io.reactivex.rxjava3.observers

Class ResourceObserver<T>

java.lang.Object

io.reactivex.rxjava3.observers.ResourceObserver<T>

Type Parameters:

T - the value type

All Implemented Interfaces:

Observer<T>, Disposable

public abstract class ResourceObserver<T>
extends Object
implements Observer<T>, Disposable

An abstract Observer that allows asynchronous cancellation of its subscription and associated resources.

All pre-implemented final methods are thread-safe.

To release the associated resources, one has to call dispose() in onError() and onComplete() explicitly.

Use add(Disposable) to associate resources (as Disposables) with this ResourceObserver that will be cleaned up when dispose() is called. Removing previously associated resources is not possible but one can create a CompositeDisposable, associate it with this ResourceObserver and then add/remove resources to/from the CompositeDisposable freely.

Use the dispose() to dispose the sequence from within an onNext implementation.

Like all other consumers, ResourceObserver can be subscribed only once. Any subsequent attempt to subscribe it to a new source will yield an IllegalStateException with message "It is not allowed to subscribe with a(n) <class name> multiple times.".

Implementation of onStart(), Observer.onNext(Object), Observer.onError(Throwable) and Observer.onComplete() are not allowed to throw any unchecked exceptions. If for some reason this can't be avoided, use Observable.safeSubscribe(io.reactivex.rxjava3.core.Observer) instead of the standard subscribe() method.

Example

 Disposable d =
     Observable.range(1, 5)
     .subscribeWith(new ResourceObserver<Integer>() {
         @Override public void onStart() {
             add(Schedulers.single()
                 .scheduleDirect(() -> System.out.println("Time!"),
                     2, TimeUnit.SECONDS));
             request(1);
         }
         @Override public void onNext(Integer t) {
             if (t == 3) {
                 dispose();
             }
             System.out.println(t);
         }
         @Override public void onError(Throwable t) {
             t.printStackTrace();
             dispose();
         }
         @Override public void onComplete() {
             System.out.println("Done!");
             dispose();
         }
     });
 // ...
 d.dispose();
 

Constructor Summary

Constructors

Constructor and Description
ResourceObserver()

Method Summary

Modifier and Type	Method and Description
void	add(@NonNull Disposable resource) Adds a resource to this ResourceObserver.
void	dispose() Cancels the main disposable (if any) and disposes the resources associated with this ResourceObserver (if any).
boolean	isDisposed() Returns true if this ResourceObserver has been disposed/cancelled.
protected void	onStart() Called once the upstream sets a Disposable on this ResourceObserver.
void	onSubscribe(Disposable d) Provides the Observer with the means of cancelling (disposing) the connection (channel) with the Observable in both synchronous (from within Observer.onNext(Object)) and asynchronous manner.

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.reactivex.rxjava3.core.Observer

onComplete, onError, onNext

Methods inherited from interface io.reactivex.rxjava3.disposables.Disposable

disposed, empty, fromAction, fromAutoCloseable, fromFuture, fromFuture, fromRunnable, fromSubscription, toAutoCloseable

Constructor Detail

ResourceObserver

public ResourceObserver()

Method Detail

add

public final void add(@NonNull
                      @NonNull Disposable resource)

Adds a resource to this ResourceObserver.

Parameters:

resource - the resource to add

Throws:

NullPointerException - if resource is null

onSubscribe

public final void onSubscribe(Disposable d)

Description copied from interface: Observer

Provides the Observer with the means of cancelling (disposing) the connection (channel) with the Observable in both synchronous (from within Observer.onNext(Object)) and asynchronous manner.

Specified by:

onSubscribe in interface Observer<T>

Parameters:

d - the Disposable instance whose Disposable.dispose() can be called anytime to cancel the connection

onStart

protected void onStart()

Called once the upstream sets a Disposable on this ResourceObserver.

You can perform initialization at this moment. The default implementation does nothing.

dispose

public final void dispose()

Cancels the main disposable (if any) and disposes the resources associated with this ResourceObserver (if any).

This method can be called before the upstream calls onSubscribe(Disposable) at which case the main Disposable will be immediately disposed.

Specified by:

dispose in interface Disposable

isDisposed

public final boolean isDisposed()

Returns true if this ResourceObserver has been disposed/cancelled.

Specified by:

isDisposed in interface Disposable

Returns:

true if this ResourceObserver has been disposed/cancelled