Objects.nonNull()

[Brian Goetz]

Thinking some more:

  - The name nonNull() is just confusing.  It could reasonably mean one 
of several things, and we've seen this in people's reactions: some don't 
like it for the throwing behavior because its not clear that it has a 
strong checking behavior, others don't like it for the defaulting 
behavior because the find the defaulting behavior unnatural.  This 
suggests it is just too vague to make anyone happy.
  - I'm still enamored of checkNonNull() for the throwing version but am 
still open to better names.
  - If we add carpet-sweeping versions later, asNonNull() or 
makeNonNull() both seem better than nonNull().
  - We just stay away from the not-specific-enough name nonNull() here.



On 1/13/2011 7:20 PM, mark.reinhold at oracle.com wrote:
>> Date: Thu, 13 Jan 2011 18:15:30 -0500
>> From: brian.goetz at oracle.com
>
>> ...
>>
>> Between checkNonNull() and throwIfNull(), I lean towards the former.  In any
>> case the answer should be driven by what is more obvious to the reader.
>
> Agreed.
>
>>                                                                           So
>> let's look at some typical code:
>>
>>    public Moo fooWrapper(String x, String y) {
>>        return foo(throwIfNull(x), throwIfNull(y));
>>    }
>>
>> vs
>>
>>    public Moo fooWrapper(String x, String y) {
>>        return foo(checkNonNull(x), checkNonNull(y));
>>    }
>>
>> Since throwing should be the exceptional path, it feels to me that having throw
>> in the name sets slightly the wrong expectations.  ...
>
> Agreed.
>
> I'm still troubled by the "check" prefix, though.  It implies that the
> named condition will be tested but it doesn't clearly relate the result
> of that test to the method's exception-throwing behavior.
>
> Here's an idea: Why not treat this as a (degenerate) kind of conversion
> operation?  Call it asNonNull(x) -- it (trivially) converts its argument
> to a non-null value, and if it can't then it throws an NPE.
>
>    public Moo fooWrapper(String x, String y) {
>        return foo(asNonNull(x), asNonNull(y));
>    }
>
> Of all the names we've considered, this looks the most natural to me.
>
> - Mark