/MM/yyyy format: " + todayDateStr);
      
    //change date into string yyyyMMdd format example "20170220"
    SimpleDateFormat dateformater_yyyyMMdd = new SimpleDateFormat("yyyyMMdd");
    todayDateStr = dateformater_yyyyMMdd.format(todayDate);
    System.out.println("Today's date into yyyyMMdd format: " + todayDateStr);

 }

}

Output:
Today’s date into dd-MM-yyyy format: 20-02-2017
Today’s date into dd/MM/yyyy format: 20/02/2017
Today’s date into yyyyMMdd format: 20170220

Parse String to Date

java.text.SimpleDateFormat class is also used to format Date to String as date and time. SimpleDateFormat formats date in same pattern whatever we are provided to it while creating instance of SimpleDateFormat. So we can also include time information like hour, minutes and seconds while formatting dates.

Let’s see the full example to format date and time in java using java.text.SimpleDateFormat class.

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * 
 */

/**
 * @author Dinesh.Rajput
 *
 */
public class SimpleDateFormatExample {

 /**
  * @param args
  */
 public static void main(String[] args) {
  
  //parse string to date dd/MM/yyyy format e.g. "20-02-2017"
  SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");  
  try {  
   Date date = formatter.parse("20/02/2017");  
         System.out.println("Date is: "+date);  
  } catch (ParseException e) {
   e.printStackTrace();
  }  
     
  //parse string to date dd-MM-yyyy format e.g. "20-02-2017"
  formatter = new SimpleDateFormat("dd-MM-yyyy");  
  try {  
   Date date = formatter.parse("20-02-2017");  
         System.out.println("Date is: "+date);  
  } catch (ParseException e) {
   e.printStackTrace();
  }  
     
       }

}

Output:
Date is: Mon Feb 20 00:00:00 IST 2017
Date is: Mon Feb 20 00:00:00 IST 2017

Summary
In this tutorial we have seen how to format date to string and parse string to date using SimpleDateFormat with example. There are two methods exists in this concrete class format() and parse(). format() used for formatting means converting date to string and parse() used for parsing means converting string to date.