Objects.toString [Re: What methods should go into a java.util.Objects class in JDK 7?]

[Eamonn McManus]

David Holmes - Sun Microsystems wrote:
 > So to me: String toString(Object o, String useIfNull) is the only method
 > that provides true utility in this case.

I agree with that, and would just suggest to the person specifying the method
to add a @see String#valueOf(Object).  I find that the behaviour of that method
is usually exactly what I want when the argument is null (and I find the idea of
representing null by an empty string aberrant, but there you go), so for people like
me but who might not have noticed String.valueOf this will save them from peppering
Objects.toString(x, "null") throughout their programs.

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


David Holmes - Sun Microsystems wrote:
> Joe,
> 
> Joseph D. Darcy said the following on 10/09/09 04:30:
>> System.out.println("" + referenceOfAnyType);
>>
>> will print "null" if referenceOfAnyType is null.
>>
>> This is what the platform has done since the beginning.
> 
> Yes because String concatenation can not tolerate null values appearing, 
> so it is defined to replace null with "null" (or replace a null from 
> o.toString() with "null"). And I suspect that "null" was chosen over "" 
> because it is then obvious when an unexpected null was encountered.
> 
> But Objects.toString(o) is not concerned with string concatenation so 
> doesn't have to mimic that behaviour.
> 
> Personally I'd only put in the two-arg variant because:
> 
> a) a one-arg that simply forwards to String.valueOf is redundant as 
> already discussed
> 
> b) a one-arg that hardwires the response to null (whether that be to 
> return null or "null") will simply force the programmer to either switch 
> to a different API or else add their own null handling logic - which 
> defeats the purpose of putting in these utility/convenience methods.
> 
> So to me: String toString(Object o, String useIfNull) is the only method 
> that provides true utility in this case.
> 
> David