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Load resources dynamicallyTag(s): Internationalization


This HowTo lets you select a language and change its GUI to reflect the choice.

We are using a special class, a ListResourceBundle, to store our resources. We have a class per Locale. If a specific resource is not in a specific Locale ListResourceBundle then the default resource is used.

To use a properties file instead of a class to store resources then look at this HowTo.

[InternationalDynamic.java (main program)] 

import java.util.*;
import java.text.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class InternationalDynamic extends JFrame
    implements ActionListener
{

  static Locale[] localesSupported = {
     Locale.US, Locale.FRANCE, Locale.GERMANY
  };

  int localeChoosen = 0;
  Locale localeCurrent;
  ResourceBundle rb;

  ButtonGroup bg;
  JButton btnQuit;
  JRadioButton r0, r1, r2;
  JLabel today;
  boolean defaultDone = false;

  public void initLocale(){
    localeCurrent = localesSupported[localeChoosen];
    this.setLocale(localeCurrent);
    rb = ResourceBundle.getBundle("ResourcesDynamic", localeCurrent);
  }

  public void initText() {
    setTitle (rb.getString("title"));
    r0.setText(rb.getString("r0"));
    r1.setText(rb.getString("r1"));
    r2.setText(rb.getString("r2"));
    btnQuit.setText(rb.getString("btnQuit"));
    Date d = new Date();
        MessageFormat mf = new MessageFormat
           (rb.getString("today"), localeCurrent);
    today.setText(mf.format(new Object [] { d }));
  }

  public void initGUI(){
    setLayout(new FlowLayout());

    // RADIO buttons
    bg = new ButtonGroup();
    r0 = new JRadioButton();
    r1 = new JRadioButton();
    r2 = new JRadioButton();
    bg.add(r0);
    bg.add(r1);
    bg.add(r2);
    add(r0);
    add(r1);
    add(r2);

    // default RADIO button
    if (!defaultDone) {
       String rDef =  rb.getString("rDefault");
       if (rDef.equals("r0"))
           r0.setSelected(true);
       else if (rDef.equals("r1"))
           r1.setSelected(true);
       else
           r2.setSelected(true);
       defaultDone = true;
    }
    else {
       if (localeChoosen == 0)
           r0.setSelected(true);
       else if (localeChoosen == 1)
           r1.setSelected(true);
       else
           r2.setSelected(true);
    }

    // QUIT button
    btnQuit = new JButton();
    add(btnQuit);

    // today label
    today = new JLabel();
    add(today);

    //
    r0.addActionListener(this);
    r1.addActionListener(this);
    r2.addActionListener(this);
    btnQuit.addActionListener(this);

    setSize(400,100);
    setVisible(true);
  }

  public void actionPerformed(ActionEvent ae){
    if (ae.getSource() == btnQuit) {
       System.exit(0);
    }
    else if (ae.getSource() == r0) localeChoosen = 0;
    else if (ae.getSource() == r1) localeChoosen = 1;
    else if (ae.getSource() == r2) localeChoosen = 2;
    initLocale();
    initText();
    pack();
  }

  public static void main(String args[]) {
      System.out.println("Current Locale : " + Locale.getDefault());
      Thread t = new Thread () {
        public void run() {
            InternationalDynamic i = new InternationalDynamic();
            i.initLocale();
            i.initGUI();
            i.initText();
            i.pack();
        }
      };
      SwingUtilities.invokeLater(t);
  }
}
[ResourcesDynamic.java (default resources)] 
import java.util.*;

public class ResourcesDynamic extends ListResourceBundle {
  public Object [][] getContents() {
    return contents;
  }

  static final Object[][] contents =   {
    { "title", "Example" },
    { "r0" , "United States" } ,
    { "r1", "France" } ,
    { "r2"  , "Germany"},
    { "rDefault"  , "r0" },
    { "btnQuit"  , "Quit"},
    { "today"  , " (def) {0,date,long}"},
  };
}
[ResourcesDynamic_en.java (english language resources)] 
import java.util.*;

public class ResourcesDynamic_en extends ListResourceBundle {
  public Object [][] getContents() {
     return contents;
     }

   static final Object[][] contents =  {
      { "title", "Example" },
      { "r0" , "United States" } ,
      { "r1", "France" } ,
      { "r2"  , "Germany"},
      { "rDefault"  , "r0" },
      { "btnQuit"  , "Quit"},
      { "today"  , " (en) {0,date,long}"},
     };
}
[ResourcesDynamic_fr.java (french language resources)] 
import java.util.*;

public class ResourcesDynamic_fr extends ListResourceBundle {
  public Object [][] getContents() {
     return contents;
  }

  static final Object[][] contents =   {
     { "title", "Exemple" },
     { "r0" , "Etats-Unis" } ,
     { "r1", "France" } ,
     { "r2", "Allemagne" },
     { "rDefault", "r1" },
     { "btnQuit", "Quitter" },
     { "today"  , " (fr) {0,date, dd/MM/yyyy}"},
  };
}
[ResourcesDynamic_de.java (german language resources)] 
import java.util.*;

public class ResourcesDynamic_de extends ListResourceBundle {
  public Object [][] getContents() {
    return contents;
  }
  static final Object[][] contents =  {
     { "title", "Beispiel" },
     { "r0" , "Vereinigte Staaten" } ,
     { "r1", "Frankreich" } ,
     { "r2", "Deutschland" },
     { "rDefault", "r2" },
     { "btnQuit", "verlassen"},
     { "today"  , " (de) {0,date,dd.MM.yyyy}"},
  };
}