Creating an Object from Optional<Object>

Question

So I've created a stream which comes from a List but I'm having some trouble converting it into a <ObjectType>, here's what I've tried:

ObjectType sco = getList().stream()
                          .filter(p -> p.getValue() == value)
                          .findFirst(); //also tried .orElse(null);

would anyone, please, be so kind as to suggest where I'm going wrong? (I apologize if this has been asked before but I couldn't find a discussion on this particular topic (or didn't know the proper terms to search for))

Thanks in advance!

well I tried it without findFirst() and that was my downfall... If you use .findFirst().orElse(null) like @Brian Angew suggests it works perfectly. — Hans
– Hans, Commented Mar 23, 2017 at 16:20

Brian Agnew · Accepted Answer · 2020-07-14 10:21:59Z

42

findFirst() gives you an Optional and you then have to decide what to do if it's not present. So findFirst().orElse(null) should give you the object or null if it's not present

You could just do a .get() on the Optional, but that could be regarded as poor practice since get() will throw an exception if Optional has no content. You should normally assert presence/absence of the Optional and decide what to do in each case (that's why it's there - so that you know something is truly optional and you have to determine what to do)

If you have an action you want to perform on object presence, and you don't want to do anything on absence, you can call .ifPresent() and provide a lambda as an argument. That will be called with the contained object, if present.

As of Java 9, a further solution would be to use Optional.ifPresentOrElse()

edited Jul 14, 2020 at 10:21

answered Mar 23, 2017 at 13:20

Brian Agnew

273k38 gold badges342 silver badges443 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Josh · Accepted Answer · 2017-03-23 13:21:58Z

3

I think you may be looking for findFirst().or Else(null). findFirst() will return an Optional - empty in the case of an empty steam.

Unless I misunderstood your comment. Have you tried this, or did you try orElse(null) without findFirst()?

answered Mar 23, 2017 at 13:21

Josh

2,1872 gold badges17 silver badges22 bronze badges

Collectives™ on Stack Overflow

Creating an Object from Optional<Object>

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related