Richard,
You right. (null == s) works. However, when I try (null != s) it fails wiht
an exception. Interesting. Thanks.
John D. McDonald
CipherStream Systems
Phone: 925.373.8700
Fax: 413.793.6603
email: [EMAIL PROTECTED]
web: www.cipherstream.com
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----- Original Message -----
From: Richard Clark <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, January 05, 2000 4:56 PM
Subject: Re: Checking for null
> Look at my code again...
>
> if (null == s || s.length() == 0) ...
>
> Java translates x == y into x.equals(y). If I had said
> if (s == null)
> and s was null, you would get a null pointer exception. However, the
> constant null is handled specially -- it has an equals method that always
> works. Thus, saying
> if (null == s)
> will not fail with a null pointer exception.
>
> I also used the short-circuiting "or" operator || to connect the two
pieces.
> In effect, a || b means "if a evaluates to false, evaluate b."
>
> In a case like this, || often leads to cleaner and more efficient code
than
> nesting "if" statements.
>
> By the way, you could also say:
> if (null != s && s.length() != 0)
> which would yield the same result as Mark'code below.
>
> ...Richard
>
>
> -----Original Message-----
> From: Mark Foley [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, January 05, 2000 4:22 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [SERVLET-INTEREST] Checking for null
>
>
> Hi,
>
> Wouldn't your conditional statement cause a null pointer exception if s is
> null? Try it!
>
> I do this:
> ...
> if(null != s) {
> if(s.length() != 0) {
> // it's not null and it's not empty
> }
> }
>
> Regards,
> Mark
>
>
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