Additional brackets in Java8 stream map() function

Question

I\'m working/testing streams in Java8 and come across very frustrating issue. I\'ve got the code which compiles well:

        List words = Arra         


        

Answer 1

Your lambda expression returns a value. If you use brackets you need to add a return statement to your lambda function:

List words = Arrays.asList("Oracle", "Java", "Magazine");
List wordLengths = words.stream().map((x) -> {
    return x.toUpperCase();
}).collect(Collectors.toList());