Question

Instead of throwing new Exception("Some message", maybeSomeCause), which means that all callers of my method will need to catch Exception (which can include RuntimeExceptions), I’d like to throw a more specific type of exception when a problem occurs.

I can create my own exception types which extend Exception or another exception type, but I am curious if it is a good idea to re-use some exceptions that come with core Java language, such as:

• IllegalArgumentException
• UnsupportedOperationException
• IOException
• Others?

Are there others that I am missing? I found a basic list of the ‘core’ exceptions here: http://rymden.nu/exceptions.html, with humous explanations.

Thanks!

Edit:

Is there a good list of ‘core’ exceptions?

List so far:

• http://rymden.nu/exceptions.html
• Java 7 Exception class API

Answer 1

Yes, it’s very good to do that. In fact, it’s even written about in Effective Java, 2nd ed. See item 60 on page 248: “Favor the use of standard exceptions”

Reusing preexisting exceptions has several benefits. Chief among
these, it makes your API easier to learn and use because it matches
established conventions with which programmers are already familiar. A
close second is that programs using your API are easier to read
because they aren’t cluttered with unfamiliar exceptions. Last (and
least), fewer exception classes mean a smaller memory footprint and
less time spent loading classes.