Learning RxJava - Second Edition

onErrorReturnItem() and onErrorReturn()

When you want to resort to a default value when an exception occurs, you can use the onErrorReturnItem() operator. If we want to emit -1 when an exception occurs, we can do it like this:

import io.reactivex.rxjava3.core.Observable;public class Ch3_42 {    public static void main(String[] args) {        Observable.just(5, 2, 4, 0, 3)               .map(i -> 10 / i)               .onErrorReturnItem(-1)               .subscribe(i -> System.out.println("RECEIVED: " + i),                    e -> System.out.println("RECEIVED ERROR: " + e));    }}

The output of the preceding code snippet is as follows:

RECEIVED: 2RECEIVED: 5RECEIVED: 2RECEIVED: -1

You can see that the emissions stopped after the error anyway, but the error itself did not flow down to the Observer. Instead, ...