How to Sum a LongStream in Java 8

By Yashwant Chavan, Views 1081, Last updated on 09-Nov-2016

This tutorial will help to learn how to use LongStream to do the sum a Long values in Java 8. rangeClosed() method returns a sequential ordered LongStream elements base on start inclusive and end inclusive.

tags java

Refer below steps.

  • LongStream.rangeClosed(long start, long end) - returns a sequential ordered LongStream from start to end (inclusive) by an incremental step of 1. Start inclusive is 1 and end inclusive is 5.
  • LongStream.reduce(LongBinaryOperator op) - performs a reduction on the elements of this stream, using an associative accumulation function and return the OptionalLong.
  • Long::sum - Define LongBinaryOperator operator, which will return sum of elements.
  • Get the value from OptionalLong.

Sum of LongStream elements

package com.technicalkeeda.app;

import java.util.stream.LongStream;

public class SumLongStream {
    public static void main(String[] args) {
        long sum = LongStream.rangeClosed(1, 5).reduce(Long::sum).getAsLong();
        System.out.println("sum:- " + sum);
    }
}

output

sum:- 15
Yashwant

Yashwant

Hi there! I am founder of technicalkeeda.com and programming enthusiast. My skills includes Java,J2EE, Spring Framework, Nodejs, PHP and lot more. If you have any idea that you would want me to develop? Lets connect: yashwantchavan[at][gmail.com]