5. Java 8: Parallel Stream

Question 1

Given a Collection how can one make a parallel stream?

Answer 1

Collection.parallelStream();

Question 2

Given a Stream how can one transform it into a parallel stream and back to a regular stream again.

Answer 2

stream.parallel()

.sequential();

Question 3

How can you use the reduce function of a Stream to sum all the integers of this Integer stream?

Answer 3

Stream stream = Stream.of(1, 2, 3);

Integer sum = stream.reduce(0, Integer::sum);