Internationalization (I18N)

• The process of designing a web application such that it supports various countries, various languages without performing any changes in the application is called Internationalization.

• If the request is coming from India then the response should be in India specific form , and if the request is from US then the response should be in US specific form.

• We can implement Internationalization by using the following classes.

• They are:

• 1. Locale
• 2. NumberFormat 
• 3. DateFormat

1. Locale

• A Locale object can be used to represent a geographic (country) location (or) language.

• Locale class present in java.util package.

• It is a final class and direct child class of Object and , implements Cloneable, andSerializable Interfaces.

How to create a Locale object:

• We can create a Locale object by using the following constructors of Locale class.

• Locale l=new Locale(String language);
• Locale l=new Locale(String language,String country); 

• Locale class already defines some predefined Locale constants. We can use these constants directly.

Example:

   Locale. UK
   Locale. US
   Locale. ITALY
   Locale. CHINA

Important methods of Locale class:

• 1. public static Locale getDefault()

• 2. public static void setDefault(Locale l)

• 3. public String getLanguage()

• 4. public String getDisplayLanguage(Locale l)

• 5. public String getCountry()

• 6. public String getDisplayCountry(Locale l)

• 7. public static String[] getISOLanguages()

• 8. public static String[] getISOCountries()

• 9. public static Locale[] getAvailableLocales()

Example for Locale:

import java.util.*;
class LocaleDemo{
   public static void main(String args[]){
      Locale l1=Locale.getDefault();
     //System.out.println(l1.getCountry()+"....."
     +l1.getLanguage());
     
       //System.out.println(l1.getDisplayCountry()+"....."
     +l1.getDisplayLanguage());
      
      Locale l2=new Locale("pa","IN");
      Locale.setDefault(l2);
      String[] s3=Locale.getISOLanguages();
      for(String s4:s3) {
             //System.out.print("ISO language is :");
             //System.out.println(s4);
      }
      String[] s4=Locale.getISOCountries();
      for(String s5:s4) {
         System.out.print("ISO Country is:");
         System.out.println(s5);
      }
      Locale[] s=Locale.getAvailableLocales();
      for(Locale s1:s) {
        //System.out.print("Available locales is:");                        
        //System.out.println(s1.getDisplayCountry()+"......
          "+s1.getDis playLanguage());
      }
   }
}

2. NumberFormat

• Various countries follow various styles to represent number.

Example:

double d=123456.789;
1,23,456.789------------INDIA
123,456.789-------------US
123.456,789-------------ITALY

• By using NumberFormat class we can format a number according to a particular Locale.

• NumberFormat class present in java.Text package and it is an abstract class. Hence we can't create an object by using  constructor.

• NumberFormat nf=new NumberFormat(); --------invalid

Getting NumberFormat object for the default Locale:

• NumberFormat class defines the following methods for this.
• 
  
  
  
  

• Getting NumberFormat object for the specific Locale:

• The methods are exactly same but we have to pass the corresponding Locale object as argument.

• Example: 
• public static NumberFormatgetNumberInstance(Locale l);

• Once we got NumberFormat object we can call the following methods to format and parse numbers.

•    public String format(long l);
•    public String format(double d);

• To convert a number from java form to Locale specific form. 
• public Number parse(String source)throws ParseException

• To convert from Locale specific String form to java specific form.
• 
  
  

Requirement: 

• Write a program to display java number form into Italy specific form.

Example:

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

class NumberFormatDemo {
 public static void main(String args[]){
   double d=123456.789;
   NumberFormat nf=NumberFormat.getInstance(Locale.ITALY); 
   System.out.println("ITALY form is :"+nf.format(d));

 }
}

Output:

   ITALY form is :123.456,789

Requirement: 

• Write a program to print a java number in INDIA, UK, US and ITALY currencyformats.

Program:

import java.util.*;
import java.text.*;
class NumberFormatDemo {
   public static void main(String args[]){
      double d=123456.789;
      Locale INDIA=new Locale("pa","IN");
      
      NumberFormat nf=NumberFormat.getCurrencyInstance(INDIA);
      System.out.println("INDIA notation is :"+nf.format(d));
      
      NumberFormat nf1=NumberFormat.getCurrencyInstance(Locale.UK);
      System.out.println("UK notation is :"+nf1.format(d));

      NumberFormat nf2=NumberFormat.getCurrencyInstance(Locale.US);
      System.out.println("US notation is :"+nf2.format(d));

      NumberFormat nf3=NumberFormat.getCurrencyInstance(Locale.ITALY);
      System.out.println("ITALY notation is :"+nf3.format(d));
   }
}

Output:

   INDIA notation is: INR 123,456.79
   UK notation is: ú123,456.79
   US notation is: $123,456.79
   ITALY notation is: Ç 123.456,79

Setting Maximum, Minimum, Fraction and Integer digits:

• NumberFormat class defines the following methods for this purpose.

• 1. public void setMaximumFractionDigits(int n);
• 2. public void setMinimumFractionDigits(int n);
• 3. public void setMaximumIntegerDigits(int n);
• 4. public void setMinimumIntegerDigits(int n);

Example:

import java.text.*;
public class NumberFormatExample {
   public static void main(String[] args){
      NumberFormat nf=NumberFormat.getInstance();
      nf.setMaximumFractionDigits(3);
      System.out.println(nf.format(123.4));
      
      System.out.println(nf.format(123.4567));
      nf.setMinimumFractionDigits(3);
      System.out.println(nf.format(123.4));
      
      System.out.println(nf.format(123.4567));
      nf.setMaximumIntegerDigits(3);
      System.out.println(nf.format(1.234));
      
      System.out.println(nf.format(123456.789));
      nf.setMinimumIntegerDigits(3);
      System.out.println(nf.format(1.234));
      
      System.out.println(nf.format(123456.789));
   }
}

Output:

   123.4
   123.457
   123.400
   123.457
   1.234
   456.789
   001.234
   456.789

3. DateFormat:

• Various countries follow various styles to represent Date. We can format the date according to a particular locale by using DateFormat class.

• DateFormat class present in java.text package and it is an abstract class.

Getting DateFormat object for default Locale:

• DateFormat class defines the following methods for this purpose.
•  
  
  
  
• The dafault style is Medium style

Getting DateFormat object for the specific Locale:

• public static DateFormat getDateInstance(int style, Locale l);

• Once we got DateFormat object we can format and parse Date by using the following methods.

• public String format(Date date); 
• To convert the date from java form to locale specific string form.

• public Date parse(String source)throws ParseException -
• To convert the date from locale specific form to java form.

• 
  
  

Requirement: 

• Write a program to represent current system date in all possible styles of us format.

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• Date and time

Program:

import java.text.*;
import java.util.*;
public class DateFormatDemo {
   public static void main(String args[]){ 
      System.out.println("full form is 
         :"+DateFormat.getDateInstance(0).format(new Date())); 
      System.out.println("long form is 
         :"+DateFormat.getDateInstance(1).format(new Date())); 
      System.out.println("medium form is 
         :"+DateFormat.getDateInstance(2).format(new Date())); 
      System.out.println("short form is 
         :"+DateFormat.getDateInstance(3).format(new Date())); }
}

Output:

   Full form is: Wednesday, July 20, 2011
   Long form is: July 20, 2011
   Medium form is: Jul 20, 2011
   Short form is: 7/20/11

Requirement: 

• Write a program to represent current system date in UK, US and ITALY styles.

Program:

import java.text.*;
import java.util.*;
public class DateFormatDemo {
   public static void main(String args[]){
      DateFormat UK=DateFormat.getDateInstance(0,Locale.UK); 
      DateFormat US=DateFormat.getDateInstance(0,Locale.US); 
      DateFormat ITALY=DateFormat.getDateInstance(0,Locale.ITALY); 
      
      System.out.println("UK style is :"+UK.format(new Date())); 
      System.out.println("US style is :"+US.format(new Date())); 
      System.out.println("ITALY style is :"+ITALY.format(new Date()));
   }
}

Output:

   UK style is: Wednesday, 20 July 2011
   US style is: Wednesday, July 20, 2011
   ITALY style is: mercoled 20 luglio 2011

Getting DateFormat object to get both date and time:

• DateFormat class defines the following methods for this.
• 
  
  

Example:

import java.text.*;
import java.util.*;
public class DateFormatDemo {
   public static void main(String args[]){
      DateFormat ITALY=
         DateFormat.getDateTimeInstance(0,0,Locale.ITALY); 
      System.out.println("ITALY style is:
         "+ITALY.format(new Date()));
   }
}

Output:

   ITALY style is: mercoled 20 luglio 2011 23.21.30 IST