Package io.reactivex.rxjava3.observers

Class DefaultObserver<T>

  • Type Parameters:
    T - the value type
    All Implemented Interfaces:
    Observer<T>
    Direct Known Subclasses:
    BlockingObservableMostRecent.MostRecentObserver
    public abstract class DefaultObserver<T>
extends java.lang.Object
implements Observer<T>
    Abstract base implementation of an Observer with support for cancelling a subscription via cancel() (synchronously) and calls onStart() when the subscription happens.

    All pre-implemented final methods are thread-safe.

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

    Like all other consumers, DefaultObserver 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

    
 Observable.range(1, 5)
     .subscribe(new DefaultObserver<Integer>() {
         @Override public void onStart() {
             System.out.println("Start!");
         }
         @Override public void onNext(Integer t) {
             if (t == 3) {
                 cancel();
             }
             System.out.println(t);
         }
         @Override public void onError(Throwable t) {
             t.printStackTrace();
         }
         @Override public void onComplete() {
             System.out.println("Done!");
         }
     });

    • Constructor Summary

      Constructors 
      Constructor Description
      DefaultObserver()  

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      protected void cancel()
      Cancels the upstream's disposable.
      protected void onStart()
      Called once the subscription has been set on this observer; override this to perform initialization.
      void onSubscribe​(@NonNull 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

    • Constructor Detail

      • DefaultObserver

        public DefaultObserver()

    • Method Detail

      • cancel

        protected final void cancel()
        Cancels the upstream's disposable.

      • onStart

        protected void onStart()
        Called once the subscription has been set on this observer; override this to perform initialization.