# reduce()

A stream operation that combines elements into one result.

## What does **reduce()** do in Java?

**reduce()** — A stream operation that combines elements into one result.

```java
import java.util.List;

class NumberTotal {
    int total(List<Integer> numbers) {
        return numbers.stream()
                .reduce(0, Integer::sum);
    }
}
```

Level: Freelancer · [More Java terms at this level](https://www.ask-codey.com/glossary/subjects/java/freelancer)

Updated: September 27, 2026

## In other subjects

- [reduce() in JavaScript](https://www.ask-codey.com/glossary/reduce-javascript)

Source: https://www.ask-codey.com/glossary/reduce