Java: convert List<String> to a join()d String

To convert a List<String> to a single string by joining the elements of the list with a separator, you can use the join() method of the java.util.StringJoiner class.

Here's an example of how you can use the StringJoiner class to join the elements of a List<String>:

import java.util.List;
import java.util.StringJoiner;

List<String> list = List.of("apple", "banana", "cherry");

StringJoiner joiner = new StringJoiner(", ");
for (String s : list) {
  joiner.add(s);
}
String joined = joiner.toString();

System.out.println(joined); // apple, banana, cherry

Alternatively, you can use the Collectors.joining() method of the java.util.stream.Collectors class to join the elements of a List<String> using a stream:

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

List<String> list = List.of("apple", "banana", "cherry");

String joined = list.stream().collect(Collectors.joining(", "));

System.out.println(joined); // apple, banana, cherry

Both of these examples will produce a string that contains the elements of the List<String> separated by a comma and a space.