Java mapToInt vs Reduce with map

Question

I\'ve been reading up on reduce and have just found out that there is a 3 argument version that can essentially perform a map reduce like this:

String[] stra         


        

Answer 1

The three-argument Stream.reduce is more flexible:

 U reduce(U identity,
             BiFunction accumulator,
             BinaryOperator combiner);

in comparison with the two-argument IntStream.reduce that accepts and returns only int values:

int reduce(int identity, IntBinaryOperator op);

While accumulator in the three-argument version can accept parameters of two different types:

BiFunction acc = (i, str) -> i + str.length();

that allows you to omit additional map operation:

Arrays.stream(strs).reduce(0, (i, str) -> i + str.length(), Integer::sum)