Yesterday I send an email to some friends about a particular Java feature. The original email read "JDK 1.5 has introduced a cool feature to allow overriden methods to have different return types". I had just read about this feature in a newsletter and decided to share it.
However just before clicking on the 'Send' button, I decided to review the mail to ensure that it was correctly phrased (I always have to review my first draft... even if it's just a line :-). While reading it again, I stopped at the word 'cool', and thought to myself - Is this a cool feature, or is it just a feature. Was the use of 'cool' appropriate here? This made me think a bit more about this feature. This feature was intended to remove the hassle of downcasting an object returned from a method. But wouldn't different return types for overriden methods break the "program to an interface" concept? Now the client code has to know the exact subclass that it is calling. Polymorphism is supposed to rid us of those long if...else statements, but to make use of this feature we will have to depend on them to tell us which subclass we have instantiated and are invoking a method of.
Now this feature does not look all that cool. Actually it seems that there is little purpose to this feature, except making the language more complex.
I was able to think this over because I decided to write about it... otherwise it still may have been a cool new feature for me. Offcourse it could still be a cool feature and I am open to a different perspective. But the point is that the process of writing helped me crystallize a concept which would not have happened otherwise.
Do drop in a note to tell me what you think about writing or about this new Java feature.