Java Internalization - Quick Guide

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Java Internalization - Overview

Internalization

Internalization or I18N refers to the capability of an Application to be able to serve users in multiple and different languages. Java has in-built support for Internalization. Java also provides formatting of numbers, currencies and adjustment of date and time accordingly.

Java Internationalization helps to make a java application handle different languages, number formats, currencies, region specific time formatting.

Localization

Localization or L10N is the adaptability of an application that is how an application adapts itself with a specific language, number formats, date and time settings etc.

A java application should be internationalized in order to be able to localize itself.

Culturally Dependent Information

Following information items often varies with different time zones or cultures.

• Messages

• Date

• Time

• Number

• Currency

• Measurements

• Phone Numbers

• Postal Addresses

• GUI labels

Internationalization Classes

Java has a set of built-in classes which help in internationalization of an application. These classes are following:

Java Internalization - Environment Setup

In this chapter, we will discuss on the different aspects of setting up a congenial environment for Java.

Local Environment Setup

If you are still willing to set up your environment for Java programming language, then this section guides you on how to download and set up Java on your machine. Following are the steps to set up the environment.

Java SE is freely available from the link Download Java. You can download a version based on your operating system.

Follow the instructions to download Java and run the .exe to install Java on your machine. Once you installed Java on your machine, you will need to set environment variables to point to correct installation directories −

Setting Up the Path for Windows

Assuming you have installed Java in c:\Program Files\java\jdk directory −

• Right-click on 'My Computer' and select 'Properties'.

• Click the 'Environment variables' button under the 'Advanced' tab.

• Now, alter the 'Path' variable so that it also contains the path to the Java executable. Example, if the path is currently set to 'C:\WINDOWS\SYSTEM32', then change your path to read 'C:\WINDOWS\SYSTEM32;c:\Program Files\java\jdk\bin'.

Setting Up the Path for Linux, UNIX, Solaris, FreeBSD

Environment variable PATH should be set to point to where the Java binaries have been installed. Refer to your shell documentation, if you have trouble doing this.

Example, if you use bash as your shell, then you would add the following line to the end of your '.bashrc: export PATH = /path/to/java:$PATH'

Popular Java Editors

To write your Java programs, you will need a text editor. There are even more sophisticated IDEs available in the market. But for now, you can consider one of the following −

• Notepad − On Windows machine, you can use any simple text editor like Notepad (Recommended for this tutorial), TextPad.

• Netbeans − A Java IDE that is open-source and free which can be downloaded from https://www.netbeans.org/index.html.

• Eclipse − A Java IDE developed by the eclipse open-source community and can be downloaded from https://www.eclipse.org/.

What is Next?

Next chapter will teach you how to write and run your first Java program and some of the important basic syntaxes in Java needed for developing applications.

Java Internalization - Locale Class

A Locale object represents a specific geographical/political/cultural region. Any operation requiring a Locale to perform its task is called locale-sensitive operation and uses the Locale to master information relative to the user. For example, displaying a number is a locale-sensitive operation. The number should be formatted as per the customs and conventions of the user's native country, region, or culture.

Locale Contents

A Locale object contains the following:

• Language - ISO 639 alpha-2 or alpha-3 language code, or registered language subtags up to 8 alpha letters. alpha-2 code must be used if both alpha-2 and alpha-3 code are present. The language field is case insensitive, but Locale always canonicalizes to lower case.

• Script - ISO 15924 alpha-4 script code. The script field is case insensitive, but Locale always canonicalizes to title case.

• Country (region) - ISO 3166 alpha-2 country code or UN M.49 numeric-3 area code. The country field is case insensitive, but Locale always canonicalizes to upper case.

• Variant - Any arbitrary value used to indicate a variation of a Locale. Where there are two or more variant values each indicating its own semantics, these values should be ordered by importance, with most important first, separated by underscore('_'). The variant field is case sensitive.

• Extensions - A map from single character keys to string values, indicating extensions apart from language identification. The extensions in Locale implement the semantics and syntax of BCP 47 extension subtags and private use subtags. The extensions are case insensitive, but Locale canonicalizes all extension keys and values to lower case.

Java Internalization - Example - Locale Details

In this example, we'll get default locale and print its details. Then create a locale for "fr" and print its details.

I18NTester.java

import java.util.Locale;

public class I18NTester {
   public static void main(String[] args) {
      Locale locale =Locale.getDefault();  

      System.out.println("Default Locale Properties:\n");

      System.out.println(locale.getDisplayCountry());  
      System.out.println(locale.getDisplayLanguage());  
      System.out.println(locale.getDisplayName());  
      System.out.println(locale.getISO3Country());  
      System.out.println(locale.getISO3Language());  
      System.out.println(locale.getLanguage());  
      System.out.println(locale.getCountry());  

      Locale frenchLocale = new Locale("fr","fr");

      System.out.println("\nfr Locale Properties:\n");
      System.out.println(frenchLocale.getDisplayCountry());  
      System.out.println(frenchLocale.getDisplayLanguage());  
      System.out.println(frenchLocale.getDisplayName());  
      System.out.println(frenchLocale.getISO3Country());  
      System.out.println(frenchLocale.getISO3Language());  
      System.out.println(frenchLocale.getLanguage());  
      System.out.println(frenchLocale.getCountry());  
   }
}

Output

It will print the following result.

Default Locale Properties:

United States
English
English (United States)
USA
eng
en
US

fr Locale Properties:

France
French
French (France)
FRA
fra
fr
FR

Java Internalization - Example - Display Language

In this example, we'll get display language per locale passed as an argument.

I18NTester.java

import java.util.Locale;

public class I18NTester {
   public static void main(String[] args) {
      Locale defaultLocale = Locale.getDefault();
      Locale enLocale = new Locale("en", "US");  
      Locale frLocale = new Locale("fr", "FR");  
      Locale esLocale = new Locale("es", "ES");

      System.out.println(defaultLocale.getDisplayLanguage(enLocale));
      System.out.println(defaultLocale.getDisplayLanguage(frLocale));
      System.out.println(defaultLocale.getDisplayLanguage(esLocale));
   }
}

Output

It will print the following result.

English
anglais
inglés

Java Internalization - ResourceBundle Class

ResourceBundle class is used to store text and objects which are locale sensitive. Generally we use property files to store locale specific text and then represent them using ResourceBundle object. Following are the steps to use locale specific properties file in a java based application.

Step 1: Create properties files.

Suppose we need properties file for English locale. Then create a properties file name XXX_en_US.properties where XXX is the name of the file and en_US represents the locale for English(US).

Messages_en_US.properties

message=Welcome to TutorialsPoint.COM!

Let's now create properties file for French locale. Then create a properties file name XXX_fr_FR.properties where XXX is the name of the file and fr_FR represents the locale for French(France).

Messages_fr_FR.properties

message=Bienvenue sur TutorialsPoint.COM!

Here you can figure out that the key is same but the value is locale specific in both the properties file.

Step 2: Create ResourceBundle object

Create ResourceBundle object with properties file name and locale using following syntax.

ResourceBundle bundle = ResourceBundle.getBundle("Messages", Locale.US);

Step 3: Get the value from ResourceBundle object.

Get the value from ResourceBundle object by passing the key.

String value = bundle.getString("message");

Example

Following example illustrate the use of ResourceBundle objects to display locale specific values from properties files.

IOTester.java

import java.util.Locale;
import java.util.ResourceBundle;

public class I18NTester {
   public static void main(String[] args) {
      ResourceBundle bundle = ResourceBundle.getBundle("Messages", Locale.US);  
      System.out.println("Message in "+Locale.US +": "+bundle.getString("message"));  

      bundle = ResourceBundle.getBundle("Messages", Locale.FRANCE);  
      System.out.println("Message in "+Locale.FRANCE +": "+bundle.getString("message"));
   }
}

Output

It will print the following result.

Message in en_US: Welcome to TutorialsPoint.COM!
Message in fr_FR: Bienvenue sur TutorialsPoint.COM!

Notes for Naming Conventions

Following are the naming conventions for the properties file.

• For properties file mapped to default locale, no prefix is mandatory. message_en_US.properties is equivalent to message.properties.

• For properties file mapped to locale, prefix can be attached in two ways. message_fr.properties is equivalent to message_fr_FR.properties.

Java Internalization - NumberFormat Class

The java.text.NumberFormat class is used for formatting numbers and currencies as per a specific Locale. Number formats varies from country to country. For example, In Denmark fractions of a number are separated from the integer part using a comma whereas in England they use a dot as separator.

Example - Format Numbers

In this example, we're formatting numbers based on US locale and Danish Locale.

IOTester.java

import java.text.NumberFormat;
import java.util.Locale;

public class I18NTester {
   public static void main(String[] args) {
      Locale enLocale = new Locale("en", "US");  
      Locale daLocale = new Locale("da", "DK");

      NumberFormat numberFormat = NumberFormat.getInstance(daLocale);

      System.out.println(numberFormat.format(100.76));

      numberFormat = NumberFormat.getInstance(enLocale);

      System.out.println(numberFormat.format(100.76));
   }
}

Output

It will print the following result.

100,76
100.76

Java Internalization - Format Currencies

In this example, we're formatting currencies based on US locale and Danish Locale.

IOTester.java

import java.text.NumberFormat;
import java.util.Locale;

public class I18NTester {
   public static void main(String[] args) {
      Locale enLocale = new Locale("en", "US");  
      Locale daLocale = new Locale("da", "DK");

      NumberFormat numberFormat = NumberFormat.getCurrencyInstance(daLocale);

      System.out.println(numberFormat.format(100.76));

      numberFormat = NumberFormat.getCurrencyInstance(enLocale);

      System.out.println(numberFormat.format(100.76));
   }
}

Output

It will print the following result.

kr 100,76
$100.76

Java Internalization - Format Percentages

In this example, we're formatting numbers in percentage format.

IOTester.java

import java.text.NumberFormat;
import java.util.Locale;

public class I18NTester {
   public static void main(String[] args) {
      Locale enLocale = new Locale("en", "US");        

      NumberFormat numberFormat = NumberFormat.getPercentInstance(enLocale);

      System.out.println(numberFormat.format(0.76));    
   }
}

Output

It will print the following result.

76%

Java Internalization - Set Min/Max Precision

In this example, we're setting min and max digits for both integer as well as fractional part of a number.

IOTester.java

import java.text.NumberFormat;
import java.util.Locale;

public class I18NTester {
   public static void main(String[] args) {
      Locale enLocale = new Locale("en", "US");  

      NumberFormat numberFormat = NumberFormat.getInstance(enLocale);
      numberFormat.setMinimumIntegerDigits(2);
      numberFormat.setMaximumIntegerDigits(3);

      numberFormat.setMinimumFractionDigits(2);
      numberFormat.setMaximumFractionDigits(3);

      System.out.println(numberFormat.format(12234.763443));
   }
}

Output

It will print the following result.

234.763

Java Internalization - Set Rounding Mode

In this example, we're showcasing Rounding Mode.

IOTester.java

import java.math.RoundingMode;
import java.text.NumberFormat;
import java.util.Locale;

public class I18NTester {
   public static void main(String[] args) {
      Locale enLocale = new Locale("en", "US");  
 
      NumberFormat numberFormat = NumberFormat.getInstance(enLocale);

      numberFormat.setMinimumFractionDigits(0);
      numberFormat.setMaximumFractionDigits(0);

      System.out.println(numberFormat.format(99.50));

      numberFormat.setRoundingMode(RoundingMode.HALF_DOWN);

      System.out.println(numberFormat.format(99.50));
   }
}

Output

It will print the following result.

100
99

Java Internalization - Parsing Numbers

In this example, we're showcasing parsing of number present in different locale.

IOTester.java

import java.text.NumberFormat;
import java.text.ParseException;
import java.util.Locale;

public class I18NTester {
   public static void main(String[] args) throws ParseException {
      Locale enLocale = new Locale("en", "US");  
      Locale daLocale = new Locale("da", "DK");

      NumberFormat numberFormat = NumberFormat.getInstance(daLocale);

      System.out.println(numberFormat.parse("100,76"));

      numberFormat = NumberFormat.getInstance(enLocale);

      System.out.println(numberFormat.parse("100,76"));
   }
}

Output

It will print the following result.

100.76
10076

Java Internalization - DecimalFormat Class

The java.text.DecimalFormat class is used for formatting numbers as per customized format and as per locale.

Example - Format Numbers

In this example, we're formatting numbers based on a given pattern.

IOTester.java

import java.text.DecimalFormat;

public class I18NTester {
   public static void main(String[] args) {
      String pattern = "####,####.##";
      double number = 123456789.123;
      
      DecimalFormat numberFormat = new DecimalFormat(pattern);

      System.out.println(number);
      
      System.out.println(numberFormat.format(number));
   }
}

Output

It will print the following result.

1.23456789123E8
1,2345,6789.12

Java Internalization - Format Patterns

Followings is the use of characters in formatting patterns.

In this example, we're formatting numbers based on different patterns.

IOTester.java

import java.text.DecimalFormat;

public class I18NTester {
   public static void main(String[] args) {
      String pattern = "###.###";
      double number = 123456789.123;

      DecimalFormat numberFormat = new DecimalFormat(pattern);

      System.out.println(number);

      //pattern ###.###
      System.out.println(numberFormat.format(number));

      //pattern ###.#
      numberFormat.applyPattern("###.#");
      System.out.println(numberFormat.format(number));

      //pattern ###,###.##
      numberFormat.applyPattern("###,###.##");
      System.out.println(numberFormat.format(number));

      number = 9.34;

      //pattern 000.###
      numberFormat.applyPattern("000.##");
      System.out.println(numberFormat.format(number));           
   }
}

Output

It will print the following result.

1.23456789123E8
1,2345,6789.12

Java Internalization - Locale Specific DecimalFormat

By default, DecimalFormat object is using the JVM's locale. We can change the default locale while creating the DecimalFormat object using NumberFormat class. In the example below, we'll use same pattern for two different locale and you can spot the difference in the output.

IOTester.java

import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.Locale;

public class I18NTester {
   public static void main(String[] args) {
      String pattern = "###.##";
      double number = 123.45;

      Locale enlocale  = new Locale("en", "US");
      Locale dalocale  = new Locale("da", "DK");

      DecimalFormat decimalFormat = (DecimalFormat) NumberFormat.getNumberInstance(enlocale);
      decimalFormat.applyPattern(pattern);

      System.out.println(decimalFormat.format(number));
   

      decimalFormat = (DecimalFormat) NumberFormat.getNumberInstance(dalocale);
      decimalFormat.applyPattern(pattern);

      System.out.println(decimalFormat.format(number));     
   }
}

Output

It will print the following result.

123.45
123,45

Java Internalization - DecimalFormatSymbols Class

Using DecimalFormatSymbols class, the default separator symbols, grouping separator symbols etc. can be changed. Following example is illustrating the same.

IOTester.java

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;

public class I18NTester {
   public static void main(String[] args) {
      String pattern = "#,###.###";
      double number = 126473.4567;

      DecimalFormat decimalFormat = new DecimalFormat(pattern);

      System.out.println(decimalFormat.format(number));
   

      DecimalFormatSymbols decimalFormatSymbols = new DecimalFormatSymbols();
      decimalFormatSymbols.setDecimalSeparator(';');
      decimalFormatSymbols.setGroupingSeparator(':');

      decimalFormat = new DecimalFormat(pattern, decimalFormatSymbols);

      System.out.println(decimalFormat.format(number));
   }
}

Output

It will print the following result.

126,473.457
126:473;457

Java Internalization - Grouping Digits

Using setGroupingSize() method of DecimalFormat, default grouping of numbers can be changed. Following example is illustrating the same.

IOTester.java

import java.text.DecimalFormat;

public class I18NTester {
   public static void main(String[] args) {
      double number = 121223232473.4567;

      DecimalFormat decimalFormat = new DecimalFormat();

      System.out.println(number);
      System.out.println(decimalFormat.format(number));
   

      decimalFormat.setGroupingSize(4);
      System.out.println(decimalFormat.format(number));
   
   }
}

Output

It will print the following result.

1.212232324734567E11
121,223,232,473.457
1212,2323,2473.457

Java Internalization - DateFormat Class

java.text.DateFormat class formats dates as per the locale. As different coutries use different formats to display dates. This class is extremely useful in dealing with dates in internalization of application. Following example show how to create and use DateFormat Class.

IOTester.java

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

public class I18NTester {
   public static void main(String[] args) {
      Locale locale = new Locale("da","DK");

      DateFormat dateFormat = DateFormat.getDateInstance();

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getDateInstance(DateFormat.DEFAULT, locale);

      System.out.println(dateFormat.format(new Date()));
   }
}

Output

It will print the following result.

Nov 29, 2017
29-11-2017

Java Internalization - Formatting Dates

DateFormat class provides various formats to format the date. Following is list of some of the formats.

• DateFormat.DEFAULT

• DateFormat.SHORT

• DateFormat.MEDIUM

• DateFormat.LONG

• DateFormat.FULL

In following example we'll show how to use different formats.

IOTester.java

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

public class I18NTester {
   public static void main(String[] args) {
   
      DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.DEFAULT);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getDateInstance(DateFormat.SHORT);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getDateInstance(DateFormat.MEDIUM);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getDateInstance(DateFormat.LONG);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getDateInstance(DateFormat.FULL);

      System.out.println(dateFormat.format(new Date()));
  
  
   }
}

Output

It will print the following result.

Nov 29, 2017
11/29/17
Nov 29, 2017
November 29, 2017
Wednesday, November 29, 2017

Java Internalization - Formatting Time

DateFormat class provides various formats to format the time. DateFormat.getTimeInstance() method is to be used. See the example below.

In following example we'll show how to use different formats to format time.

IOTester.java

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

public class I18NTester {
   public static void main(String[] args) {
   
      DateFormat dateFormat = DateFormat.getTimeInstance(DateFormat.DEFAULT);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getTimeInstance(DateFormat.SHORT);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getTimeInstance(DateFormat.MEDIUM);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getTimeInstance(DateFormat.LONG);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getTimeInstance(DateFormat.FULL);

      System.out.println(dateFormat.format(new Date()));
  
  
   }
}

Output

It will print the following result.

4:11:21 PM
4:11 PM
4:11:21 PM
4:11:21 PM IST
4:11:21 PM IST

Java Internalization - Formatting Date and Time

DateFormat class provides various formats to format the date and time together. DateFormat.getDateTimeInstance() method is to be used. See the example below.

In following example we'll show how to use different formats to format date and time.

IOTester.java

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

public class I18NTester {
   public static void main(String[] args) {

      DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.MEDIUM);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG);

      System.out.println(dateFormat.format(new Date()));

      dateFormat = DateFormat.getDateTimeInstance(DateFormat.FULL, DateFormat.FULL);

      System.out.println(dateFormat.format(new Date()));
  

   }
}

Output

It will print the following result.

Nov 29, 2017 4:16:13 PM
11/29/17 4:16 PM
Nov 29, 2017 4:16:13 PM
November 29, 2017 4:16:13 PM IST
Wednesday, November 29, 2017 4:16:13 PM IST

Java Internalization - SimpleDateFormat Class

java.text.SimpleDateFormat class formats dates as per the given pattern. It is also used to parse dates from string where string contains date in mentioned format. See the following example of using SimpleDateFormat class.

IOTester.java

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

public class I18NTester {
   public static void main(String[] args) throws ParseException {
   
      String pattern = "dd-MM-yyyy";

      SimpleDateFormat simpleDateFormat = new SimpleDateFormat(pattern);

      Date date = new Date();

      System.out.println(date);
      System.out.println(simpleDateFormat.format(date));

      String dateText = "29-11-2017";

      date = simpleDateFormat.parse(dateText);

      System.out.println(simpleDateFormat.format(date));
   }
}

Output

It will print the following result.

Wed Nov 29 17:01:22 IST 2017
29-11-2017
29-11-2017

Java Internalization - Locale specific SimpleDateFormat

Locale can be used to create locale specific formatting over a pattern in SimpleDateFormat class. See the following example of using locale specific SimpleDateFormat class.

IOTester.java

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

public class I18NTester {
   public static void main(String[] args) throws ParseException {

      Locale locale = new Locale("da", "DK");
      String pattern = "EEEEE MMMMM yyyy";

      SimpleDateFormat simpleDateFormat = new SimpleDateFormat(pattern);

      Date date = new Date();

      System.out.println(date);
      System.out.println(simpleDateFormat.format(date));

      simpleDateFormat = new SimpleDateFormat(pattern,locale);

      System.out.println(simpleDateFormat.format(date));
   }
}

Output

It will print the following result.

Wed Nov 29 17:48:14 IST 2017
Wednesday November 2017
onsdag november 2017

Java Internalization - DecimalFormatSymbols Class

Using DecimalFormatSymbols class, the default separator symbols, grouping separator symbols etc. can be changed. Following example is illustrating the same.

IOTester.java

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;

public class I18NTester {
   public static void main(String[] args) {
      String pattern = "#,###.###";
      double number = 126473.4567;

      DecimalFormat decimalFormat = new DecimalFormat(pattern);

      System.out.println(decimalFormat.format(number));
   

      DecimalFormatSymbols decimalFormatSymbols = new DecimalFormatSymbols();
      decimalFormatSymbols.setDecimalSeparator(';');
      decimalFormatSymbols.setGroupingSeparator(':');

      decimalFormat = new DecimalFormat(pattern, decimalFormatSymbols);

      System.out.println(decimalFormat.format(number));
   }
}

Output

It will print the following result.

126,473.457
126:473;457

Java Internalization - Date Format Patterns

Followings is the use of characters in date formatting patterns.

In this example, we're formatting dates based on different patterns.

IOTester.java

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

public class I18NTester {
   public static void main(String[] args) throws ParseException {

      String pattern = "dd-MM-yy";
      SimpleDateFormat simpleDateFormat = new SimpleDateFormat(pattern);
      Date date = new Date();
      System.out.println(simpleDateFormat.format(date));

      pattern = "MM-dd-yyyy";
      simpleDateFormat = new SimpleDateFormat(pattern);
      System.out.println(simpleDateFormat.format(date));

      pattern = "yyyy-MM-dd HH:mm:ss";
      simpleDateFormat = new SimpleDateFormat(pattern);
      System.out.println(simpleDateFormat.format(date));

      pattern = "EEEEE MMMMM yyyy HH:mm:ss.SSSZ";
      simpleDateFormat = new SimpleDateFormat(pattern);
      System.out.println(simpleDateFormat.format(date));
}
}

Output

It will print the following result.

29-11-17
11-29-2017
2017-11-29 18:47:42
Wednesday November 2017 18:47:42.787+0530

Java Internalization - UTC

UTC stands for Co-ordinated Universal Time. It is time standard and is commonly used across the world. All time zones are computed comparatively with UTC as offset. For example, time in Copenhagen, Denmark is UTC + 1 means UTC time plus one hour. It is independent of Day light savings and should be used to store date and time in databases.

Conversion of time zones

Following example will showcase conversion of various time zones. We'll print hour of the day and time in milliseconds. First will vary and second will remain same.

IOTester.java

import java.text.ParseException;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.TimeZone;

public class I18NTester {
   public static void main(String[] args) throws ParseException {
   
      Calendar date = new GregorianCalendar();

      date.setTimeZone(TimeZone.getTimeZone("Etc/UTC"));
      date.set(Calendar.HOUR_OF_DAY, 12);

      System.out.println("UTC: " + date.get(Calendar.HOUR_OF_DAY));
      System.out.println("UTC: " + date.getTimeInMillis());

      date.setTimeZone(TimeZone.getTimeZone("Europe/Copenhagen"));
      System.out.println("CPH: " + date.get(Calendar.HOUR_OF_DAY));
      System.out.println("CPH: " + date.getTimeInMillis());

      date.setTimeZone(TimeZone.getTimeZone("America/New_York"));
      System.out.println("NYC: " + date.get(Calendar.HOUR_OF_DAY));
      System.out.println("NYC: " + date.getTimeInMillis());
   }
}

Output

It will print the following result.

UTC: 12
UTC: 1511956997540
CPH: 13
CPH: 1511956997540
NYC: 7
NYC: 1511956997540

Available Time Zones

Following example will showcase the time zones available with the system.

IOTester.java

import java.text.ParseException;
import java.util.TimeZone;

public class I18NTester {
   public static void main(String[] args) throws ParseException {
      String[] availableIDs = TimeZone.getAvailableIDs();

      for(String id : availableIDs) {
         System.out.println("Timezone = " + id);
      }
   }
}

Output

It will print the following result.

Timezone = Africa/Abidjan
Timezone = Africa/Accra
...
Timezone = VST

Java Internalization - Unicode Conversion from/to String

In java, text is internally stored in Unicode format. If input/output is in different format then conversion is required.

Conversion

Following example will showcase conversion of a Unicode String to UTF8 byte[] and UTF8 byte[] to Unicode byte[].

IOTester.java

import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.text.ParseException;

public class I18NTester {
   public static void main(String[] args) throws ParseException, UnsupportedEncodingException {

      String unicodeString = "\u00C6\u00D8\u00C5" ;

      //convert Unicode to UTF8 format
      byte[] utf8Bytes = unicodeString.getBytes(Charset.forName("UTF-8"));
      printBytes(utf8Bytes, "UTF 8 Bytes");

      //convert UTF8 format to Unicode
      String converted = new String(utf8Bytes, "UTF8");
      byte[] unicodeBytes = converted.getBytes();
      printBytes(unicodeBytes, "Unicode Bytes");
   }

   public static void printBytes(byte[] array, String name) {
      for (int k = 0; k < array.length; k++) {
         System.out.println(name + "[" + k + "] = " + array[k]);
          
      }
   }
}

Output

It will print the following result.

UTF 8 Bytes[0] = -61
UTF 8 Bytes[1] = -122
UTF 8 Bytes[2] = -61
UTF 8 Bytes[3] = -104
UTF 8 Bytes[4] = -61
UTF 8 Bytes[5] = -123
Unicode Bytes[0] = -58
Unicode Bytes[1] = -40
Unicode Bytes[2] = -59

Java Internalization - Unicode Conversion from/to Reader/Writer

Reader and Writer classes are character oriented stream classes. These can be used to read and convert Unicode characters.

Conversion

Following example will showcase conversion of a Unicode String to UTF8 byte[] and UTF8 byte[] to Unicode byte[] using Reader and Writer classes.

IOTester.java

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.nio.charset.Charset;
import java.text.ParseException;

public class I18NTester {
   public static void main(String[] args) throws ParseException, IOException {

      String input = "This is a sample text" ;

      InputStream inputStream = new ByteArrayInputStream(input.getBytes());

      //get the UTF-8 data
      Reader reader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));

      //convert UTF-8 to Unicode
      int data = reader.read();
      while(data != -1){
         char theChar = (char) data;
         System.out.print(theChar);
         data = reader.read();
      }
      reader.close();

      System.out.println();

      //Convert Unicode to UTF-8 Bytes
      ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
      Writer writer = new OutputStreamWriter(outputStream, Charset.forName("UTF-8"));

      writer.write(input);
      writer.close();

      String out = new String(outputStream.toByteArray());
   
      System.out.println(out);
   }  
}

Output

It will print the following result.

This is a sample text
This is a sample text

Print