Does it matter whether I extend `Exception` or `Ru...

# getting-started

[poohbar]

Does it matter whether I extend Exception or RuntimeException in Kotlin? I thought it doesn't but my Exception extension is getting wrapped in UndeclaredThrowableException when interacting with a Java library.

[Vampire]

For Java interop there is @Throws annotation

[Tobias Berger]

Well, it doesn't really matter in Kotlin (unless you have a catch-Block for explicitly for RuntimeException of course), but the error you get is thrown by Java code. If your Kotlin exception ends up in some Java code, it can make a difference.
So if you're wprking with Kotlin exceptions in combination with Java code or libs, it's a good idea to either us RuntimeExceptions or @Throws(MyException::class) as suggested by @Vampire (equivalent of adding throws MyException to the end of a method signature in Java)

[spand]

Since Kotlin mirrors the Java exception hierarchy I would say you should do the same as you would in Java.

[Tobias Berger]

Kotlin doesn't differentiate between checked and unchecked exceptions, so unless you have Java inter-op there is no need to use RuntimeException