StringJoiner add() method in Java

The add(CharSequence newElement) of StringJoiner adds a copy of the given CharSequence value as the next element of the StringJoiner value. If newElement is null, then "null" is added.
Syntax: 

public StringJoiner add(CharSequence newElement)

Parameters: This method takes a mandatory parameter newElement which is the element to be added.
Returns: This method returns a reference to this StringJoiner
Below programs illustrate the add() method:
Example 1: To demonstrate add() with delimiter " " 

Geeks for Geeks

Example 2: To demonstrate add() with delimiter ","