Learning Android Development

Beyond Basic RxJava Error Handling

Beware! Not all errors are sent to onError!

Picture by RyanMcGuire on Pixarbay

Most who knows RxJava would love it because of its ability in encapsulating Error Handling on onError callback as shared in the blog below.

RxJava 2: Making error handling easy in Android (in Kotlin)

A simple example as below.

Single.just(getSomeData())
 .map { item -> handleMap(item) } 
 .subscribe(
        { result -> handleResult(result) }, 
        { error -> handleError(error) } // Expect all error capture 
    )

A quick thought would be, ya, all crash will be handled by handleError(error) call.

But it is not true!

1. Crashes on just()

Let’s start with something simple. Let’s say if the error crashes within getSomeData()

Single.just(getSomeData() /**🔥Crash🔥**/ )
   .map { item -> handleMap(item) } 
   .subscribe(
        { result -> handleResult(result) }, 
        { error -> handleError(error) } // Crash NOT caught ⛔️ 
    )