> -----Original Message-----
> From: Berin Loritsch [mailto:[EMAIL PROTECTED]
> Sent: Freitag, 7. März 2003 18:50
> To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
> Subject: Re: Coding style question: backwards null checks
>
> > if ( "something".equals(stringToCompare) {
> > ...
> > }
> >
> > IMO it seems more straightforward and easier to read if it's:
> >
> > if ( stringToCompare.equals("something") ) {
> > ...
> > }
>
> Actually, this *does* have a purpose. In the event that
> stringToCompare is null, then you would get spurious
> NullPointerExceptions that are not always easy to trace.
>
> The "something".equals(somethingElse) guarantees that
> you won't get the NullPointerException every time without
> resorting to the longer form of:
>
> if ( stringToCompare != null &&
> stringToCompare.equals("something") ) {
> ....
> }
>
> It's a lot more typing to be _truly_ functionally
> equivalent. The compiler cannot guarantee that
> the stringToCompare variable is never null, so it
> will not give you a warning.
I'd say this is no longer a matter of taste but of methodology.
If you write
stringToCompare != null && stringToCompare.equals("something")
you state clearly that you expect it may be null and how to deal
with it. Saying that you write
"something".equals(stringToCompare)
because you *know* from long years of experience that it is
equivalent, gains you an entry in the Java obfuscation contest.
(I am fairly seasoned Java programmer but I had to look up docs
to convince myself that equals(null) wouldn't throw an exception.)
A null string being different to any other string may be in some
cases a useful convention, in other cases it hides a logic error.
Let the code state clearly what your intentions are and let it fail
with NPE, if you don't expect handle nulls.
NB my stanza for repeatedly writing non-null checks is:
if( stringToCompare == null )
stringToCompare = "";
if( stringToCompare.equals("something") ) {
...
}
Cheers, Alfred.
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