Throw statement in Reactive operator

Reports throw expressions in the Reactor/RxJava operator code.

Throwing exceptions from a Reactor/RxJava operator indicates a possible problem, because you can return a "Reactive-like" error: Mono.error() or Flowable.error() from flatMap(), or call sink.error() from the Reactor's handle() operator.

Also, Reactor factory methods allow returning checked exceptions without any errors, while throwing such exceptions without the Exceptions class leads to a compilation error.

Example:

Flux.just(1, 2, 3).flatMap(i -> {
            throw new RuntimeException();
        })

After the quick-fix is applied:

Flux.just(1, 2, 3).flatMap(i -> {
            return Flux.error(new RuntimeException());
        })

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

ReactiveStreamsThrowInOperator

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Reactive Streams | Common

New in 2019.3

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection ReactiveStreamsThrowInOperator

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2025.2

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.2, Qodana for JVM 2025.2,

Last modified: 18 September 2025