RxJava2使用Flowable检测零事件条件

Question

I am using an android library FrangSierra for listening to Firebase database events. This library returns RxJava2 Flowables to work with. I show a loading dialog when I start loading data and need to hide it when data is received. Now the problem is when there is no data and I need to show an empty view because Flowable never calls OnComplete .

I tried applying timeout and the problem is it will probably always timeout after data is finished loading. I also want to keep subscription for future events. My question is how do I detect 0 records scenario here.

Answer 1

You can use switchIfEmpty operator:

Flowable.just(1)
        .filter(value -> (value != 1))
        .switchIfEmpty(Completable.fromRunnable(() -> System.out.println("Empty stream")).toFlowable())
        .subscribe();