Get the product of a list using java Lambdas

Question

How do you get the product of a array using java Lambdas. I know in C# it is like this:

result = array.Aggregate((a, b) => b * a);

edit: made the question more clear.

Answer 1

list.stream().reduce(1, (a, b) -> a * b);

Answer 2

You mention both arrays and lists, so here is how you would do it for both:

Integer intProduct = list.stream().reduce(1, (a, b) -> a * b);   
Integer intProduct = Arrays.stream(array).reduce(1, (a, b) -> a * b);  // Integer[]
int intProduct = Arrays.stream(array).reduce(1, (a, b) -> a * b);  // int[]

That version has one drawback if the list/array might be empty: the first argument, 1 in this case, will be returned as the result if the list or array are empty, so if you don't want that behavior, there is a version that will return an Optional<Integer> , OptionalInt, etc.:

Optional<Integer> intProduct = list.stream().reduce((a, b) -> a * b);   
Optional<Integer> intProduct = Arrays.stream(array).reduce((a, b) -> a * b);  // Integer[] 
OptionalInt intProduct = Arrays.stream(array).reduce((a, b) -> a * b);  // int[]