How to Convert a List to Comma-Separated String in Java

Lists in Java are a collection of items that can be held in a single variable.

If this list is holding strings inside, you have the option to convert it to a comma-separated string.

In this post, we'll learn the two best ways to turn a string list into a comma-separated string in Java.

Using the join() method

The most straight-forward way to convert a string list to a comma-separated string is to use the join() method that exists on the String class.

Simply call the join() method on the list and pass in the separator you want to use.

	List<String> fruits = List.of("apple", "banana", "orange");

String fruitList = String.join(", ", fruits);

System.out.println(fruitList);

	apple, banana, orange

Using Java Streams

Another way you can convert a string list to a comma-separated string is to use the collect() method on the Stream class.

Basically the idea is to take the list and turn it into a stream, then join the stream using the separator you want.

	List<String> fruits = List.of("apple", "banana", "orange");

String fruitList = fruits.stream()
    .collect(Collectors.joining(", "));

System.out.println(fruitList);

	apple, banana, orange

And there you have it, your string list is now a comma-separated string!

Conclusion

In this post, we learned two different methods to convert a list of strings to a single comma-separated string.

Your options are to use the join() method or the collect() method on the Stream class.

Thanks for reading!

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