What are streams (Stream API) used for?

The Stream API in Java is designed for convenient and efficient processing of data collections in a functional style. The main goals and advantages of streams:

• Allow writing declarative code for operations on collections (filtering, transforming, sorting, etc.).
• Support lazy computations — operations are performed only when necessary.
• Simplify parallel data processing using parallel streams.
• Improve readability and reduce the amount of code.

Example of using the Stream API:

List<String> names = Arrays.asList("Anna", "Bob", "Charlie", "David");

List<String> filtered = names.stream()
    .filter(name -> name.startsWith("A"))
    .map(String::toUpperCase)
    .collect(Collectors.toList());

System.out.println(filtered); // [ANNA]

Thus, the Stream API is a powerful tool for data processing that makes code more expressive and efficient.