LongStream sum() returns the sum of elements in this stream. This is a special case of a reduction. LongStream sum() is a terminal operation i.e, it may traverse the stream to produce a result or a side-effect.
Note : A reduction operation (also called a fold) takes a sequence of input elements and combines them into a single summary result by repeated application of a combining operation, such as finding the sum or maximum of a set of numbers.
Syntax :
long sum()
Return Value : The function returns the sum of elements in this stream.
Example 1 :
Java
// Java code for LongStream.sum() to// find the sum of elements in LongStreamimport java.util.*;import java.util.stream.LongStream;class GFG { // Driver code public static void main(String[] args) { // Creating an LongStream LongStream stream = LongStream.of(2L, 4L, 6L, -2L, -4L); // Using LongStream.sum() to find // sum of elements in LongStream long sumOfElements = stream.sum(); // Displaying the calculated sum System.out.println(sumOfElements); }} |
Output:
6
Example 2 :
Java
// Java code for LongStream.sum() to// find the sum of elements// divisible by 3 in given rangeimport java.util.*;import java.util.stream.LongStream;class GFG { // Driver code public static void main(String[] args) { // Using LongStream.sum() to find // sum of elements divisible by 3 // in given range long sumOfElements = LongStream.range(2L, 10L) .filter(num -> num % 3 == 0) .sum(); // Displaying the calculated sum System.out.println(sumOfElements); }} |
Output:
18
