Error handling

The Observables contain a couple of operators that allow error handling, swallowing exceptions, transforming exceptions, call-finally blocks, retrying the failed sequence, and disposing resources even if an error occurs.

The catch operator

These operators enable recovering from errors by continuing the sequence:

• onErrorResumeNext: Instructs an Observable to pass control to another Observable given by a supplier, instead of invoking onError when something goes wrong
• onErrorReturn: Instructs an Observable to emit a default supplied by a function, in case of error
• onErrorReturnItem: Instructs an Observable to emit a supplied default, in case of error
• onExceptionResumeNext: Instructs an Observable to pass control to another Observable instead of invoking onError in case something goes wrong

The following example shows how to use the onErrorReturnItem method; calling it without the flatMap trick will stop the flow and output Default at the end. By deferring the call to the exception...