question: private static List < String > calculateBundleNames ( String baseName , Locale locale ) { final List < String > result = new ArrayList < String > ( 3 ) ; final String language = locale . getLanguage ( ) ; final int languageLength = language . length ( ) ; final String country = locale . getCountry ( ) ; final int countryLength = country . length ( ) ; final String variant = locale . getVariant ( ) ; final int variantLength = variant . length ( ) ; result . add ( 0 , baseName ) ; if ( languageLength + countryLength + variantLength == 0 ) { return result ; } final StringBuilder temp = new StringBuilder ( baseName ) ; temp . append ( '_' ) ; temp . append ( language ) ; if ( languageLength > 0 ) { result . add ( 0 , temp . toString ( ) ) ; } if ( countryLength + variantLength == 0 ) { return result ; } temp . append ( '_' ) ; temp . append ( country ) ; if ( countryLength > 0 ) { result . add ( 0 , temp . toString ( ) ) ; } if ( variantLength == 0 ) { return result ; } temp . append ( '_' ) ; temp . append ( variant ) ; result . add ( 0 , temp . toString ( ) ) ; return result ; }
target:  Copied from java.util.ResourceBundle implementation