DoubleStream reduce(DoubleBinaryOperator op) in Java
DoubleStream reduce(DoubleBinaryOperator op) performs a reduction on the elements of this stream, using an associative accumulation function, and returns an OptionalDouble describing the reduced value, if any.
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.
OptionalDouble reduce(DoubleBinaryOperator op)
- OptionalDouble : A container object which may or may not contain a long value. If a value is present, isPresent() will return true and getAsDouble() will return the value.
- DoubleBinaryOperator : An operation upon two double-valued operands and producing a double-valued result.
- op : An associative, stateless function for combining two values.
Return Value : An OptionalDouble describing the reduced value, if any.
Example 1 :
Example 2 :