[PROPOSAL][JDK10] Introduce Executable.getParameterType(index)

[Alan Bateman]

On 03/11/2017 08:11, Christoph Dreis wrote:
> Hi John,
>
>>> this has a bigger impact on the overall footprint of Method/Executable objects. What are your thoughts on this?
>> The footprint is probably about the same.  Small List.of values
>> do not contain arrays, and may be smaller than arrays with the
>> same number of elements, since they do not have a length field.
>> And, indeed, methods typically have a small number of parameters.
> Ah, so you would remove the current array field completely and replace it with the immutable List, right?
> In that case I said nothing. I was thinking of a field on top.
>
The VM creates Method objects and sets the fields, including 
parameterTypes, directly so I think removing it would require more work 
than it initially looks. If you add a field then it does increase the 
footprint a bit. Alternatively, have the method could use a 
ImmutableCollection.ListN like implementation that is backed by the 
array and doesn't scan it for nulls at create time, this wouldn't be 
completely allocation free of course.

In any case, the proposed API does look reasonable although it 
deviations from the usual conventions in java.lang.reflect.

-Alan