Java keyword "super"

[trent shipley]

"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 at 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 at 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 at gmail.com
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