In this source code example, we show how to use Java 8 Collectors.joining() method with an example.

Java 8 Collectors.joining() example

In below example, we join list of strings using Java 8 Collectors.joining() method:

import java.util.List;
import java.util.ArrayList;
import java.util.stream.Collectors;

public class JavaCollectToListEx {

    public static void main(String[] args) {

        List < String > programmingLanguages = new ArrayList < > ();
        programmingLanguages.add("C");
        programmingLanguages.add("C++");
        programmingLanguages.add("Java");
        programmingLanguages.add("Kotlin");
        programmingLanguages.add("Python");
        programmingLanguages.add("Perl");
        programmingLanguages.add("Ruby");

        // filter all four character words into a list
        String joined = programmingLanguages.stream().collect(Collectors.joining(","));

        System.out.printf("Joined string: %s", joined);
    }
}

Output:

Joined string: C,C++,Java,Kotlin,Python,Perl,Ruby