Thread: [Codenarc-developer] UnnecessaryEqualityWithNull rule

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codenarc-developer

[Codenarc-developer] UnnecessaryEqualityWithNull rule

From: Chris M. <chr...@ea...> - 2011-06-04 15:06:02

The documentation for UnnecessaryEqualityWithNull  says

The expression object.equals(null) is always false and is unnecessary.

The object.equals(null) comparison will always return false, since the
object is not null. (If the object is null, the program will throw a
NullPointerException). This is the basic contract of the equals() method.

 

But this prints true in the GroovyConsole, rather than throwing a NPE:

 

def x = null

println x.equals(null)

 

Any thoughts on what to do with this rule?

Re: [Codenarc-developer] UnnecessaryEqualityWithNull rule

From: Hamlet D. <ham...@ca...> - 2011-06-06 05:31:02

I never thought of this scenario. 

However, isn't 
  x.equals(null)
and 
  x == null
the same thing? 

I'd prefer the latter. 


----- Original Message -----
> 
> 
> 
> 
> The documentation for UnnecessaryEqualityWithNull says
> 
> The expression object.equals(null) is always false and is
> unnecessary.
> 
> The object.equals(null) comparison will always return false, since
> the object is not null. (If the object is null, the program will
> throw a NullPointerException). This is the basic contract of the
> equals() method.
> 
> 
> 
> But this prints true in the GroovyConsole, rather than throwing a
> NPE:
> 
> 
> 
> def x = null
> 
> println x.equals(null)
> 
> 
> 
> Any thoughts on what to do with this rule?
> ------------------------------------------------------------------------------
> Simplify data backup and recovery for your virtual environment with
> vRanger.
> Installation's a snap, and flexible recovery options mean your data
> is safe,
> secure and there when you need it. Discover what all the cheering's
> about.
> Get your free trial download today.
> http://p.sf.net/sfu/quest-dev2dev2
> _______________________________________________
> Codenarc-developer mailing list
> Cod...@li...
> https://lists.sourceforge.net/lists/listinfo/codenarc-developer
>

Re: [Codenarc-developer] UnnecessaryEqualityWithNull rule

From: <chr...@we...> - 2011-06-06 11:45:38

I prefer x == null, too. But that "preference" is already handled by the ExplicitCallToEqualsMethod rule, right?

I'm not sure I see the value in the UnnecessaryEqualityWithNull rule, given how Groovy does let you call equals() on null. 

-----Original Message-----
From: Hamlet DArcy [mailto:ham...@ca...] 
Sent: Monday, June 06, 2011 1:31 AM
To: Chris Mair
Cc: cod...@li...
Subject: Re: [Codenarc-developer] UnnecessaryEqualityWithNull rule

I never thought of this scenario. 

However, isn't 
  x.equals(null)
and 
  x == null
the same thing? 

I'd prefer the latter. 


----- Original Message -----
> 
> 
> 
> 
> The documentation for UnnecessaryEqualityWithNull says
> 
> The expression object.equals(null) is always false and is
> unnecessary.
> 
> The object.equals(null) comparison will always return false, since
> the object is not null. (If the object is null, the program will
> throw a NullPointerException). This is the basic contract of the
> equals() method.
> 
> 
> 
> But this prints true in the GroovyConsole, rather than throwing a
> NPE:
> 
> 
> 
> def x = null
> 
> println x.equals(null)
> 
> 
> 
> Any thoughts on what to do with this rule?
> ------------------------------------------------------------------------------
> Simplify data backup and recovery for your virtual environment with
> vRanger.
> Installation's a snap, and flexible recovery options mean your data
> is safe,
> secure and there when you need it. Discover what all the cheering's
> about.
> Get your free trial download today.
> http://p.sf.net/sfu/quest-dev2dev2
> _______________________________________________
> Codenarc-developer mailing list
> Cod...@li...
> https://lists.sourceforge.net/lists/listinfo/codenarc-developer
> 

------------------------------------------------------------------------------
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Installation's a snap, and flexible recovery options mean your data is safe,
secure and there when you need it. Discover what all the cheering's about.
Get your free trial download today. 
http://p.sf.net/sfu/quest-dev2dev2 
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Re: [Codenarc-developer] UnnecessaryEqualityWithNull rule

From: Hamlet D. <ham...@ca...> - 2011-06-06 12:17:34

I think, as is currently stands, you are correct. 
For it to be useful we need to find things like: 

def x = 'x'
def y = 'y'
x = null
if (y.equals(x)) {
    ...
}

Which we don't have yet (but at some point would be nice). 



----- Original Message -----
> I prefer x == null, too. But that "preference" is already handled by
> the ExplicitCallToEqualsMethod rule, right?
> 
> I'm not sure I see the value in the UnnecessaryEqualityWithNull rule,
> given how Groovy does let you call equals() on null.
> 
> -----Original Message-----
> From: Hamlet DArcy [mailto:ham...@ca...]
> Sent: Monday, June 06, 2011 1:31 AM
> To: Chris Mair
> Cc: cod...@li...
> Subject: Re: [Codenarc-developer] UnnecessaryEqualityWithNull rule
> 
> I never thought of this scenario.
> 
> However, isn't
>   x.equals(null)
> and
>   x == null
> the same thing?
> 
> I'd prefer the latter.
> 
> 
> ----- Original Message -----
> > 
> > 
> > 
> > 
> > The documentation for UnnecessaryEqualityWithNull says
> > 
> > The expression object.equals(null) is always false and is
> > unnecessary.
> > 
> > The object.equals(null) comparison will always return false, since
> > the object is not null. (If the object is null, the program will
> > throw a NullPointerException). This is the basic contract of the
> > equals() method.
> > 
> > 
> > 
> > But this prints true in the GroovyConsole, rather than throwing a
> > NPE:
> > 
> > 
> > 
> > def x = null
> > 
> > println x.equals(null)
> > 
> > 
> > 
> > Any thoughts on what to do with this rule?
> > ------------------------------------------------------------------------------
> > Simplify data backup and recovery for your virtual environment with
> > vRanger.
> > Installation's a snap, and flexible recovery options mean your data
> > is safe,
> > secure and there when you need it. Discover what all the cheering's
> > about.
> > Get your free trial download today.
> > http://p.sf.net/sfu/quest-dev2dev2
> > _______________________________________________
> > Codenarc-developer mailing list
> > Cod...@li...
> > https://lists.sourceforge.net/lists/listinfo/codenarc-developer
> > 
> 
> ------------------------------------------------------------------------------
> Simplify data backup and recovery for your virtual environment with
> vRanger.
> Installation's a snap, and flexible recovery options mean your data
> is safe,
> secure and there when you need it. Discover what all the cheering's
> about.
> Get your free trial download today.
> http://p.sf.net/sfu/quest-dev2dev2
> _______________________________________________
> Codenarc-developer mailing list
> Cod...@li...
> https://lists.sourceforge.net/lists/listinfo/codenarc-developer
>