Re: Why shouldn't we catch class RuntimeException?

From:
Robert Klemme <shortcutter@googlemail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 12 Jun 2007 17:26:06 +0200
Message-ID:
<5d7s85F33n5vlU1@mid.individual.net>
On 12.06.2007 16:47, kaja_love160@yahoo.com wrote:

Book I???m learning from claims that exceptions of type RuntimeException
and its children are thrown due to bad programming and should be
avoided by writing better code. One such exception of type
RuntimeException might happen when a user is asked to enter a value
and user enters an invalid value ??? this may cause runtime exception.
We can go about it in two ways:

1) by writing "if ( correct input ) .. else"
2) or by throwing and catching an exception

Now according to my book ( as I understood it ) we should use
something like : if ( correct input ) .. else ??? to deal with this
problem and not use exceptions. Why shouldn???t exceptions be used for
such cases?


Usually the front end is considered responsible for making sure only
proper data enters the system. That way you can prompt the user with a
much more meaningful error message. It's double checking in a way - but
the class should make sure instance state stays consistent, so usually
setter methods throw if presented illegal data. The UI check should be
there to additionally make sure the user gets informed what he did wrong
("you did not enter a number in field 'ZIP code'" which is better than
an error you might be seeing from the application like "not numeric").

Kind regards

    robert

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