Use ResourceBundle and properties files to add multilanguage support to your application

import java.util.Locale;
import java.util.Properties;
import java.util.ResourceBundle;
import java.io.FileOutputStream;
 
/**
 * Show how to use ResourceBundle and properties files to add multilanguage 
 * support to your application.
 * Note: You will get the following error message:
 * java.util.MissingResourceException Can't find bundle for base name, locale...
 * If the properties are not placed at the right place. Here are the solutions:
 * 
 * 1)
 * Copy all properties into the build folder(e.g. bin\ folder)
 * or
 * 2)
 * In eclipse, add the root folder of your project in Run Configurations->Classpath->User Entries.
 *  Click on the Advancesd... button.
 *  Select the Add Folders.
 *  Select the root folder of your project.
 *  Click on the OK button.
 * @author Xuan Ngo
 */
public class MultiLangualProperties
{
 
  public static void main(String[] args)
  {
    MultiLangualProperties oMp = new MultiLangualProperties();
    oMp.createProperties();
 
    // Load properties files.
    ResourceBundle oEnRBundle = ResourceBundle.getBundle("myproperties", Locale.ENGLISH);
    ResourceBundle oFrRBundle = ResourceBundle.getBundle("myproperties", Locale.FRENCH);
 
    String s = String.format("French equivalent of '%s' is '%s'.", oEnRBundle.getString("dog"), oFrRBundle.getString("dog"));
    System.out.println(s); // The output: French equivalent of 'dog' is 'chien'.
  }
  /**
   * Create all properties files.
   */
  public void createProperties()
  {
    this.createBaseProperty();
    this.createFrenchProperty();
  }
 
  /**
   * Create base properties file.
   */
  public void createBaseProperty()
  {
    // Create the properties object and add some values.
    Properties oWriteProperties = new Properties();
    oWriteProperties.setProperty("dog", "dog");
 
    // Save properties into file. 
    try
    {
      oWriteProperties.store(new FileOutputStream("myproperties.properties"), "Base properties");
    }
    catch(Exception ex)
    {
      System.out.println(ex.getMessage());
    }
  }
 
  /**
   * Create french properties file.
   */
  public void createFrenchProperty()
  {
    // Create the properties object and add some values.
    Properties oWriteProperties = new Properties();
    oWriteProperties.setProperty("dog", "chien");
 
    // Save properties into file. 
    try
    {
      oWriteProperties.store(new FileOutputStream("myproperties_fr.properties"), "French properties");
    }
    catch(Exception ex)
    {
      System.out.println(ex.getMessage());
    }
  }    
}

Troubleshooting reference: http://javahowto.blogspot.com/2006/05/debug-java-util-missingresourceexcepti.html