In Java how do I find out what languages I have available my Resource Bundle

Question

I have some resource bundles packaged in my main jar

widget_en.properties widget_de.properties 

I retrieve a resource bundle based on my default locale as folows

ResourceBundle.getBundle("widget", Locale.getDefault()); 

But I want to present the user with a list of available languages supported so that can select a language that may be different to their computers default

But I can't find a method in ResourceBundle that would list available locales, I don't want to hardcode a list as I may forget to update it when another resource bundle is added.

EDIT

As I only resource bundles for different language (I dont have country refinements) so I have got generated a list by iterating through all the known language codes and check for each one as a resource.

String[]langs = Locale.getISOLanguages(); for(String lang:langs) {       URL rb = ClassLoader.getSystemResource("widget_"+lang+".properties");       if(rb!=null)       {             System.out.println("Found:"+rb.toString());       } } 

Answer 1

If you really package the resource files inside your JAR, then I would do it like this:

public static void main(String[] args) {   Set<ResourceBundle> resourceBundles = getResourceBundles(A.class.getName());   if (resourceBundles.isEmpty())     // ... }  public static Set<ResourceBundle> getResourceBundles(String baseName) {   Set<ResourceBundle> resourceBundles = new HashSet<>();    for (Locale locale : Locale.getAvailableLocales()) {     try {       resourceBundles.add(ResourceBundle.getBundle(baseName, locale));     } catch (MissingResourceException ex) {       // ...     }   }    return Collections.unmodifiableSet(resourceBundles); } 

If you care about your JARs then you would at least get a set containing the default resource for a given baseName.

If you have only resources with names like baseName_<country> this method works perfectly, because only those ResourceBundles will be added to the set which are present in your JAR. It'll work even if you decide you need separate baseName_en_US and baseName_en_UK resources, which is not unheard of.

_{Shameless self-plug: I wrote a ResourceBundle.Control which takes a Charset as its argument, you might be interested in it if you want to load UTF-8 encoded resources files. It's available at GitHub.}