To close this chapter, we will cover some helpful operators that can assist in debugging as well as getting visibility into an Observable chain. These are the action or doOn operators.
These three operators: doOnNext(), doOnComplete(), and doOnError() are like putting a mini Observer right in the middle of the Observable chain.
The doOnNext() operator allows you to peek at each emission coming out of an operator and going into the next. This operator does not affect the operation or transform the emissions in any way. We just create a side-effect for each event that occurs at that point in the chain. For instance, we can perform an action with each string before it is mapped to its length. In this case, we will just print them by providing a Consumer<T> lambda:
import io.reactivex.Observable;
public class Launcher {
public static void main(String[] args) {
Observable.just("Alpha", "Beta", "Gamma", "Delta", "Epsilon...