We encourage every developer to make their code localizable. The NLS class (based on the Eclipse RCP NLS idea) has been developed to aid in doing so.

Instead of hard-coding messages (UI strings), the NLS class allows us to put all a package’s messages into a ResourceBundle called messages. This ResourceBundle is a collection of files called messages.properties, messages_de.properties, messages_fr.properties, etc. The messages.properties file contains the English localization, messages_de.properties contains the German localization, and so on. The appropriate messages (depending on the system locale and the user.language property) are loaded into the fields of a Messages class which we can then use in the UI code.

Creating a localization

To localize Phoebus to your language you need to find every messages.properties file in the project and create a translated version called messages_xx.properties where xx is the appropriate locale code (fr, de, es, etc.). You should also add your locale to the POM as described in the next section.

Checking the completeness of localizations

To ease the maintenance of localizations, a report can be generated to quickly find missing or extra messages compared to the default English localization.

In order to do so, you must first make sure that the locale you’re interested in is listed in the configuration/locales section of the l10n-status Maven profile. In the following example, the report will include the German, Spanish and French localizations.

<!-- pom.xml (parent) -->

After that, you only need to run

mvn site -P l10n-status

The report will be located at target/site/l10n-status.html.

Writing localizable code

Suppose we want to be able to localize the following class:

package org.phoebus.mypackage;

public class MyClass
    public void greet()
        System.out.println("How are you today?");

The first step is to create a Messages.java file with the following boilerplate:

package org.phoebus.ui.mypackage;

import org.phoebus.framework.nls.NLS;

public class Messages
    public static String Hello;
    public static String HowAreYou;

        // initialize resource bundle

    private Messages()
        // Prevent instantiation.

Then, we replace the hard-coded strings in MyClass with Messages’s fields:

package org.phoebus.mypackage;

import org.phoebus.mypackage.Messages;

public class MyClass
    public void greet()

Finally, we create the messages ResourceBundle with all the localizations we want.


HowAreYou=How are you doing today?


HowAreYou=¿Cómo estás hoy?