src/main/java/io/reactivex/Observable.java
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<T> onErrorResumeNext(final ObservableSource<? extends T> next) {
        ObjectHelper.requireNonNull(next, "next is null");
        return onErrorResumeNext(Functions.justFunction(next));
    }
@CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public final Observable<T> onErrorResumeNext(final ObservableSource<? extends T> next) {
        ObjectHelper.requireNonNull(next, "next is null");
        return onErrorResumeNext(Functions.justFunction(next));
    }
@ CheckReturnValue @ SchedulerSupport ( SchedulerSupport . NONE ) public final Observable < T > onErrorResumeNext ( final ObservableSource < ? extends T > next ) { ObjectHelper . requireNonNull ( next , "next is null" ) ; return onErrorResumeNext ( Functions . justFunction ( next ) ) ; }
Instructs an ObservableSource to pass control to another ObservableSource rather than invoking
{@link Observer#onError onError} if it encounters an error.
<p>
<img width="640" height="310" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/onErrorResumeNext.png" alt="">
<p>
By default, when an ObservableSource encounters an error that prevents it from emitting the expected item to
its {@link Observer}, the ObservableSource invokes its Observer's {@code onError} method, and then quits
without invoking any more of its Observer's methods. The {@code onErrorResumeNext} method changes this
behavior. If you pass another ObservableSource ({@code resumeSequence}) to an ObservableSource's
{@code onErrorResumeNext} method, if the original ObservableSource encounters an error, instead of invoking its
Observer's {@code onError} method, it will instead relinquish control to {@code resumeSequence} which
will invoke the Observer's {@link Observer#onNext onNext} method if it is able to do so. In such a case,
because no ObservableSource necessarily invokes {@code onError}, the Observer may never know that an error
happened.
<p>
You can use this to prevent errors from propagating or to supply fallback data should errors be
encountered.
<dl>
<dt><b>Scheduler:</b></dt>
<dd>{@code onErrorResumeNext} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>

@param next
the next ObservableSource source that will take over if the source ObservableSource encounters
an error
@return the original ObservableSource, with appropriately modified behavior
@see <a href="http://reactivex.io/documentation/operators/catch.html">ReactiveX operators documentation: Catch</a>
Instructs an ObservableSource to pass control to another ObservableSource rather than invoking { @link Observer#onError onError } if it encounters an error . <p > <img width = 640 height = 310 src = https : // raw . github . com / wiki / ReactiveX / RxJava / images / rx - operators / onErrorResumeNext . png alt = > <p > By default when an ObservableSource encounters an error that prevents it from emitting the expected item to its { @link Observer } the ObservableSource invokes its Observer s { @code onError } method and then quits without invoking any more of its Observer s methods . The { @code onErrorResumeNext } method changes this behavior . If you pass another ObservableSource ( { @code resumeSequence } ) to an ObservableSource s { @code onErrorResumeNext } method if the original ObservableSource encounters an error instead of invoking its Observer s { @code onError } method it will instead relinquish control to { @code resumeSequence } which will invoke the Observer s { @link Observer#onNext onNext } method if it is able to do so . In such a case because no ObservableSource necessarily invokes { @code onError } the Observer may never know that an error happened . <p > You can use this to prevent errors from propagating or to supply fallback data should errors be encountered . <dl > <dt > <b > Scheduler : < / b > < / dt > <dd > { @code onErrorResumeNext } does not operate by default on a particular { @link Scheduler } . < / dd > < / dl >