What is the equivalent of Regex-replace-with-function-evaluation in Java 7?

Question

I\'m looking for a very simple way of getting the equivalent of something like the following JavaScript code. That is, for each match I would like to call a certain

Answer 1

Since Java 9 Matcher.replaceAll:

Pattern.compile("\\S+").matcher("Hello World!")
        .replaceAll(mr -> "" + mr.group().length());

The parameter freely named mr is a MatchResult, with access methods like mr.group(1) or mr.end() - mr.start().