RFR: 8243115: Spurious invalidations due to bug in IntegerBinding and other classes

[Nir Lisker]

On Tue, 12 May 2020 17:58:09 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

> I'm fine with doing a fix, but I need to know which one. Avoiding NPE's and silently doing nothing is IMHO not very
> desirable as this will give the user of the API no feedback that something went wrong.
> So I would prefer to fix this by documenting that these cases will result in a NPE.
> 
> The `bind` method has a similar issue -- it doesn't check its array elements for `null`, and will throw a NPE when
> attempting to add a listener to `null`. Again, I would just document the NPE so what is clearly a mistake doesn't go
> unnoticed.

I think that checking the array elements doesn't help much because by the time you can check them they will already be
used, and that will throw an NPE implicitly.

`bind` is no-op for `null` or 0-length arrays, but should have probably throw an NPE on the `null` case. The 0-length
check saves creating the `observer`, so I think it makes sense. `unbind` should probably only throw an NPE on `null`
arrays, but that happens implicitly anyway, so maybe there is no change needed unless it's for clarity because we can
add a custom error message.

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PR: https://git.openjdk.java.net/jfx/pull/198