Java SimpleDateFormat | Set 1

SimpleDateFormat class helps in formatting and parsing of data. We can change date from one format to other. It allows to user to interpret string date format into a Date object. We can modify Date accordingly, we want.

Declaration : 

public class SimpleDateFormat
extends DateFormat

Constructors :

• SimpleDateFormat(String pattern_arg) : Constructs a Simple Date Format using the given pattern – pattern_arg, default date format symbols for the default FORMAT locale.
• SimpleDateFormat(String pattern_arg, Locale locale_arg) : Constructs a Simple Date Format using the given pattern – pattern_arg, default date format symbols for the given FORMAT Locale – locale_arg.
• SimpleDateFormat(String pattern_arg, DateFormatSymbols formatSymbols) : Constructs a SimpleDateFormat using the given pattern – pattern_arg and date format symbols.

Java Program illustrating SimpleDateFormat class

Java

// Java Program illustrating SimpleDateFormat class
import java.text.*;
import java.util.*;

public class NewClass
{
    public static void main(String[] args)
    {
        SimpleDateFormat geek = new SimpleDateFormat("dd / MM / yy");

        // Creating instance of the System date
        Calendar c = Calendar.getInstance();
        System.out.println("Present Date : " + c.getTime());

        // Formatting Date according "dd / MM / yy"
        String formattedDate = geek.format(c.getTime());
        System.out.println("Date formatted : "+formattedDate);

    }
}

Output: 

Present Date : Wed Jun 21 18:21:13 IST 2017
Date formatted : 21 / 06 / 17

Methods : 

1. set2DigitYearStart() : java.text.SimpleDateFormat.set2DigitYearStart(Date starting_Date) parses the date and set the date in the range starting_Date to starting_Date + 100 years. 

Syntax :

public void set2DigitYearStart(Date starting_Date)
Parameters :
starting_Date : Date is set in the range - starting_Date to starting_Date + 100 years
Return  :
Returns void

Java

// Java Program illustrating
// use of set2DigitYearStart() method

import java.text.*;
import java.util.Calendar;

public class NewClass
{
    public static void main(String[] args) throws InterruptedException
    {
        SimpleDateFormat geek = new SimpleDateFormat("MM / dd / yy");
        try
        {
            Calendar c = Calendar.getInstance();
            c.setTime(geek.parse("10 / 27 / 16"));
            System.out.println("Initial Time : "+c.getTime());

            // Setting 1916 instead of 2016
            // Use of set2DigitYearStart() method
            geek.set2DigitYearStart(geek.parse("01 / 01 / 1900"));

            c.setTime(geek.parse("06 / 12 / 16"));
            System.out.println("New Time : "+c.getTime());

        }
        catch (ParseException except)
        {
            except.printStackTrace();
        }
    }
}

Output : 

Initial Time : Thu Oct 27 00:00:00 IST 2016
New Time : Mon Jun 12 00:00:00 IST 1916

2. get2DigitYearStart() : java.text.SimpleDateFormat.get2DigitYearStart() returns start of 100 year period that was set during parsing. 

Syntax :

public void get2DigitYearStart()
Parameters :
-----
Return  :
Returns start of 100 year period that was set during parsing.

Implementation : 

Java

// Java Program illustrating
// use of get2DigitYearStart() method

import java.text.*;
import java.util.Calendar;

public class NewClass
{
    public static void main(String[] args) throws InterruptedException
    {
        SimpleDateFormat geek = new SimpleDateFormat("MM / dd / yy");
        try
        {
            Calendar c = Calendar.getInstance();
            c.setTime(geek.parse("10 / 27 / 16"));
            System.out.println("Initial Time : "+c.getTime());

            // Setting 1916 instead of 2016
            // Use of set2DigitYearStart() method
            geek.set2DigitYearStart(geek.parse("01 / 01 / 1900"));
            // Start Year is 1990.

            c.setTime(geek.parse("06 / 12 / 16"));
            System.out.println("New Time : "+c.getTime());

            // Use of get2DigitYearStart() method to check start year
            c.setTime(geek.get2DigitYearStart());
            System.out.println("START Year : "+c.get(Calendar.YEAR));

        }
        catch (ParseException except)
        {
            except.printStackTrace();
        }
    }
}

Output : 

Initial Time : Thu Oct 27 00:00:00 IST 2016
New Time : Mon Jun 12 00:00:00 IST 1916
START Year : 1900

3. toPattern() : java.text.SimpleDateFormat.toPattern() returns pattern of the Date format. 

Syntax :

public String toPattern()
Parameters :
-----
Return  :
Returns pattern of the Date format.

Java

// Java Program illustrating use of toPattern() method

import java.text.*;
import java.util.Calendar;

public class NewClass
{
    public static void main(String[] args) throws InterruptedException
    {
        SimpleDateFormat geek = new SimpleDateFormat();

        // Initializing Calendar object
        Calendar c = Calendar.getInstance();

        // getting Current Date
        String dateToday = geek.format(c.getTime());

        System.out.println("Current Date : "+dateToday);

        // Use of toPattern() method
        // Printing Date Pattern
        System.out.println("Date Pattern : "+geek.toPattern());

    }
}

Output :

Current Date : 6/21/17 6:24 PM
Date Pattern : M/d/yy h:mm a

4. parse() : java.text.SimpleDateFormat.parse() parses text from a string to form Date. It is specified by parse in class SimpleDateFormat. 

Syntax :

public Date parse()
Parameters :
-----
Return  :
Returns Date parsed from a string.

Java

// Java Program illustrating
// use of parse() method

import java.text.*;
import java.util.Calendar;

public class NewClass
{
    public static void main(String[] args) throws InterruptedException
    {
        SimpleDateFormat geek = new SimpleDateFormat("MM / dd / yy");
        try
        {
            Calendar c = Calendar.getInstance();

            // Use of .parse() method to parse Date From String 's'
            String s = "10 / 27 / 16" ;

            c.setTime(geek.parse(s));
            System.out.println("Time parsed from String : "+c.getTime());
        }
        catch (ParseException except)
        {
            except.printStackTrace();
        }
    }
}

Output : 

Time parsed from String : Thu Oct 27 00:00:00 IST 2016

5. applyPattern() : java.text.SimpleDateFormat.applyPattern(String arg) is used to set a defined pattern to the Date Format. 

Syntax :

public void applyPattern(String arg)
Parameters :
arg : defined pattern to be set to the Date Format.
Return  :
Void

Implementation : 

Java

// Java Program illustrating
// use of applyPattern() method

import java.text.*;
import java.util.Calendar;
public class NewClass
{
    public static void main(String[] args) throws InterruptedException
    {
        SimpleDateFormat geek = new SimpleDateFormat();

        // Initializing calendar Object
        Calendar c = Calendar.getInstance();

        // Using 'arg' pattern
        String arg = "dd / MM / yyyy HH:mm Z";

        // Use of applyPattern() method to set date to 'arg' format
        geek.applyPattern(arg);

        // current date and time
        String currentdate = geek.format(c.getTime());
        System.out.println("Current Date : "+currentdate);

        // Print the pattern being used
        System.out.println("Pattern applied : "+geek.toPattern());
    }
}

Output :

Current Date : 21 / 06 / 2017 18:25 +0530
Pattern applied : dd / MM / yyyy HH:mm Z

6. format() : java.text.SimpleDateFormat.format(Date arg) changes Date or Time to string.

Syntax :

public final String format(Date arg)
Parameters :
arg : Date to be formatted to String
Return  :
Formatted String of Date

Java

// Java Program illustrating
// use of format() method

import java.text.*;
import java.util.Calendar;

public class NewClass
{
    public static void main(String[] args) throws InterruptedException
    {
        SimpleDateFormat geek = new SimpleDateFormat();

        // Initializing calendar Object
        Calendar c = Calendar.getInstance();

        System.out.println("Actual Date : "+c.getTime());

        // Use of format() method to format Date to String
        String currentdate = geek.format(c.getTime());
        System.out.println("Formatted Date to String : "+currentdate);

    }
}

Output :

Actual Date : Wed Jun 21 18:25:50 IST 2017
Formatted Date to String : 6/21/17 6:25 PM

7. toLocalizedPattern() : java.text.SimpleDateFormat.toLocalizedPattern() returns Date pattern String of the Date Formatter. 

Syntax :

public String toLocalizedPattern()
Parameters :
------
Return  :
Date pattern String used in the formatter

Java

// Java Program illustrating
// use of toLocalizedPattern() method

import java.text.*;
import java.util.Calendar;

public class NewClass
{
    public static void main(String[] args) throws InterruptedException
    {
        // Date Formatter
        SimpleDateFormat geek = new SimpleDateFormat();

        // Initializing calendar Object
        Calendar c = Calendar.getInstance();

        System.out.println("Date : " + geek.format(c.getTime()));

        // Use of format() method to format Date to String
        System.out.println("Pattern in DateFormater 'geek' :"
                             + geek.toLocalizedPattern());

    }
}

Output :

Date : 6/21/17 6:27 PM
Pattern in DateFormater 'geek' : M/d/yy h:mm a

Next: Java.text.SimpleDateFormat class | Set 2