Reactive Everything: Completable, Single, and Maybe

So far, the Observable class has been our focus for enabling reactive programming with RxJava. However, RxJava also offers the following alternative base reactive types.

Single

In our previous example in Leaving the Reactive World, we looked at another base reactive type called a Single. As mentioned earlier, a Single is a special type of Observable that only emits a single item rather than a stream of items.