Comments on: Code idiom: inserting a separator between the elements in a list

By: Simon Brunning

Simon Brunning — Thu, 29 Apr 2004 11:21:48 +0000

Nice - but don’t reinvent the wheel: http://jakarta.apache.org/commons/lang/api/org/apache/commons/lang/StringUtils.html#join(java.util.Iterator, java.lang.String)

Hmmm, funny URL with a space in it.

By: Joel Hockey

Joel Hockey — Tue, 11 Mar 2003 04:42:55 +0000

Nice. I often use the following idiom as well:



StringBuffer sb = new StringBuffer();

List l = …;

String sep = ",";

for (Iterator i = l.iterator(); i.hasNext(); ) {

    String s = (String) i.next();

    sb.append(s).append(sep);

}
return out.substring(0, sb.length() - sep.length());

I like it because it is a little more explicit, but without any conditional processing within a loop.

By: Ivan

Ivan — Tue, 25 Feb 2003 00:07:34 +0000

I’ve used this same fellow as far back as I can remember, but I always felt dirty about:
a) Wasted effort appending a blank string for the first iteration.
b) Subsequent redundant assignments to the sep variable.

Sure, I feel bad, but it’s still my hammer for every nail.

By: Jason

Jason — Sat, 22 Feb 2003 15:11:51 +0000

Very elegant.

By: Philippe

Philippe — Sat, 22 Feb 2003 09:19:36 +0000

Totally agreed… a programmer on my team did it last week when he wrote the utility function to convert collections to such strings and vice-versa… I was pleasently surprised :)

By: Bruce

Bruce — Fri, 21 Feb 2003 14:14:12 +0000

Can this be done by ‘Separation of Concerns’

By: Bill

Bill — Fri, 21 Feb 2003 07:20:17 +0000

Agreed, great tip.

By: Oliver

Oliver — Fri, 21 Feb 2003 06:01:32 +0000

Sweet - I really like that tip.