"extends" used with a wildcard {"?"} such as SomeCollection<? extends T>
makes sense to me. After reading stackoverflow, I am only somewhat more
enlightened on what SomeCollection<? super T> means, how it is used, and
why one might want to use it.
Trent.
On Sat, May 21, 2016 at 6:18 PM James Mcphee <
jmcphe@gmail.com> wrote:
> Check the answer to this stackoverflow. It says it better than I can.
> http://stackoverflow.com/questions/3009745/what-does-the-question-mark-in-java-generics-type-parameter-mean
>
> On Sat, May 21, 2016 at 1:08 PM, trent shipley <trent.shipley@gmail.com>
> wrote:
>
>> Can anyone tell me what the keyword "super" does in this parameter list
>> for the constructor below? I can only find documentation for the more
>> mundane use when a method references an ancestor.
>>
>> public WeightedCollection(Comparator<? super E> comp)
>>
>>
>> package pcgen.base.util;
>>
>> <</ deleted stuff>>
>>
>> /**
>>
>> * Constructs an empty WeightedCollection with the given Comparator used to
>>
>> * establish equality and order in the WeightedCollection.
>>
>> *
>>
>> * @param comp
>>
>> * The Comparator this Set will use to determine equality and
>>
>> * order of the WeightedCollection
>>
>> */
>>
>> public WeightedCollection(Comparator<? super E> comp)
>>
>> {
>>
>> if (comp == null)
>>
>> {
>>
>> theData = new ListSet<WeightedItem<E>>();
>>
>> }
>>
>> else
>>
>> {
>>
>> theData = new TreeSet<WeightedItem<E>>(
>>
>> new WeightedItemComparator<E>(comp));
>>
>> }
>>
>> }
>>
>>
>>
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>
>
>
> --
> James McPhee
> jmcphe@gmail.com
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