Get the latest value of an Observable and emit it immeditely

Question

I\'m trying to get the latest value of a given Observable and get it to emit immediately once it\'s called. Given the code below as an example:

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Answer 1

In RxJava, subscriber.onXXX is called asynchronous.It means that if your Observable emit items in new thread, you can never get the last item before return, except you block the thread and wait for the item.But if the Observable emit item synchronously and you dont' change it's thread by subscribeOn and observOn, such as the code:

Observable.just(1,2,3).subscribe();

In this case, you can get the last item by doing like this:

Integer getLast(Observable o){
    final int[] ret = new int[1];
    Observable.last().subscribe(i -> ret[0] = i);
    return ret[0];
}

It's a bad idea doing like this.RxJava prefer you to do asynchronous work by it.