Let's look at the signature of the method first:
public final static <T> Observable<T> create(OnSubscribe<T>)
It takes a parameter of type
OnSubscribe. This interface extends the
Action1<Subscriber<? super T>> interface; in other words, this type has only one method, taking one argument of type
Subscriber<T> and returning nothing. This function will be called every time the
Observable.subscribe() method is invoked. Its argument, an instance of the
Subscriber class, is in fact the observer, subscribing to the
Observable instance (here, the
Subscriber class and Observer interface have the same role). We'll be talking about them later in this chapter). We can invoke the
onCompleted() methods on it, implementing our own custom behavior.
<T> Observable<T> fromIterable...