CODEWITHSUNDEEP
javajava-8
Pikappa
Pikappa

Reputation: 284

Retrieving List<String> from List<Object> containing List<String> with java stream

I have this situation:

Class Employee{
//some attributes
List<String> idContract

//getter, setter
}

And I need to retrieve a List idContracts from a list using java 8 stream.

I was trying something like that: 

lst.stream().filter(o->!o.getLstDipFuoriSoglia().isEmpty())
      .map(ResultOdg::getLstDipFuoriSoglia)
      .collect(Collectors.toList());

but that, of course, returns a List< List < String >>, so how can I achieve that goal?

Thanks for your answers

Upvotes: 0

Views: 343

Answers (1)

Ryuzaki L
Ryuzaki L

Reputation: 40048

Just add flatMap operation for converting List to Stream

lst.stream().filter(o->!o.getLstDipFuoriSoglia().isEmpty)
            .map(ResultOdg::getLstDipFuoriSoglia)
            .flatMap(List::stream)
            .collect(Collectors.toList());

Or you can have one flatMap operation

lst.stream().filter(o->!o.getLstDipFuoriSoglia().isEmpty)
            .flatMap(list->list.getLstDipFuoriSoglia().stream())
            .collect(Collectors.toList());

Upvotes: 7

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