What is the purpose of using Stream API in repositories?

Stream API in repositories is used for convenient and efficient processing of data collections obtained from a database or other sources. The essence is that instead of fetching and processing all data at once, you can apply a chain of intermediate operations (filtering, mapping, sorting) and terminal operations, which improves code readability and flexibility.

Advantages:

• Allows writing declarative code that is easier to maintain.
• Enables lazy data processing, saving resources.
• Convenient for combining operations without creating intermediate collections.

Example:

List<User> users = userRepository.findAll();
List<String> emails = users.stream()
    .filter(u -> u.isActive())
    .map(User::getEmail)
    .collect(Collectors.toList());

In repositories, Stream API helps build flexible queries and process results without unnecessary loops and temporary lists.