Calling method after Optional.filter() without passing in object

Question

I can understand the below:

user
  .filter(u -> "Sam".equals(u.getName()))
  .ifPresent(this::doSomethingWithUser);

if user.getName is equal to "Sam" then pass user to local method doSomethingWithUser().

However, what if I simply wanted to call a local method, without passing user but keeping the check that user.getName is equal to "Sam"?

Does this use case make using Optional redundant?

score 4 · Accepted Answer · answered Nov 06 '19 at 12:44

4

Just ignore the mandatory function parameter. This means you cannot use shorthand :: syntax and goes like this:

user
  .filter(u -> "Sam".equals(u.getName()))
  .ifPresent(u -> doSomethingWithoutUser());

answered Nov 06 '19 at 12:44

drekbour

1

Interesting question... I've posted it here: https://stackoverflow.com/questions/58734350/is-adapting-a-no-arg-method-into-a-consumer-bad-form – drekbour Nov 06 '19 at 16:14
Sure, to fix the incorrect comment. I meant converting a *`Consumer` into a `Runnable`*. Not sure how effective or good of a practice is it!! – Naman Nov 06 '19 at 16:32

score 1 · Answer 2 · answered Nov 06 '19 at 12:20

1

You can just check for the presence of the Optional for such case:

if(user.filter(u -> "Sam".equals(u.getName()).isPresent()) {
    // call your method without user
}

answered Nov 06 '19 at 12:20

Naman

2 Answers2