RxJava: combine two optional observables
问题 I have two Observable s, let's call them PeanutButter and Jelly . I'd like to combine them to a Sandwich Observable . I can do that using: Observable<PeanutButter> peanutButterObservable = ...; Observable<Jelly> jellyObservable = ...; Observable<Sandwich> sandwichObservable = Observable.combineLatest( peanutButterObservable, jellyObservable, (pb, j) -> makeSandwich(pb, j)) The problem is that RX waits for the first PeanutButter and the first Jelly to be emitted before emitting the first