Re: Exception handling

From:

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 27 Nov 2009 20:40:49 -0500

Message-ID:

<4b107f95$0$283$14726298@news.sunsite.dk>

Daniel Pitts wrote:

Andre Rothe wrote:

I try to find some information about a best-practice exception
framework. Maybe this group can help me.

An application throws an exception within a low-level method, let us
say, within a database access layer. It has occured as reaction of a
wrong value given by the user. The method can throw the exception, the
next higher abstraction layer can rollback the associated database
operation and throw it up to the client application.

This is a bad pattern.

The low-level methods should through exceptions which indicate
programmer error. Higher-level methods should validate *before* calling
lower-level methods.

That is not always possible.

Of course, this is all idealized. Sometimes it is infeasible to verify
user-input before calling the lower-level method. In which case, the
lower-level method can still throw a "low-level" exception, but it
should still be translated into "high-level" message by the higher level
code.

Yep.

Arne