Java StringJoiner vs StringBuilder

StringJoiner

StringJointer was added to Java 8 in java.util package and is mostly used to add a delimiter between a sequence of Strings/Characters to join them.

Example of StringJoiner

package org.code2care.examples;

import java.util.StringJoiner;

public class StringJoinerExample1 {

    public static void main(String[] args) {
        StringJoiner stringJoiner = new StringJoiner(",");
        stringJoiner.add("1");
        stringJoiner.add("2");
        stringJoiner.add("3");
        stringJoiner.add("4");
        System.out.println(stringJoiner.toString());
    }
}

Output:
1,2,3,4

StringBuilder

StringBuilder is a legacy class available in Java since version 5 which is used to useful for dynamically constructing strings by appending, inserting, or modifying characters.

Example of StringBuilder

package org.code2care.examples;

public class StringBuilderExample {

    public static void main(String[] args) {
        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append("1");
        stringBuilder.append(",");
        stringBuilder.append("2");
        stringBuilder.append(",");
        stringBuilder.append("3");
        stringBuilder.append(",");
        stringBuilder.append("4");
        String result = stringBuilder.toString();
        System.out.println(result);
    }
}

Output:
1,2,3,4

StringJoiner vs StringBuilder

StringJoiner	StringBuilder
Join strings with a specific delimiter.	Build and manipulate strings efficiently.
Available since Java 8	Available since Java 5
StringJoiner are not mutable	StringBuilder are mutable.
Specified during initialization.	Appended using append method.
Join elements from a collection.	Dynamically build strings with append or insert operations.
Efficient for joining strings with a delimiter.	Efficient for dynamic string manipulations.
StringJoiner are Tread-Safe	StringBuilder are not Thread-Safe