Tutorial: Using gettext in Java 5 (or later)

Since I'm a very big fan of gettext I also use gettext to create the resource bundles of my Java programs. Here is a short tutorial.
It's based on the gettext documentation.

Important notice: This tutorial doesn't make use of gted! It demostrates simply the functionality of GNU gettext with Java.

1. Create a class called Util

public class Util {

  private static ResourceBundle catalog = 
        ResourceBundle.getBundle("Messages");

  public static String _(String s) {
    return catalog.getString(s);
  }
}

2. Use Util as static import in your classes to mark the strings Translatable

import static Util._;

public class Translatable {

  public static void main(String[] args) {
    System.out.println(_("Text one"));
    System.out.println(_("Text two"));
  }
}

3. Generate .pot file from your Java sources

> xgettext -k_ -o po/messages.pot src/Translatable.java

-k_ indicates that the it must scan for calls to _()

4. Copy the .pot file to a .po file for the desired languages

Place the file under po/<languagecode>/messages.po

5. Generate ResourceBundles

> msgfmt --java2 -d resources -r Messages -l de po/de/messages.po

Hint: under Windows you have to set the TMPDIR: i.e. set TMPDIR=c:\temp

6. Run the program

Make sure that the folder resources is in the classpath!

The programs output should now be translated.

Appendix. Update .po files

To update your .po files run again:

> xgettext -k_ -o po/messages.pot src/Translatable.java

Then merge the new .pot file to the existing .po files

> msgmerge -U po/de/messages.po po/messages.pot