Reactive Extensions

Observables

Observable.of(1, 2, 3)
    .subscribe(
        l => console.log(l),
        noop,
        () => console.log('Completed')
    );

Observable.just(1, 2, 3)
    .doOnComplete(() -> System.out.println("Completed"))
    .subscribe(System.out::println);

Output:

Completed

Cold observables

Cold

const textSubject = new Subject<string>();
textSubject.subscribe(
    l => console.log(l),
    noop,
    () => console.log('Completed')
);
textSubject.next('foo');
textSubject.next('bar');

Subject<String> textSubject = PublishSubject.create();
textSubject
        .doOnComplete(() -> System.out.println("Completed"))
        .subscribe(System.out::println);
textSubject.onNext("foo");
textSubject.onNext("bar");

Output:

foo

bar

Hot observables

No Completed??

const textSubject = new Subject<string>();
textSubject.subscribe(
    l => console.log(l),
    noop,
    () => console.log('Completed')
);
textSubject.complete();

Subject<String> textSubject = PublishSubject.create();
textSubject
        .doOnComplete(() -> System.out.println("Completed"))
        .subscribe(System.out::println);
textSubject.onComplete();

Output:

Completed

Complete Hot observables

Subjects are closed!

Terminates after N amount of values
Fixed amount of values
Ends after error OR complete

Terminates manually by calling onCompleted
Stays open for input
Ends after error OR complete

Cold vs hot

Subscriptions

const textSubject = new Subject<string>();
const subscription = textSubject
    .delay(100)
    .subscribe(
        l => console.log(l),
        noop,
        () => console.log('Completed')
    );
textSubject.next('foo');
subscription.unsubscribe();

Subject<String> textSubject = PublishSubject.create();
Disposable disposable = textSubject
        .doOnComplete(() -> System.out.println("Completed"))
        .delay(100, TimeUnit.MILLISECONDS)
        .subscribe(System.out::println);
textSubject.onNext("foo");
disposable.dispose();

Output:

Subscription/Disposable

Subscriptions are closed!

Cancel the stream action
Prevent memory leaks
Closes after error OR complete
Does not affect the actual stream

Subscriptions

RxDocs