First round of java.util.Objects for code review (bug 6797535)

[Eamonn McManus]

 > The spec, you mention, refers to the instance method equals(), but here
 > we are talking about static helpers.

The difference between Marek's suggestion and Joe's is what happens when
the equals(Object) method of a or b returns true for a null argument, and
that is what I was saying violates the spec.

Éamonn McManus · JMX Spec Lead · http://weblogs.java.net/blog/emcmanus


Ulf Zibis wrote:
> Am 09.10.2009 10:56, Eamonn McManus schrieb:
>> Hi,
>>
>> Marek Kozieł wrote:
>> >> +    public static boolean equals(Object a, Object b) {
>> >> +        return (a == b) || (a != null && a.equals(b));
>> >> +    }
>> >
>> > Hello,
>> > I would suggest other implementation of equals method:
>> >
>> >     public static boolean equals(Object a, Object b) {
>> >         if (a == null) return (b == null ? true : b.equals(null));
>> >         if (b == null) return a.equals(null);
>> >         return a.equals(b);
>> >     }
>> >
>> > This one could cover case when null is considered as object in object
>> > equals method [...]
>>
>> An equals implementation that can return true when its argument is 
>> null violates its contract since
>> it is not symmetric.  In fact, the spec of Object.equals specifically 
>> says that the method must
>> return false when the argument is null.
>>
> 
> The spec, you mention, refers to the instance method equals(), but here 
> we are talking about static helpers.
> 
> But anyway, I don't understand the point of Marek's implementation.
> 
> -Ulf
> 
>