CODEWITHSUNDEEP
rx-javarx-java2
Alex Kokorin
Alex Kokorin

Reputation: 469

How can I combine if-else statement in one return in reactive programming?

I've got a piece of following code:

.flatMap(sth -> {
  obj = sth.getSomeLast();
  if (obj.someField == null) {
    return dao.loadInfo(obj.id).map(info -> Entry(1, 2, info));
  } else {
    return Single.just(Entry(1, 2, null));
  }
})
.doOnNext(entry -> writer(entry));

How can I avoid using 2 returns (inside of if/else)? I was thinking about .filter and then defaultIfEmpty()

Upvotes: 0

Views: 2226

Answers (1)

Yudovin Artsiom
Yudovin Artsiom

Reputation: 109

you can use filter and defaultIfEmpty

Observable.just("one", "two")
             .filter(s -> !s.equals("a"))
             .map(s -> s + "!")
             .defaultIfEmpty(load());

But I don't recommend you to call any method in defaultIfMethod() because method load() will be called not depending on result of filter()

That's why you can use

.switchIfEmpty(Observable.fromCallable(() -> load()))

swithIfEmpty will work like lazy style, but defaultIfEmpty has in parameters some objects and so It'll work like eager style

Upvotes: 3

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