Reduction vs MapToInt to obtain sum in Streams API

Asked May 18 '19 at 13:57

Active May 18 '19 at 18:16

Viewed 181 times

Following streams produces the same result however there are two different ways to achieve this.

Person.stream().map(Person::getAge).reduce(Integer::sum).get();

Person.stream().mapToInt( Person::getAge).sum();

I want to know difference among two and which one is better.

edited May 18 '19 at 14:05

Stefan Zobel

asked May 18 '19 at 13:57

T-Bag

what is the data type of age field in Person class? – Ravindra Ranwala May 18 '19 at 13:59
Its int. or integer type .. – T-Bag May 18 '19 at 14:01
If that is an int the latter outperforms the former due to auto boxing and unboxing. – Ravindra Ranwala May 18 '19 at 14:06
Not sure, checked JDK code for both but unable to understand that is why came here to seek help – T-Bag May 18 '19 at 14:09
Do you want an explanatory answer? If so let me know so that I can elaborate my comment above. – Ravindra Ranwala May 18 '19 at 14:16
Yes, Please that would be great. – T-Bag May 18 '19 at 14:18
@Eugene - Completely agree with you, but Ravindra is saying he knows something – T-Bag May 18 '19 at 14:19

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