Helper classes (original) (raw)
Stephen Colebourne scolebourne at joda.org
Mon Apr 15 14:54:50 PDT 2013
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On 15 April 2013 22:41, Brian Goetz <brian.goetz at oracle.com> wrote:
An example of a method at the other end of the spectrum is Collections.rotate(List, int). Sure, this is useful when you need it, but it just isn't that important, and weighing down an interface with 5000 lines of additional code (OK, Collections is only 4700 LoC) really clogs up the Collection interface.
Perhaps there is a semblance of a first rule here.
- Collections.rotate(List, int) - static could now be:
- List.rotate(List, int) - static but that would just look and behave weirdly, because it should be
- List.rotate(int) - instance
But, most of us would agree that an instance method for rotating probably isn't justified. Thus it is also not justified as a static method on the same interface.
The rule is therefore along the lines of "don't add a static method where one of its arguments is the same type as the interface and the methods purpose is to operate on that argument. Either use a default instance method on the interface, or keep it in a separate utility class".
Stephen
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