Join array elements with a separator in Java

Question

Is there a way to join an array, i.e. perform opposite operation of what split() does. Iterating through an array requires either adding a condition (if this is not the last element, add the separator) or using substring to remove the last separator. 

I'm sure there is a certified, efficient way to do it but not able to find it. Please suggest.

Answer 1

Using Java 8, you can easily perform the required function:

String.join(delimiter, elements);

This can work in 3 ways:

• Directly specifying the elements

String arr1 = String.join(",", "a", "b", "c");

• Using arrays

String[] arr = new String[] { "a", "b", "c" };
String arr2 = String.join(",", array);

• Using iterables

List<String> list = Arrays.asList(array);
String arr3= String.join(",", list);