Java Streams

What is a Stream?

Introduced in Java 8, a Stream is a sequence of elements that supports functional-style operations — filtering, mapping, and reducing — without modifying the original data source.

Example

List<Integer> evens = numbers.stream()
    .filter(n -> n % 2 == 0)
    .collect(Collectors.toList());

Why Testers Use Streams

Streams make it concise to filter or transform data extracted from a response — for example, pulling out all "active" user IDs from a list of user objects returned by an API.