Java 8 has added a new class called StringJoiner. This concatenates Strings using a delimiter as well as adds a prefix and suffix to the concatenated String. Performance-wise, it is similar to StringBuffer.append, but it has the added advantage that it automatically adds a delimiter, prefix and suffix.
The following code demonstrates how the StringJoiner class can be used to concatenate Strings:
This code creates a StringJoiner. It specifies that a comma symbol (,) should be used as the delimiter. It also specifies that the “{“should be used as the prefix and “}” should be used as the suffix. It then invokes the add method with some String values. So, this concatenates the specified Strings using the specified delimiter, prefix and suffix. So, this code prints the following output:
{red,blue,green}