Working with Subjects

So far, we have been working with Observables, Subscriber, Observer, and Scheduler entities to create our RxJava functional processing lines. In this section, we will introduce the reader to a new kind of entity in the RxJava framework, the Subject. The Subject is a sort of adapter or bridge entity that acts as an Observable and Observer:

public abstract class      Subject<T,R>
                extends    Observable<R>
                implements Observer<T>

Since it can act as a Subscriber, it can subscribe to one or more Observables that emit Objects of the generic type T, and since it acts as an Observable, it can emit events of the generic type R and receive subscriptions from other Subscriber. Hence, it can emit events of the same type as received or emit a different type of event.

For example, the Subject<String, Integer> will receive events of type String and emit events of the type Integer.

The Subject could receive the events from the Observable...