Learning RxJava

toList()

A common collection operator is toList(). For a given Observable<T>, it will collect incoming emissions into a List<T> and then push that entire List<T> as a single emission (through Single<List<T>>). In the following code snippet, we collect string emissions into a List<String>. After the preceding Observable signals onComplete(), that list is pushed forward to the observer to be printed:

import io.reactivex.Observable;public class Launcher {      public static void main(String[] args) {        Observable.just("Alpha", "Beta", "Gamma", "Delta", "Epsilon")          .toList()          .subscribe(s -> System.out.println("Received: " + s));      }}

The output of the preceding code snippet is as follows:

    Received: [Alpha, Beta, Gamma, Delta, Epsilon]

By default, toList() ...