Class ResourceMaybeObserver<T>

java.lang.Object
io.reactivex.rxjava4.observers.ResourceMaybeObserver<T>
Type Parameters:
T - the value type
All Implemented Interfaces:
MaybeObserver<T>, Disposable
public abstract class ResourceMaybeObserver<T> extends Object implements MaybeObserver<T>, 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) <class name> 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<Integer>() {
        @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 Details

    • ResourceMaybeObserver

      public ResourceMaybeObserver()

  • Method Details

    • 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