Ability to decorate ChangeListener

Martin Sladecek martin.sladecek at oracle.com
Mon Mar 24 14:36:36 UTC 2014

On 24.3.2014 15:24, Mario Ivankovits wrote:
> But, after this discussion I do not see why one ever used .equals() at all.
> Look, it does not fit my needs, I do not see any use-case where one would add an removeListener with asymmetric .equals() and thus it is better you use == I think.
> This clarifies that EXACTLY the added listener instance is required to remove any listener AND it gives no room to discussions like we had because the indention is perfectly clear - even to those reading JavaFX core code and bug fixing things in JavaFX.
> For me this would be fine and understandable - I will go the decorator-cache-map so I will be fine always.

One example might be in bidirectional binding. There's a special 
listener that takes the 2 properties that are bound together and it's 
equals returns true if the other listener is of the same class and it's 
two properties (no matter in what order) are identical. This way, you 
can just write Bindings.unbindBidirectional() and the internal 
implementation does not need to remember the listener instance anywhere. 
The equals() is symmetric in this case, but == would not work here.


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