StringJoiner setEmptyValue() method in Java

The setEmptyValue(CharSequence emptyValue) of StringJoiner sets the sequence of characters to be used when determining the string representation of this StringJoiner and no elements have been added yet, that is, when it is empty. A copy of the emptyValue parameter is made for this purpose. Note that once an add method has been called, the StringJoiner is no longer considered empty, even if the element(s) added correspond to the empty String. Syntax:

public StringJoiner setEmptyValue(CharSequence emptyValue)

Parameters: This method accepts a mandatory parameter emptyValue which is the characters to return as the value of an empty StringJoiner Returns: This method returns this StringJoiner itself, so the calls may be chained Exception: This method throws NullPointerException when the emptyValue parameter is null Below examples illustrates the setEmptyValue() method: Example 1: 

Initial StringJoiner: 
After setEmptyValue(): StrigJoiner is empty
Final StringJoiner: Geeks forGeeks

Example 2: To demonstrate NullPointerException 

Initial StringJoiner: 
Exception when adding null in setEmptyValue(): 
 java.lang.NullPointerException: 
 The empty value must not be null

Time complexity: O(1).

Auxiliary Space: O(1).