How to Format Dates with SimpleDateFormat

By I Wayan Saryada in Text Package 0 Comment

You can format dates in Java using the SimpleDateFormat class, which is part of the java.text package. This class allows you to specify patterns describing the formatting and parsing of date and time objects.

Here’s a step-by-step guide:

Example of Formatting Dates with SimpleDateFormat

package org.kodejava.text;

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

public class DateFormatExample {
   public static void main(String[] args) {
      // Create an instance of SimpleDateFormat
      // Specify the desired pattern
      SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");

      // Get the current date
      Date currentDate = new Date();

      // Format the date
      String formattedDate = simpleDateFormat.format(currentDate);

      // Print the result
      System.out.println("Formatted Date: " + formattedDate);
   }
}

Common Patterns for Date and Time Formatting

Here are some of the most commonly used patterns:

Symbol Description Example
y Year 2025
M Month in year 08 or August
d Day of the month 02
h Hour in AM/PM (1-12) 3
H Hour in day (0-23) 15
m Minute in hour 45
s Second in minute 30
S Millisecond 978
E Day of the week Tue
D Day of the year 214
z Time zone PDT
Z Time zone offset -0700

You can mix and match these symbols to create a pattern that suits your needs.

Example with Custom Pattern

SimpleDateFormat dateFormat = new SimpleDateFormat("EEEE, MMM dd, yyyy hh:mm a");
Date date = new Date();
System.out.println("Custom Formatted Date: " + dateFormat.format(date));

Output:

Custom Formatted Date: Saturday, Aug 02, 2025 10:30 AM

Notes:

  1. Thread Safety:
    SimpleDateFormat is not thread-safe. If you need to use it in a multithreaded environment, you should manage synchronization or use java.time.format.DateTimeFormatter, which is thread-safe and introduced in Java 8.

  2. For Java 8 and Later:
    If you’re using Java 8 or later, consider using the new java.time API (DateTimeFormatter) for better clarity and thread safety.

How do I get pattern string of a SimpleDateFormat?

By I Wayan Saryada in Core API, Text Package 0 Comment

To format a java.util.Date object we use the SimpleDateFormat class. To get back the string pattern that were used to format the date we can use the toPattern() method of this class.

package org.kodejava.text;

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

public class SimpleDateFormatToPattern {
    public static void main(String[] args) {
        SimpleDateFormat format = new SimpleDateFormat("EEEE, dd/MM/yyyy");

        // Gets a pattern string describing this date format used by the
        // SimpleDateFormat object.
        String pattern = format.toPattern();

        System.out.println("Pattern = " + pattern);
        System.out.println("Date    = " + format.format(new Date()));
    }
}

The result of the program will be as follow:

Pattern = EEEE, dd/MM/yyyy
Date    = Tuesday, 26/10/2021

How do I change the date format symbols for a specified locale?

By I Wayan Saryada in Core API, Text Package 0 Comment 
package org.kodejava.text;

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

public class ChangeDateFormatSymbols {
    public static void main(String[] args) {
        Locale id = new Locale("in", "ID");
        String pattern = "EEEE, dd MMM yyyy";
        Date today = new Date();

        // Gets formatted date specify by the given pattern for
        // Indonesian Locale no changes for default date format
        // is applied here.
        SimpleDateFormat sdf = new SimpleDateFormat(pattern, id);
        String before = sdf.format(today);
        System.out.println("Before format change: " + before);

        // Create a DateFormatSymbols object for Indonesian locale.
        DateFormatSymbols dfs = new DateFormatSymbols(id);

        // Gets String array of default format of weekdays.
        String[] days = dfs.getWeekdays();
        String[] newDays = new String[days.length];
        for (int i = 0; i < days.length; i++) {
            // For each day, apply toUpperCase() method to
            // capitalized it.
            newDays[i] = days[i].toUpperCase();
        }

        // Set String array of weekdays.
        dfs.setWeekdays(newDays);

        // Gets String array of default format of short months.
        String[] shortMonths = dfs.getShortMonths();
        String[] months = new String[shortMonths.length];
        for (int j = 0; j < shortMonths.length; j++) {
            // For each short month, apply toUpperCase() method
            // to capitalized it.
            months[j] = shortMonths[j].toUpperCase();
        }

        // Set String array of short months.
        dfs.setShortMonths(months);

        // Create a SimpleDateFormat object by given pattern and 
        // symbol and then format the date object as String.
        sdf = new SimpleDateFormat(pattern, dfs);
        String after = sdf.format(today);
        System.out.println("After change format : " + after);
    }
}

Here are the output of our program:

Before format change: Selasa, 19 Okt 2021
After change format : SELASA, 19 OKT 2021

How do I get a formatted date for a specific pattern and locale?

By I Wayan Saryada in Core API, Text Package 0 Comment

If you want to change formatting styles provided by DateFormat, you can use SimpleDateFormat class. The SimpleDateFormat class is locale-sensitive.

If you instantiate SimpleDateFormat without a Locale parameter, it will format the date and time according to the default Locale. Both the pattern and the Locale determine the format. For the same pattern, SimpleDateFormat may format a date and time differently if the Locale varies.

package org.kodejava.text;

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

public class SimpleDateFormatChangeLocalePattern {
    public static void main(String[] args) {
        String pattern = "dd-MMM-yyyy";
        Date today = new Date();

        // Gets a formatted date according to the given pattern.
        // Here only the pattern is passed as argument of the
        // SimpleDateFormat constructor, so it will format the
        // date according to the default Locale.
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        String local = sdf.format(today);
        System.out.println("Date in default locale: " + local);

        Locale[] locales = {
                Locale.CANADA,
                Locale.FRANCE,
                Locale.GERMANY,
                Locale.US,
                Locale.JAPAN
        };

        for (Locale locale : locales) {
            // Format a date according to the given pattern for each locale.
            sdf = new SimpleDateFormat(pattern, locale);
            String after = sdf.format(today);
            System.out.println(locale.getDisplayCountry() + " | format: " + after);
        }
    }
}

Here are the variety of output produces when formatting a date in the same date pattern but varies in Locale

Date in default locale: 19-Oct-2021
Canada | format: 19-Oct.-2021
France | format: 19-oct.-2021
Germany | format: 19-Okt.-2021
United States | format: 19-Oct-2021
Japan | format: 19-10月-2021

How do I format date using a locale based format?

By I Wayan Saryada in Core API, Text Package 0 Comment

The code below demonstrate how to format date information for a specific locale. In the example utilize the java.text.SimpleDateFormat class.

package org.kodejava.text;

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

public class FormatDateLocale {
    public static void main(String[] args) {
        // Defines an array of Locale we are going to use for
        // formatting date information.
        Locale[] locales = new Locale[] {
            Locale.JAPAN,
            Locale.CHINA,
            Locale.KOREA,
            Locale.TAIWAN,
            Locale.ITALY,
            Locale.FRANCE,
            Locale.GERMAN
        };

        // Get an instance of current date time
        Date today = new Date();

        // Iterates the entire Locale defined above and create a long
        // formatted date using the SimpleDateFormat.getDateInstance()
        // with the format, the Locale and the date information.
        for (Locale locale : locales) {
            System.out.printf("Date format in %s = %s%n",
                locale.getDisplayName(), SimpleDateFormat.getDateInstance(
                    SimpleDateFormat.LONG, locale).format(today));
        }
    }
}

The result of our code are:

Date format in Japanese (Japan) = 2021年10月6日
Date format in Chinese (China) = 2021年10月6日
Date format in Korean (South Korea) = 2021년 10월 6일
Date format in Chinese (Taiwan) = 2021年10月6日
Date format in Italian (Italy) = 6 ottobre 2021
Date format in French (France) = 6 octobre 2021
Date format in German = 6. Oktober 2021