Java StringJoiner

StringJoiner Constructors

• StringJoiner(CharSequence delimiter) : It creates a StringJoiner with a duplicate of the supplied delimiter and no characters, prefixes, or suffixes.

public StringJoiner(CharSequence delimiter)




NullPointerException Exception Thrown if the delimiter is null







• StringJoiner(CharSequence delimiter, CharSequence prefix, CharSequence suffix) : It creates a StringJoiner devoid of characters by duplicating the supplied prefix, delimiter, and suffix. It will return the prefix + suffix (or properties thereof) in the result if no characters are added to the StringJoiner and methods accessing the string value are called, unless setEmptyValue has been called first.

public StringJoiner(CharSequence delimiter, CharSequence prefix, CharSequence suffix)




NullPointerException Exception Thrown if prefix, delimiter, or suffix is null.

Methods of StringJoiner Class

A Java program that displays the StringJoiner class's methods

import java.util.StringJoiner;

public class Main {
    public static void main(String[] args) {
        // Creating a StringJoiner object with delimiter ","
        StringJoiner sj1 = new StringJoiner(",");

        // Using setEmptyValue() method to set default value for empty StringJoiner object
        sj1.setEmptyValue("sj1 is empty");
        System.out.println(sj1); // sj1 is empty

        // Using add() method to add elements to StringJoiner object
        sj1.add("Ram").add("Jyoti").add("Alice").add("Shyam");
        System.out.println(sj1); // Ram,Jyoti,Alice,Shyam

        // Using length() method to get length of the StringJoiner object
        System.out.println("Length of sj1 : " + sj1.length()); // Length of sj1 : 17

        // Creating a new StringJoiner object with delimiter ":"
        StringJoiner sj2 = new StringJoiner(":");
        sj2.add("John").add("Jani").add("Jimmy");

        // Using merge() method to merge two StringJoiner objects
        sj1.merge(sj2);

        // Using toString() method to get the String representation of the StringJoiner object
        System.out.println(sj1.toString()); // Ram,Jyoti,Alice,Shyam,John:Jani:Jimmy

        // Using length() method to get length of the new StringJoiner object after merging
        System.out.println("Length of new sj1 : " + sj1.length()); // Length of new sj1 : 26
    }
}

This program creates two StringJoiner objects, adds elements to them using the add() method, sets a default value for the first object using setEmptyValue(), merges the two objects using the merge() method, and finally, gets the String representation of the merged object using the toString() method and gets its length using the length() method.

sj1 is empty
Ram,Shyam,Alice,Bob
Length of sj1 : 17
Ram,Shyam,Alice,Bob,John:Jane:Jim
Length of new sj1 : 26