I'm looking for a quick and easy way to do exactly the opposite of split
so that it will cause ["a","b","c"] to become "a,b,c"
Iterating through an array requires either adding a condition (if this is not the last element, add the seperator) or using substring to remove the last separator.
I'm sure there is a certified, efficient way to do it (Apache Commons?)
How do you prefer doing it in your projects?
I prefer Guava over Apache StringUtils for this particular problem:
Joiner.on(separator).join(array)
Compared to StringUtils, the Joiner API has a fluent design and is a bit more flexible, e.g. null elements may be skipped or replaced by a placeholder. Also, Joiner has a feature for joining maps with a separator between key and value.
Apache Commons Lang does indeed have a StringUtils.join method which will connect String arrays together with a specified separator.
For example:
String[] s = new String[] {"a", "b", "c"};
String joined = StringUtils.join(s, ","); // "a,b,c"
However, I suspect that, as you mention, there must be some kind of conditional or substring processing in the actual implementation of the above mentioned method.
If I were to perform the String joining and didn't have any other reasons to use Commons Lang, I would probably roll my own to reduce the number of dependencies to external libraries.
"I'm sure there is a certified, efficient way to do it (Apache Commons?)"
yes, apparenty it's
StringUtils.join(array, separator)