Title says. I want to scan a directory for language files i put into mod.

public class RoWLocalizer{

    public static final String localeFiles[] = {"/assets/row/lang/en_US.lang", "/assets/row/lang/de_DE.lang",
            "/assets/row/lang/ru_RU.lang"};

    public static void init(){
        // This actually works, but i don't want to list every language file in localeFiles[].
        /**
         * <pre>
         * for(String s: localeFiles){
         *     LanguageRegistry.instance().loadLocalization(s, getLocaleFromFileName(s), false);
         *     FMLCommonHandler.instance().getFMLLogger()
         *             .log(Level.INFO, "[RoW] Loaded language file " + getLocaleFromFileName(s));
         * }
         * </pre>
         **/
        // The code i'm trying to get to work.
        File localesLocation = new File("/assets/row/lang/");
        if(localesLocation.exists() && localesLocation.isDirectory()){
            for(File f: localesLocation.listFiles()){
                String s = f.getName();
                if(f.isFile() && s.endsWith(".lang")){
                    LanguageRegistry.instance().loadLocalization(s, getLocaleFromFileName(s), false);
                    FMLCommonHandler.instance().getFMLLogger()
                            .log(Level.INFO, "[RoW] Loaded language file " + getLocaleFromFileName(s));
                }
            }
        }else{
            FMLCommonHandler.instance().getFMLLogger()
                    .log(Level.INFO, "[RoW] Can't load lang files from " + localesLocation);
        }
    }

    public static String getLocaleFromFileName(String f){
        return f.substring(f.lastIndexOf('/') + 1, f.lastIndexOf('.'));
    }
}

For some reason i'm always having 'Can't load lang files from' message. Any ideas?

No need to do this.

Minecraft will automatically load languages from assets/MODID/lang/EXISTING_LANGUAGE.lang.

No, it does not.

Can you show me your en_US.lang file?