Package org.eclipse.microprofile.reactive.streams.operators

Interface ErrorHandlingOperators<T>

  • Type Parameters:
    T - The type of the elements that the stream emits.
    All Known Subinterfaces:
    ProcessorBuilder<T,​R>, PublisherBuilder<T>
    public interface ErrorHandlingOperators<T>
    Operators for handling errors in streams.

    The documentation for each operator uses marble diagrams to visualize how the operator functions. Each element flowing in and out of the stream is represented as a coloured marble that has a value, with the operator applying some transformation or some side effect, termination and error signals potentially being passed, and for operators that subscribe to the stream, an output value being redeemed at the end.

    Below is an example diagram labelling all the parts of the stream.

    Example marble diagram

    See Also:
    ReactiveStreams

    • Method Detail

      • onErrorResume

        ErrorHandlingOperators<T> onErrorResume​(java.util.function.Function<java.lang.Throwable,​? extends T> errorHandler)
        Returns a stream containing all the elements from this stream. Additionally, in the case of failure, it invokes the given function and emits the result as final event of the stream.

        onErrorResume marble diagram

        By default, when a stream encounters an error that prevents it from emitting the expected item to its subscriber, the stream invokes its subscriber's onError method, and then terminates without invoking any more of its subscriber's methods. This operator changes this behavior. If the current stream encounters an error, instead of invoking its subscriber's onError method, it will instead emit the return value of the passed function. This operator prevents errors from propagating or to supply fallback data should errors be encountered.

        Parameters:
        errorHandler - the function returning the value that needs to be emitting instead of the error. The function must not return null.
        Returns:
        The new stream builder.

      • onErrorResumeWith

        ErrorHandlingOperators<T> onErrorResumeWith​(java.util.function.Function<java.lang.Throwable,​? extends PublisherBuilder<? extends T>> errorHandler)
        Returns a stream containing all the elements from this stream. Additionally, in the case of failure, it invokes the given function and emits the elements from the returned PublisherBuilder instead.

        onErrorResumeWith marble diagram

        By default, when a stream encounters an error that prevents it from emitting the expected item to its subscriber, the stream invokes its subscriber's onError method, and then terminates without invoking any more of its subscriber's methods. This operator changes this behavior. If the current stream encounters an error, instead of invoking its subscriber's onError method, it will instead relinquish control to the PublisherBuilder returned from the given function, which invokes the subscriber's onNext method if it is able to do so. The subscriber's original Subscription is used to control the flow of elements both before and after any error occurring. In such a case, because no publisher necessarily invokes onError on the stream's subscriber, it may never know that an error happened.

        Parameters:
        errorHandler - the function returning the stream that needs to be emitting instead of the error. The function must not return null.
        Returns:
        The new stream builder.

      • onErrorResumeWithRsPublisher

        ErrorHandlingOperators<T> onErrorResumeWithRsPublisher​(java.util.function.Function<java.lang.Throwable,​? extends org.reactivestreams.Publisher<? extends T>> errorHandler)
        Returns a stream containing all the elements from this stream. Additionally, in the case of failure, it invokes the given function and emits the elements from the returned Publisher instead.

        onErrorResumeWithRsPublisher marble diagram

        By default, when a stream encounters an error that prevents it from emitting the expected item to its subscriber, the stream invokes its subscriber's onError method, and then terminates without invoking any more of its subscriber's methods. This operator changes this behavior. If the current stream encounters an error, instead of invoking its subscriber's onError method, the subscriber will be fed from the Publisher returned from the given function, and the subscriber's onNext method is called as the returned Publisher publishes. The subscriber's original Subscription is used to control the flow of both the original and the onError Publishers' elements. In such a case, because no publisher necessarily invokes onError, the subscriber may never know that an error happened.

        Parameters:
        errorHandler - the function returning the stream that need to be emitting instead of the error. The function must not return null.
        Returns:
        The new stream builder.