In Java streams is peek really only for debugging?

Question

I\'m reading up about Java streams and discovering new things as I go along. One of the new things I found was the peek() function. Almost everything I\'ve read

Answer 1

Although I agree with most answers above, I have one case in which using peek actually seems like the cleanest way to go.

Similar to your use case, suppose you want to filter only on active accounts and then perform a login on these accounts.

accounts.stream()
    .filter(Account::isActive)
    .peek(login)
    .collect(Collectors.toList());

Peek is helpful to avoid the redundant call while not having to iterate the collection twice:

accounts.stream()
    .filter(Account::isActive)
    .map(account -> {
        account.login();
        return account;
    })
    .collect(Collectors.toList());