public static String lookupTag (List<LanguageRange> priorityList, Collection<String> tags)

Returns the best-matching language tag using the lookup mechanism defined in RFC 4647.

priorityList    user's Language Priority List in which each language tag is sorted in descending order based on priority or weight
tags    language tangs used for matching

Returns:  the best matching language tag chosen based on priority or weight, or null if nothing matches.

NullPointerException    if priorityList or tags is null

Since:  1.8