Are SystemExceptions and ApplicationException in Mono the same as unchecked and checked exception in Java?

Question

In Java, there are two types of Exceptions, mainly unchecked and checked exceptions. Checked exceptions allow the program to recover when they are caught and handled in a ‘catch’ block. Unchecked exceptions just cause your program to crash, since they are not caught and the error bubbles up all the way got the main method without being caught, if I recall correctly.

That said, in Mono, there are ApplicationExceptions and SystemExceptions and I was wondering if these serve the same purpose in mono.

Well Mono is based on .NET and you can write C# to produce bytecode for that, so sure, why not? — leeand00, May 02 '19 at 03:34
Well I ask because in Java the distinction between checked and unchecked exceptions is only enforced by the Java bytecode compiler. — Stephen C, May 02 '19 at 03:45
I’m checking really only to see if the distinction would crash a running program (if SystemException was thrown instead of an ApplicationException) — leeand00, May 02 '19 at 03:48

Stephen C · Answer 1 · 2019-07-21T05:52:52.223

No they are not. The distinctions are different.

In Java, the checked versus unchecked distinction is about whether Java code needs to deal with the exception:

unchecked exceptions don't need to be dealt with
checked exceptions need to be either caught or declared in the signature of the enclosing method.

(You should chose between declaring an exception as checked or unchecked according to whether you expect / want the caller to handle it. For example, you typically want the app to do something to recover from an IOException, but a NullPointerException is usually a bug and cannot be handled beyond logging and bailing out.)

By contrast, ApplicationExceptions versus SystemExceptions in .NET is about the meaning of the exceptions; see Difference Between Application Exception and System Exception. The ostensible purpose was to allow a program to distinguish between framework and custom exceptions. (But it doesn't really work ... in practice ... because programmers don't follow the guidelines / conventions.)

I'm checking really only to see if the distinction would crash a running program if SystemException was thrown instead of an ApplicationException

You can't make that generalization. The application crashes if either kind of exception (or any other kind) is thrown and not caught¹. And that is true for Java exceptions as well.

^{1 - In Java, this depends on the behavior of the default exception handler.}

Are SystemExceptions and ApplicationException in Mono the same as unchecked and checked exception in Java?

1 Answers1