JavaFX 2 and Internationalization

Question

I've just started writing my first JavaFX 2 application after learning the basics and would like to internationalize it.

I notice that in JavaFX 1.x, the scripting language allowed for very simple internationalization of strings. Are there any similar features in JavaFX 2?

Basically: what is the best practice for internationalizing a JavaFX 2 application?

Answer 1

The basic steps (among others) of a java app internationalizing, are Localelizing and resource bundling. In JavaFX, you can use FXMLLoader#setResources() for that purposes. Here a SSCCE demo to demonstrate it. The codes are self-descriptive.
Demo package structure:

bundledemo
    |------ BundleDemo.java
    |------ MyController.java
    |------ MyView.fxml  
bundles
    |------ MyBundle_en.properties
    |------ MyBundle_kg.properties

MyBundle_en.properties

key1=Name Surname
key2=How are you?

MyBundle_kg.properties

key1=Aты Жөнү
key2=Кандайсың?

MyView.fxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.layout.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.*?>

<BorderPane fx:controller="bundledemo.MyController" xmlns:fx="http://javafx.com/fxml">
    <top>
        <!-- This label's text will be set by the controller -->
        <Label fx:id="lblTextByController"/> 
    </top>
    <center>
        <!-- This label's text will be taken from the bundle automatically -->
        <Label text="%key2"/>
    </center>
</BorderPane>

MyController.java

package bundledemo;

import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;

public class MyController implements Initializable {

    @FXML private Label lblTextByController;
    private ResourceBundle bundle;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        bundle = resources;
        lblTextByController.setText(bundle.getString("key1"));
    }
}

BundleDemo.java

package bundledemo;
// imports are ignored.

public class BundleDemo extends Application {

    private Stage stage;

    @Override
    public void start(Stage primaryStage) {
        stage = primaryStage;
        Button btnEN = new Button();
        btnEN.setText("English");
        btnEN.setOnAction(new EventHandler<ActionEvent>() {
            @Override public void handle(ActionEvent event) {
                loadView(new Locale("en", "EN"));
            }
        });

        Button btnKG = new Button();
        btnKG.setText("Kyrgyz");
        btnKG.setOnAction(new EventHandler<ActionEvent>() {
            @Override public void handle(ActionEvent event) {
                loadView(new Locale("kg", "KG"));
            }
        });

        VBox root = new VBox(20);
        root.getChildren().add(HBoxBuilder.create().spacing(10).style("-fx-background-color: gray").padding(new Insets(5)).children(btnEN, btnKG).build());
        root.getChildren().add(new StackPane());
        primaryStage.setScene(new Scene(root, 300, 250));
        primaryStage.show();
    }

    private void loadView(Locale locale) {
        try {
            FXMLLoader fxmlLoader = new FXMLLoader();
            fxmlLoader.setResources(ResourceBundle.getBundle("bundles.MyBundle", locale));
            Pane pane = (BorderPane) fxmlLoader.load(this.getClass().getResource("MyView.fxml").openStream());
            // replace the content
            StackPane content = (StackPane) ((VBox) stage.getScene().getRoot()).getChildren().get(1);
            content.getChildren().clear();
            content.getChildren().add(pane);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    public static void main(String[] args) {
        launch(args);
    }
}

Screenshot:

Answer 2

This works for me:

└───src
    ├───app
    ├───bundles // <- here the "bundles"
    ├───dicts
    ├───images
    ├───libs
    └───resources

In the bundles package are

LangBundle_en.properties
LangBundle_de.properties

Sample content:

enter_pwd=Enter your password:

To load them I use the following code:

@Override
public void initialize(URL location, ResourceBundle resources) {
    ResourceBundle lngBndl = ResourceBundle
            .getBundle("bundles.LangBundle", new Locale("en", "EN"));

    tvSetupPwd.setText(lngBndl.getString("enter_pwd"));
    // ...
}

Answer 3

Look at my example

More I described here or on GitHub

Update:

the solution is in Messages.java

/**
 * The class with all messages of this application.
 */
public abstract class Messages {

    private static ResourceBundle BUNDLE;

    private static final String FIELD_NAME = "lookup";
    private static final String BUNDLE_NAME = "messages/messages";
    private static final String CONTROLS_BUNDLE_NAME = "com/sun/javafx/scene/control/skin/resources/controls";

    public static final String MAIN_APP_TITLE;

    public static final String DIALOG_HEADER;
    public static final String MAIN_CONTROLLER_CONTENT_TEXT;
    public static final String MAIN_CONTROLLER_HELLO_TEXT;
    public static final String MAIN_CONTROLLER_GOODBYE_TEXT;

    static {
        final Locale locale = Locale.getDefault();
        final ClassLoader classLoader = ControlResources.class.getClassLoader();

        final ResourceBundle controlBundle = getBundle(CONTROLS_BUNDLE_NAME,
                locale, classLoader, PropertyLoader.getInstance());

        final ResourceBundle overrideBundle = getBundle(CONTROLS_BUNDLE_NAME,
                PropertyLoader.getInstance());

        final Map override = getUnsafeFieldValue(overrideBundle, FIELD_NAME);
        final Map original = getUnsafeFieldValue(controlBundle, FIELD_NAME);

        //noinspection ConstantConditions,ConstantConditions,unchecked
        original.putAll(override);

        BUNDLE = getBundle(BUNDLE_NAME, PropertyLoader.getInstance());

        MAIN_APP_TITLE = BUNDLE.getString("MainApp.title");

        DIALOG_HEADER = BUNDLE.getString("Dialog.information.header");
        MAIN_CONTROLLER_CONTENT_TEXT = BUNDLE.getString("MainController.contentText");
        MAIN_CONTROLLER_HELLO_TEXT = BUNDLE.getString("MainController.helloText");
        MAIN_CONTROLLER_GOODBYE_TEXT = BUNDLE.getString("MainController.goodbyeText");
    }

    public static ResourceBundle GetBundle() {
        return BUNDLE;
    }
}

and in PropertyLoader.java

public class PropertyLoader extends ResourceBundle.Control {

    private static final String PROPERTIES_RESOURCE_NAME = "properties";

    private static final PropertyLoader INSTANCE = new PropertyLoader();

    public static PropertyLoader getInstance() {
        return INSTANCE;
    }

    @Override
    public ResourceBundle newBundle(final String baseName, final Locale locale, final String format,
                                    final ClassLoader loader, final boolean reload)
            throws IllegalAccessException, InstantiationException, IOException {

        final String bundleName = toBundleName(baseName, locale);
        final String resourceName = toResourceName(bundleName, PROPERTIES_RESOURCE_NAME);

        ResourceBundle bundle = null;
        InputStream stream = null;

        if (reload) {

            final URL url = loader.getResource(resourceName);

            if (url != null) {
                final URLConnection connection = url.openConnection();
                if (connection != null) {
                    connection.setUseCaches(false);
                    stream = connection.getInputStream();
                }
            }

        } else {
            stream = loader.getResourceAsStream(resourceName);
        }

        if (stream != null) {
            try {
                bundle = new PropertyResourceBundle(new InputStreamReader(stream, StandardCharsets.UTF_8));
            } finally {
                stream.close();
            }
        }

        return bundle;
    }
}