String.join() vs other string concatenation operations

Question

I have quickly read over the Java8 String api documentation.

Now I am little curious about String.join() method to concat/join strings.

This kind of example

Answer 1

We can use StringJoiner (Java8+)

import java.util.StringJoiner;

public class StringJoinerTest {

public static final String FILESEPARATOR = ", ";

public static void main(String[] args) {

    StringJoiner sj = new StringJoiner(FILESEPARATOR);
    sj.add("Test1");
    sj.add("Test2");
    sj.add("Test3");
    System.out.println(sj);
   }
}

Output is

Test1, Test2, Test3