io.reactivex.rxjava3.observers

Class ResourceMaybeObserver

java.lang.Object

io.reactivex.rxjava3.observers.ResourceMaybeObserver

Type Parameters:

T - the value type

All Implemented Interfaces:

MaybeObserver, Disposable

public abstract class ResourceMaybeObserver
extends Object
implements MaybeObserver, Disposable

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

All pre-implemented final methods are thread-safe.

Note that MaybeObserver.onSuccess(Object), MaybeObserver.onError(Throwable) and MaybeObserver.onComplete() are exclusive to each other, unlike a regular Observer, and onComplete() is never called after an onSuccess().

Override the protected onStart() to perform initialization when this ResourceMaybeObserver is subscribed to a source.

Use the public dispose() method to dispose the sequence externally and release all resources.

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

Use add(Disposable) to associate resources (as Disposables) with this ResourceMaybeObserver 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 ResourceMaybeObserver and then add/remove resources to/from the CompositeDisposable freely.

Like all other consumers, ResourceMaybeObserver 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) multiple times.".

Implementation of onStart(), MaybeObserver.onSuccess(Object), MaybeObserver.onError(Throwable) and MaybeObserver.onComplete() are not allowed to throw any unchecked exceptions.

Example

 Disposable d =
     Maybe.just(1).delay(1, TimeUnit.SECONDS)
     .subscribeWith(new ResourceMaybeObserver() {
         @Override public void onStart() {
             add(Schedulers.single()
                 .scheduleDirect(() -> System.out.println("Time!"),
                     2, TimeUnit.SECONDS));
         }
         @Override public void onSuccess(Integer t) {
             System.out.println(t);
             dispose();
         }
         @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
ResourceMaybeObserver()

Method Summary

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

onComplete, onError, onSuccess

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

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

Constructor Detail

ResourceMaybeObserver

public ResourceMaybeObserver()

Method Detail

add

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

Adds a resource to this ResourceMaybeObserver.

Parameters:

resource - the resource to add

Throws:

NullPointerException - if resource is null

onSubscribe

public final void onSubscribe(@NonNull
                              @NonNull Disposable d)

Description copied from interface: MaybeObserver

Provides the MaybeObserver with the means of cancelling (disposing) the connection (channel) with the Maybe in both synchronous (from within onSubscribe(Disposable) itself) and asynchronous manner.

Specified by:

onSubscribe in interface MaybeObserver<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 ResourceMaybeObserver.

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 ResourceMaybeObserver (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 ResourceMaybeObserver has been disposed/cancelled.

Specified by:

isDisposed in interface Disposable

Returns:

true if this ResourceMaybeObserver has been disposed/cancelled