Why can't I use Apache's StringUtils.join on a List?

Question

When I try

StringUtils.join(myList,',');

I get a compilation failure:

cannot find symbol
symbol  : method join(java.util.List,char)

But the following works:

StringUtils.join(myList.toArray(),',');

The docs (Apache Commons Lang 2.5) seem to indicate that both should work, as they record both:

public static String join(Collection collection,
                      char separator)

and

public static String join(Object[] array,
                      char separator)

Any ideas? For the record, I'm importing import org.apache.commons.lang.StringUtils;

It's available since version 2.3. Do you have an outdated JAR file? — home, Aug 23 '11 at 17:18
I actually have the same problem but i've checked everything and my versions 2.6 — Kevin, Aug 24 '11 at 16:24
@Kevin My issue was the version of apache-commons in my project. If you are having the same symptoms with version 2.6, you may want to ask your own question. (This question, with an accepted answer, is not likely to receive more attention.) — Eric Wilson, Aug 24 '11 at 16:39

score 12 · Accepted Answer · answered Aug 23 '11 at 17:17

12

The most probable reason is, that you are using an older version of Commons Lang, since the method using a Collection has only been added in 2.3.

You can check that by looking in the MANIFEST.MF file in the Jar at the Implementation-Version field.

answered Aug 23 '11 at 17:17

nfechner

score 2 · Answer 2 · edited Jan 25 '12 at 04:44

2

I had the problem earlier and realized it is due to the order of my import.

Once I shifted my commons JAR up the order of import, it works.

Hope this helps.

edited Jan 25 '12 at 04:44

Brock Adams

answered Jan 24 '12 at 09:22

Phoebe Chan

score 0 · Answer 3 · answered Aug 28 '13 at 19:35

Not quite your problem but related:

In org.apache.commons.lang.StringUtils, there exists a method

join(Object[])

That doesn't take a delimiter.

join(Object[], char)
join(Collection, char)

All take delimiters (may use String instesad of char). So if you forget the delimiter, your error message may be pointing to the wrong problem.

3 Answers3