The StringJoiner class helps in formatting strings when there are multiple values and you want to present them with some delimiter and some pre and post suffixes.

The delimiter, pre and post suffixes can be defined as part of the constructor which will be applied as the toString() is invoked on the StringJoiner object.

import java.util.*;public class StringJoinerEx{   public static void main(String args[])   {      StringJoinerEx stringJoinerEx = new StringJoinerEx();      stringJoinerEx.proceed();   }      private void proceed()   {      //Here, the first argument is the delimiter of the StringJoiner when items are added to it,       //the second and third will be used as the prefix and suffix of the complete string formed      StringJoiner stringJoiner = new StringJoiner("|", "{", "}");      //The second and the third arguments are optional, but if present,  must be together      //Also, they can be different from each other         stringJoiner.add("C").add("C++").add("Java");            System.out.println("String formed using StringJoiner: " + stringJoiner.toString());   }}/*

Expected output:

[[email protected]]# java StringJoinerExString formed using StringJoiner: {C|C++|Java}*/