IntStream reduce(int identity, IntBinaryOperator op) performs a reduction on the elements of this stream, using the provided identity value and an associative accumulation function, and returns the reduced value.
A reduction operation or fold takes a sequence of input elements and combines them into a single summary result, such as finding the sum or maximum of a set of numbers. An operator or function op is associative if the following holds :
(a op b) op c == a op (b op c)
This is a terminal operation i.e, it may traverse the stream to produce a result or a side-effect. After the terminal operation is performed, the stream pipeline is considered consumed, and can no longer be used.
Syntax :
int reduce(int identity, IntBinaryOperator op)
Parameters :
- identity : The identity value for the accumulating function.
- IntBinaryOperator : An operation upon two int-valued operands and producing an int-valued result.
- op : An associative, stateless function for combining two values.
Return Value : The result of the reduction.
Example 1 :
// Java code for IntStream reduce// (int identity, IntBinaryOperator op)import java.util.*;import java.util.stream.IntStream;  class GFG {      // Driver code    public static void main(String[] args)    {        // Creating an IntStream        IntStream stream = IntStream.of(2, 3, 4, 5, 6);          // Using IntStream reduce        // (int identity, IntBinaryOperator op)        int answer = stream.reduce(0, (num1, num2)                                          -> (num1 + num2) * 2);          // Displaying the result        System.out.println(answer);    }} |
Output :
176
Example 2 :
// Java code for IntStream reduce// (int identity, IntBinaryOperator op)import java.util.*;import java.util.stream.IntStream;  class GFG {      // Driver code    public static void main(String[] args)    {        // Creating an IntStream        IntStream stream = IntStream.range(4, 10);          // Using IntStream reduce        // (int identity, IntBinaryOperator op)        int answer = stream.reduce(0, (num1, num2)                                          -> (num1 + num2) - 2 * (num1 - num2));          // Displaying the result        System.out.println(answer);    }} |
Output :
9
