Joining a List<String> in Java with commas and "and"

Question

Given a list

List<String> l = new ArrayList<String>(); l.add("one"); l.add("two"); l.add("three"); 

I have a method

String join(List<String> messages) {         if (messages.isEmpty()) return "";         if (messages.size() == 1) return messages.get(0);         String message = "";         message = StringUtils.join(messages.subList(0, messages.size() -2), ", ");         message = message + (messages.size() > 2 ? ", " : "") + StringUtils.join(messages.subList(messages.size() -2, messages.size()), ", and ");         return message;     } 

which, for l, produces "one, two, and three". My question is, is there a standard (apache-commons) method that does the same?, eg

WhatEverUtils.join(l, ", ", ", and "); 

To clarify. My problem is not getting this method to work. It works just as I want it to, it's tested and all is well. My problem is that I could not find some apache-commons-like module which implements such functionality. Which surprises me, since I cannot be the first one to need this.

But then maybe everyone else has just done

StringUtils.join(l, ", ").replaceAll(lastCommaRegex, ", and"); 

Answer 1

In Java 8 you can use String.join() like following:

Collection<String> elements = ....; String result = String.join(", ", elements); 

Answer 2

With Java 8, you can use streams with joiners.

Collection<String> strings; ... String commaDelimited = strings.stream().collect(Collectors.joining(",")); // use strings.parallelStream() instead, if you think //   there are gains to be had by doing fork/join