Java How to Program, Early Objects, 11th Edition

• ... the elements that are divisible by 2 (that is, the even integers), producing a stream of the even integers from 2, 4, 6, 8 and 10.

• Line 12 maps each element (x) in the stream to that element times 3, producing a stream of the even integers from 6, 12, 18, 24 and 30.

• Line 13 reduces the stream to the sum of its elements (90).

The new feature here is the filtering operation in line 11. IntStream method filter receives as its argument a method that takes one parameter and returns a boolean result. If the result is true for a given element, that element is included in the resulting stream.

The lambda in line 11:

x -> x % 2 == 0

determines whether its int argument is divisible by 2 (that is, the remainder after dividing by 2 is 0) and, if so, returns ...