You will likely have moments where you want to take a series of emissions and consolidate them into a single emission (usually emitted through a Single). We will cover a few operators that accomplish this. Note that nearly all of these operators only work on a finite Observable that calls onComplete() because typically, we can consolidate only finite datasets. We will explore this behavior as we cover these operators.
The simplest operator to consolidate emissions into a single one is count(). It will count the number of emissions and emit through a Single once onComplete() is called, shown as follows:
import io.reactivex.Observable;
public class Launcher {
public static void main(String[] args) {
Observable.just("Alpha", "Beta", "Gamma", "Delta", "Epsilon")
.count()
.subscribe(s -> System.out.println("Received: " + s));
}
}The output of the preceding code snippet is as follows:
Received: 5
Like most reduction operators...