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

If you want to change formatting styles provided by DateFormat, you can uses 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.example.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: 12-Apr-2018
Canada | format: 12-Apr-2018
France | format: 12-avr.-2018
Germany | format: 12-Apr-2018
United States | format: 12-Apr-2018
Japan | format: 12-4-2018

How do I get default date and time format for a defined country?

The DateFormat class allows you to format dates and times with predefined styles in a locale-sensitive manner. Formatting dates or times with the DateFormat class is a two-step process.

First, you create a formatter with the getDateInstance() method for formatting date or getTimeInstance() method for formatting time or getDateTimeInstance() when you want formatting both date and time.

Second, you invoke the format method, which returns a String containing the formatted date. The following example formats today’s date and time by calling those two methods.

package org.kodejava.example.text;

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

public class LocaleDateTime {
    public static void main(String[] args) {
        Locale[] locales = {Locale.CANADA, Locale.FRANCE, Locale.GERMANY,
            Locale.US, Locale.JAPAN};

        Date today = new Date();
        for (Locale locale : locales) {
            StringBuilder sb = new StringBuilder();
            sb.append(locale.getDisplayCountry())
                .append(System.lineSeparator());
            sb.append("--------------------------------")
                .append(System.lineSeparator());

            // Gets a DateFormat instance for the specified locale
            // and format a date object by calling the format
            // method.
            DateFormat df = DateFormat.getDateInstance(DateFormat.DEFAULT, locale);
            String date = df.format(today);
            sb.append("Default date format: ").append(date)
                .append(System.lineSeparator());

            // Gets a DateFormat instance for the specified locale
            // and format a time information by calling the format
            // method.
            DateFormat tf = DateFormat.getTimeInstance(DateFormat.DEFAULT, locale);
            String time = tf.format(today.getTime());
            sb.append("Default time format: ").append(time)
                .append(System.lineSeparator());

            System.out.println(sb.toString());
        }

        // Gets date and time formatted value for Italy locale using
        // To display a date and time in the same String, create the
        // formatter with the getDateTimeInstance method.
        // The first parameter is the date style, and the second is
        // the time style. The third parameter is the Locale
        DateFormat dtf = DateFormat.getDateTimeInstance(DateFormat.DEFAULT,
            DateFormat.DEFAULT, Locale.ITALY);
        String datetime = dtf.format(today);

        System.out.println("date time format in " +
            Locale.ITALY.getDisplayCountry() + ": " + datetime);
    }
}

Here are the produces output:

Canada
--------------------------------
Default date format: 10-Apr-2018
Default time format: 10:18:11 PM

France
--------------------------------
Default date format: 10 avr. 2018
Default time format: 22:18:11

Germany
--------------------------------
Default date format: 10.04.2018
Default time format: 22:18:11

United States
--------------------------------
Default date format: Apr 10, 2018
Default time format: 10:18:11 PM

Japan
--------------------------------
Default date format: 2018/04/10
Default time format: 22:18:11

date time format in Italy: 10-apr-2018 22.18.11

How do I compare two dates?

In this example you’ll see the utilization of SimpleDateFormat class for comparing two dates for equality. We convert the date object into string using the DateFormat instance and then compare it using String.equals() method.

package org.kodejava.example.util;

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

public class ComparingDate {
    public static void main(String[] args) {
        // Create a SimpleDateFormat instance with dd/MM/yyyy format
        DateFormat df = new SimpleDateFormat("dd/MM/yyyy");

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

        // Create an instance of calendar that represents a new year date
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DATE, 1);
        calendar.set(Calendar.MONTH, Calendar.JANUARY);
        calendar.set(Calendar.YEAR, 2017);

        String now = df.format(today);
        String newYear = df.format(calendar.getTime());

        // Using the string equals method we can compare the date.
        if (now.equals(newYear)) {
            System.out.println("Happy New Year!");
        } else {
            System.out.println("Have a nice day!");
        }
    }
}

How do I check if a string is a valid date?

The following code can be use to validate if a string contains a valid date information. The pattern of the date is defined by the java.text.SimpleDateFormat object. When the date is not valid a java.text.ParseException will be thrown.

package org.kodejava.example.text;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.text.ParseException;

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

        // Input to be parsed should strictly follow the defined date format
        // above.
        format.setLenient(false);

        String date = "29/18/2017";
        try {
            format.parse(date);
        } catch (ParseException e) {
            System.out.println("Date " + date + " is not valid according to " +
                ((SimpleDateFormat) format).toPattern() + " pattern.");
        }
    }
}

The result of the above date validation code is:

Date 29/18/2017 is not valid according to dd/MM/yyyy pattern.

How do I change date formatting symbols?

This example shows how we can change the date formatting symbols. In this example we change the month names and short month names and also the weekday names and short weekday names.

Other than these two items we can also change other symbols such as the Era name and AM-PM string.

package org.kodejava.example.text;

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

public class DateFormatSymbolsExample {
    public static void main(String[] args) {
        // Defining a new Date Format Symbols, the following are month and day
        // names in Indonesian.
        String[] newMonths = {"JANUARI", "FEBRUARI", "MARET", "APRIL", "MEI",
            "JUNI", "JULI", "AGUSTUS", "SEPTEMBER", "OKTOBER", "NOVEMBER",
            "DESEMBER"};
        String[] newShortMonths = {"JAN", "FEB", "MAR", "APR", "MEI", "JUN",
            "JUL", "AGU", "SEP", "OKT", "NOV", "DES"};
        String[] newWeekdays = {"", "MINGGU", "SENIN", "SELASA", "RABU", "KAMIS",
            "JUMAT", "SABTU"};
        String[] shortWeekdays = {"", "MIN", "SEN", "SEL", "RAB", "KAM", "JUM",
            "SAB"};

        DateFormatSymbols symbols = new DateFormatSymbols();
        symbols.setMonths(newMonths);
        symbols.setShortMonths(newShortMonths);
        symbols.setWeekdays(newWeekdays);
        symbols.setShortWeekdays(shortWeekdays);

        DateFormat format = new SimpleDateFormat("dd MMMM yyyy", symbols);
        System.out.println(format.format(new Date()));

        format = new SimpleDateFormat("dd MMM yyyy", symbols);
        System.out.println(format.format(new Date()));

        format = new SimpleDateFormat("EEEE, dd MMM yyyy", symbols);
        System.out.println(format.format(new Date()));

        format = new SimpleDateFormat("E, dd MMM yyyy", symbols);
        System.out.println(format.format(new Date()));
    }
}

The result of the code snippet above is:

15 FEBRUARI 2018
15 FEB 2018
KAMIS, 15 FEB 2018
KAM, 15 FEB 2018

How do I convert milliseconds value to date?

package org.kodejava.example.util;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class MillisecondsToDate {
    public static void main(String[] args) {
        // Create a DateFormatter object for displaying date information.
        DateFormat formatter = new SimpleDateFormat("dd/MM/yyyy hh:mm:ss.SSS");

        // Get date and time information in milliseconds
        long now = System.currentTimeMillis();

        // Create a calendar object that will convert the date and time value
        // in milliseconds to date. We use the setTimeInMillis() method of the
        // Calendar object.
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(now);

        System.out.println(now + " = " + formatter.format(calendar.getTime()));
    }
}

How do I set default Locale?

package org.kodejava.example.util;

import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.Random;

public class DefaultLocaleExample {
    public static void main(String[] args) {
        // Use Random class to generate some random number
        Random random = new Random();

        // We use the system default locale to format a number and a date.
        NumberFormat formatter = new DecimalFormat();
        Locale locale = Locale.getDefault();
        System.out.println("Default Locale = " + locale);
        System.out.println("Number         = " + formatter.format(random.nextDouble()));
        System.out.println("Date           = " + new SimpleDateFormat().format(new Date()));

        // We change the default locale to Locale.ITALY by setting it through 
        // the Locale.setDefault() method and then we format another number 
        // and date using a new locale. This change will affect all the class 
        // that aware to the Locale, such as the NumberFormat class.
        Locale.setDefault(Locale.ITALY);
        NumberFormat newFormatter = new DecimalFormat();
        System.out.println("New Locale     = " + Locale.getDefault());
        System.out.println("Number         = " + newFormatter.format(random.nextDouble()));
        System.out.println("Date           = " + new SimpleDateFormat().format(new Date()));
    }
}

The result of the code snippet above are:

Default Locale = en_US
Number         = 0.78
Date           = 10/20/17 1:58 PM
New Locale     = it_IT
Number         = 0,068
Date           = 20/10/17 13.58

How do I convert string date to long value?

package org.kodejava.example.util;

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

public class StringDateToLong {
    public static void main(String[] args) {
        // Here we have a string date and we want to covert it to long value
        String today = "13/10/2017";

        // Create a SimpleDateFormat which will be use to convert the string to
        // a date object.
        DateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");
        try {
            // The SimpleDateFormat parse the string and return a date object.
            // To get the date in long value just call the getTime method of
            // the Date object.
            Date date = formatter.parse(today);
            long dateInLong = date.getTime();

            System.out.println("Date         = " + date);
            System.out.println("Date in Long = " + dateInLong);
        } catch (ParseException e) {
            e.printStackTrace();
        }
    }
}

The result of the code snippet:

Date         = Fri Oct 13 00:00:00 WITA 2017
Date in Long = 1507824000000

How do I format a date-time value?

In the DateFormat class there are some predefined constants that we can use to format a date time value. Here is an example of it.

package org.kodejava.example.text;

import java.text.DateFormat;
import java.util.Date;

public class DefaultDateFormatExample {
    public static void main(String[] args) {
        Date date = new Date();

        // Format date in a short format
        String today = DateFormat.getDateTimeInstance(DateFormat.SHORT,
                DateFormat.SHORT).format(date);
        System.out.println("Today " + today);

        // Format date in a medium format
        today = DateFormat.getDateTimeInstance(DateFormat.MEDIUM,
                DateFormat.MEDIUM).format(date);
        System.out.println("Today " + today);

        // Format date in a long format
        today = DateFormat.getDateTimeInstance(DateFormat.LONG,
                DateFormat.LONG).format(date);
        System.out.println("Today " + today);
    }
}

And you’ll see the result as follow:

Today 2/1/18, 9:13 PM
Today Feb 1, 2018, 9:13:20 PM
Today February 1, 2018 at 9:13:20 PM CST

How do I format a date into dd/MM/yyyy?

Formatting a display is a common requirement when creating a program. Information in a good format can be seen as an added value to the user of the program. Using Java SimpleDateFormat we can easily format a date in our program.

package org.kodejava.example.text;

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

public class DateFormatExample {
    public static void main(String[] args) {
        Date date = Calendar.getInstance().getTime();

        // Display a date in day, month, year format
        DateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");
        String today = formatter.format(date);
        System.out.println("Today : " + today);

        // Display date with day name in a short format
        formatter = new SimpleDateFormat("EEE, dd/MM/yyyy");
        today = formatter.format(date);
        System.out.println("Today : " + today);

        // Display date with a short day and month name
        formatter = new SimpleDateFormat("EEE, dd MMM yyyy");
        today = formatter.format(date);
        System.out.println("Today : " + today);

        // Formatting date with full day and month name and show time up to
        // milliseconds with AM/PM
        formatter = new SimpleDateFormat("EEEE, dd MMMM yyyy, hh:mm:ss.SSS a");
        today = formatter.format(date);
        System.out.println("Today : " + today);
    }
}

Let’s view what we got on the console:

Today : 28/01/2018
Today : Sun, 28/01/2018
Today : Sun, 28 Jan 2018
Today : Sunday, 28 January 2018, 03:09:43.293 PM