# The Stream.reduce Method

//The following pipeline uses the Stream.reduce operation to calculate the sum
//of the male members' ages in the collection roster:

Integer totalAgeReduce = roster
.stream()
.map(Person::getAge)
.reduce(
0,
(a, b) -> a + b);
• The Stream.reduce method is a general-purpose reduction operation.
• The reduce operation may take two arguments: identity and accumulator.
• The reduce operation always returns a new value.

## Related concepts

The Stream.reduce Method

## The Stream.reduce Method — Structure map

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