Fastest way to put contents of Set to a single String with words separated by a whitespace?

Question

I have a few Sets and want to transform each of these into a single String where each element of the original Set is sep

Answer 1

If you are using Java 8, you can use the native

String.join(CharSequence delimiter, Iterable elements)

method:

Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter. For example:

 Set strings = new LinkedHashSet<>();
 strings.add("Java"); strings.add("is");
 strings.add("very"); strings.add("cool");
 String message = String.join("-", strings);
 //message returned is: "Java-is-very-cool"

Set implements Iterable, so simply use:

String.join(" ", set_1);