.onErrorReturn() work in a similar fashion to .onErrorResumeNext(), but instead of using Observable to resume the flow, it takes the value unwrapped from the Observable. Consider the following example:

Observable.<String>error(new Error("Crash!"))
        .onErrorReturn(throwable -> "Return")
        .subscribe(item -> {
            log("subscribe", item);
        }, e -> log("subscribe", e));

We can see that we didn't need to wrap "Return" in the Observable class of any kind.