Sum of the lengths of a string array using Java 8 streams

Question

I've written this code that doesn't compile:

String[] text = {"hello", "bye"};
IntStream.of(Arrays.stream(text).map(String::length)).sum()

Do I need to convert the stream to an IntStream? And why do I get an error when I pass String::length to the map() function?

Answer 1

You should use Stream.mapToInt in order to get an IntStream instance:

String[] text = {"hello", "bye"};
int total = Arrays.stream(text).mapToInt(String::length).sum();

Answer 2

Try this

Arrays.stream(text)
      .filter(Objects::nonNull)
      .mapToInt(String::length)
      .reduce(0,Integer::sum);