rx

Class Subscriber<T>

java.lang.Object

rx.Subscriber<T>

Type Parameters:

T - the type of items the Subscriber expects to observe

All Implemented Interfaces:

Observer<T>, Subscription

Direct Known Subclasses:

SafeSubscriber, SerializedSubscriber, TestSubscriber

public abstract class Subscriber<T>
extends java.lang.Object
implements Observer<T>, Subscription

Provides a mechanism for receiving push-based notifications from Observables, and permits manual unsubscribing from these Observables.

After a Subscriber calls an Observable's subscribe method, the Observable calls the Subscriber's Observer.onNext(T) method to emit items. A well-behaved Observable will call a Subscriber's Observer.onCompleted() method exactly once or the Subscriber's Observer.onError(java.lang.Throwable) method exactly once.

See Also:

ReactiveX documentation: Observable

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Subscriber()
protected	Subscriber(Subscriber<?> subscriber) Construct a Subscriber by using another Subscriber for backpressure and for holding the subscription list (when this.add(sub) is called this will in fact call subscriber.add(sub)).
protected	Subscriber(Subscriber<?> subscriber, boolean shareSubscriptions) Construct a Subscriber by using another Subscriber for backpressure and optionally for holding the subscription list (if shareSubscriptions is true then when this.add(sub) is called this will in fact call subscriber.add(sub)).

Method Summary

Modifier and Type	Method and Description
void	add(Subscription s) Adds a Subscription to this Subscriber's list of subscriptions if this list is not marked as unsubscribed.
boolean	isUnsubscribed() Indicates whether this Subscriber has unsubscribed from its list of subscriptions.
void	onStart() This method is invoked when the Subscriber and Observable have been connected but the Observable has not yet begun to emit items or send notifications to the Subscriber.
protected void	request(long n) Request a certain maximum number of emitted items from the Observable this Subscriber is subscribed to.
void	setProducer(Producer p) If other subscriber is set (by calling constructor Subscriber(Subscriber) or Subscriber(Subscriber, boolean)) then this method calls setProducer on the other subscriber.
void	unsubscribe() Stops the receipt of notifications on the Subscriber that was registered when this Subscription was received.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface rx.Observer

onCompleted, onError, onNext

Constructor Detail

Subscriber

protected Subscriber()

Subscriber

protected Subscriber(Subscriber<?> subscriber)

Construct a Subscriber by using another Subscriber for backpressure and for holding the subscription list (when this.add(sub) is called this will in fact call subscriber.add(sub)).

Parameters:

subscriber - the other Subscriber

Subscriber

protected Subscriber(Subscriber<?> subscriber,
                     boolean shareSubscriptions)

Construct a Subscriber by using another Subscriber for backpressure and optionally for holding the subscription list (if shareSubscriptions is true then when this.add(sub) is called this will in fact call subscriber.add(sub)).

To retain the chaining of subscribers when setting shareSubscriptions to false, add the created instance to subscriber via add(rx.Subscription).

Parameters:

subscriber - the other Subscriber

shareSubscriptions - true to share the subscription list in subscriber with this instance

Since:

1.0.6

Method Detail

add

public final void add(Subscription s)

Adds a Subscription to this Subscriber's list of subscriptions if this list is not marked as unsubscribed. If the list is marked as unsubscribed, add will indicate this by explicitly unsubscribing the new Subscription as well.

Parameters:

s - the Subscription to add

unsubscribe

public final void unsubscribe()

Description copied from interface: Subscription

Stops the receipt of notifications on the Subscriber that was registered when this Subscription was received.

This allows deregistering an Subscriber before it has finished receiving all events (i.e. before onCompleted is called).

Specified by:

unsubscribe in interface Subscription

isUnsubscribed

public final boolean isUnsubscribed()

Indicates whether this Subscriber has unsubscribed from its list of subscriptions.

Specified by:

isUnsubscribed in interface Subscription

Returns:

true if this Subscriber has unsubscribed from its subscriptions, false otherwise

onStart

public void onStart()

This method is invoked when the Subscriber and Observable have been connected but the Observable has not yet begun to emit items or send notifications to the Subscriber. Override this method to add any useful initialization to your subscription, for instance to initiate backpressure.

request

protected final void request(long n)

Request a certain maximum number of emitted items from the Observable this Subscriber is subscribed to. This is a way of requesting backpressure. To disable backpressure, pass Long.MAX_VALUE to this method.

Requests are additive but if a sequence of requests totals more than Long.MAX_VALUE then Long.MAX_VALUE requests will be actioned and the extras may be ignored. Arriving at Long.MAX_VALUE by addition of requests cannot be assumed to disable backpressure. For example, the code below may result in Long.MAX_VALUE requests being actioned only.

 request(100);
 request(Long.MAX_VALUE-1);
 

Parameters:

n - the maximum number of items you want the Observable to emit to the Subscriber at this time, or Long.MAX_VALUE if you want the Observable to emit items at its own pace

Throws:

java.lang.IllegalArgumentException - if n is negative

setProducer

public void setProducer(Producer p)

If other subscriber is set (by calling constructor Subscriber(Subscriber) or Subscriber(Subscriber, boolean)) then this method calls setProducer on the other subscriber. If the other subscriber is not set and no requests have been made to this subscriber then p.request(Long.MAX_VALUE) is called. If the other subscriber is not set and some requests have been made to this subscriber then p.request(n) is called where n is the accumulated requests to this subscriber.

Parameters:

p - producer to be used by this subscriber or the other subscriber (or recursively its other subscriber) to make requests from