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Load resources via a resources fileTag(s): Internationalization


With the previous JAVA How-to, the resources were stored in classes. The drawback is when there is a modification, we must recompile the class. With a resources file, we simply add or modify the resource in a special file with a regular text editor. The JDK provides a class, PropertyResourceBundle, to use properties file very easily. In fact, from the programmer's point of view, there is no difference if the resources are stored in classes or properties files.

The ResourceBundle will look first for classes and if not found, it will look for properties files. We don't have to specify filenames, the ResourceBundle will construct the filename using the same mechanism used for classes. The file must have the extension .properties.

The ResourceBundle try to load the properties file from the current classpath.

If the properties are stored in subdirectory , use "." instead of "/".

For example, let's say that the properties file is in a subdirectory called "subdir" (from the current directory). Then you can load the ResourcesDynamic resources file with 

ResourceBundle.getBundle("subdir.ResourcesDynamic", localeCurrent);
[InternationalDynamic.java] 
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("res.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);
  }
}
[RresourcesDynamic.properties] 
title=Example
r0=United States
r1=France
r2=Germany
rDefault=r0
btnQuit=Quit
today=(def) {0,date,long}
[RresourcesDynamic_en.properties] 
title=Example
r0=United States
r1=France
r2=Germany
rDefault=r0
btnQuit=Quit
today=(en) {0,date,long}
[ResourcesDynamic_fr.properties] 
title=Exemple
r0=Etats-Unis
r1=France
r2=Allemagne
rDefault=r1
btnQuit=Quitte
today=(fr) {0,date, dd/MM/yyyy}
[ResourcesDynamic_de.properties] 
title=Beispiel
r0=Vereinigte Staaten
r1=Frankreich
r2=Deutschland
rDefault=r2
btnQuit=Verlassen
today=(de) {0,date,dd.MM.yyyy}