Joining a List in Java with commas and “and”

Question

Given a list

List l = new ArrayList();
l.add(\"one\");
l.add(\"two\");
l.add(\"three\");

I have a method

<

Answer 1

What about join from: org.apache.commons.lang.StringUtils

Example:

StringUtils.join(new String[] { "one", "two", "three" }, ", "); // one, two, three

To have "and" or ", and" you can simple replace the last comma.

Answer 2

Other answers talk about "replacing the last comma", which isn't safe in case the last term itself contains a comma.

Rather than use a library, you can just use one (albeit long) line of JDK code:

public static String join(List<String> msgs) {
    return msgs == null || msgs.size() == 0 ? "" : msgs.size() == 1 ? msgs.get(0) : msgs.subList(0, msgs.size() - 1).toString().replaceAll("^.|.$", "") + " and " + msgs.get(msgs.size() - 1);
}

See a live demo of this code handling all edge cases.

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FYI, here's a more readable two-liner:

public static String join(List<String> msgs) {
    int size = msgs == null ? 0 : msgs.size();
    return size == 0 ? "" : size == 1 ? msgs.get(0) : msgs.subList(0, --size).toString().replaceAll("^.|.$", "") + " and " + msgs.get(size);
}