Eliminate extra isPresent() call from Optional produced by Java Stream

Question

I'm a relatively novice Stream user and I feel like there should be a cleaner way to accomplish what I have below. Is it possible to accomplish what the code below does all within a single Stream (eliminating the if/else at the bottom)?

Thanks!

Optional<SomeMapping> mapping = allMappings.stream()
     .filter(m -> category.toUpperCase().trim().equalsIgnoreCase(m.getCategory().toUpperCase().trim()))
     .findAny();         
if (mapping.isPresent()) {
     return mapping.get();
} else {
     throw new SomeException("No mapping found for category \"" + category + "\.");
}

score 5 · Accepted Answer · edited Feb 12 '20 at 15:55

5

Use orElseThrow to throw an exception if the Optional is empty:

return
    allMappings.stream()
               .filter(m -> category.trim().equalsIgnoreCase(m.getCategory().trim()))
               .findAny()
               .orElseThrow(() -> new SomeException("No mapping found for category \"" + category + "\"."));

edited Feb 12 '20 at 15:55

Holger

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answered Feb 12 '20 at 15:01

Eran

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Ah, perfect! I was close, but couldn't quite get the syntax correct. Thanks!! – WishIWasJeeping Feb 12 '20 at 16:26

score 1 · Answer 2 · answered Feb 12 '20 at 15:11

1

No need to use toUpperCase() as you are comparing with equalsIgnoreCase().

return allMappings.stream().filter(m -> category.trim().equalsIgnoreCase(m.getCategory().trim()))
                       .findAny()
                       .orElseThorw (() -> new SomeException("No mapping found for category \"" + category + "\."));

answered Feb 12 '20 at 15:11

Ullas Sharma

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Now that there is [an edit](https://stackoverflow.com/revisions/60191230/4) on the other answer and otherwise as well the suggestion that you're making should be a comment and not an answer. – Naman Feb 12 '20 at 16:17
Derp, thanks for pointing that out! – WishIWasJeeping Feb 12 '20 at 16:27

Eliminate extra isPresent() call from Optional produced by Java Stream

2 Answers2