How to throw exception from java streams after satisfying a filter condition

Question

I have list of response from a rest WS. This list contains "Response" objects in which each object contains e field called "tokenExpiry". If any one of these token expiry is < currentTimeInMillis , then I have to throw an exception

Pseudo code something like this

list.stream().filter(response -> response.tokenExpiry < currentTimeInMillis)

then throw new Exception.

@GhostCat Not a duplicate; an XY. – chrylis -cautiouslyoptimistic- Aug 02 '19 at 05:23 — chrylis -cautiouslyoptimistic-, Aug 02 '19 at 05:23

Ryuzaki L · Answer 1 · 2019-08-02T05:43:34.637

2

Use filter for Responses response.tokenExpiry<currentTimeInMillis and findFirst to break stream after first match, then use ifPresent to throw exception

list.stream().filter(response->response.tokenExpiry<currentTimeInMillis).findFirst().ifPresent(s-> {
        throw new RuntimeException(s);
    });

Or you can also use anyMatch which returns boolean

boolean res = list.stream().anyMatch(response->response.tokenExpiry<currentTimeInMillis)
if(res) {
    throw new RuntimeException();
 }

Or simple forEach is also better choice

list.forEach(response-> {
     if(response.tokenExpiry<currentTimeInMillis) {
           throw new RuntimeException();
      }
   });

edited Aug 02 '19 at 05:43

answered Aug 02 '19 at 05:02

Ryuzaki L

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Don't forget about `anyMatch()`. – chrylis -cautiouslyoptimistic- Aug 02 '19 at 05:23
anyMatch will return boolean right not an Optional @chrylis – Ryuzaki L Aug 02 '19 at 05:24
Correct, but if you don't need the matching element, you can eliminate the fluff. I'll make a note of the differences in our answers. – chrylis -cautiouslyoptimistic- Aug 02 '19 at 05:25
Also, `findAny` is nearly always good enough and sometimes more efficient. – chrylis -cautiouslyoptimistic- Aug 02 '19 at 05:26

score 1 · Answer 2 · answered Aug 02 '19 at 05:24

Java Streams have a specific method for checking whether any element of the stream matches a condition:

if (list.stream().anyMatch(r -> r.tokenExpiry < currentTimeInMillis)) {
    // throw your exception
}

This is a bit simpler and more efficient, but it doesn't provide you the actual value, which @Deadpool's find version does.

score 0 · Answer 3 · answered Aug 02 '19 at 05:55

0

Here's one way:

if(list.stream().filter(response -> (response.tokenExpiry<currentTimeInMillis).findAny().isPresent()) {
    throw new CustomExeption("message");
}

answered Aug 02 '19 at 05:55

Prashant Pandey

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How to throw exception from java streams after satisfying a filter condition

3 Answers3