Stream API in Java

Stream API in Java — a practical guide to Java Stream API with clear examples you can reuse in real projects.

Java Tutorial Series (63/90). Prefer one article? Read the complete Java tutorial.

Short description

Streams are not data structures — they process sequences of elements in a pipeline.

Stream pipeline

import java.util.List;

List<Integer> nums = List.of(1, 2, 3, 4, 5);
int sum = nums.stream()
    .filter(n -> n % 2 == 0)
    .mapToInt(n -> n)
    .sum();
System.out.println(sum);