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Groups > comp.lang.java.programmer > #6291

Re: Generics for a multiplevalue hashmap

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On 7/19/2011 5:24 AM, Esmond Pitt wrote:
> On 19/07/2011 7:31 AM, Alexis Berry wrote:
>> public class MultipleValueHashMap<T, java.util.List<U>> implements
>> Map<T, java.util.List<U>> {
>
> public class MultipleValueHashMap<T, <L extends java.util.List<U>>>
> implements Map<T, L> ?


Well, this doesn't work for a couple of reasons.  First, in terms of 
syntax, you still have to declare U as a type parameter:

public class GenericTest<T, U, L extends List<U>>
         extends AbstractMap<T, List<U>> {

Secondly, "List" here is both an input and and output.  And going by 
PECS -- Producer Extends, Consumer Super -- you can't use just one.  So 
I think the default is just to try to get the right type there (List 
works) and be careful with your type declarations.

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Thread

Generics for a multiplevalue hashmap Alexis Berry <iamrichardjones@gmail.com> - 2011-07-18 14:31 -0700
  Re: Generics for a multiplevalue hashmap markspace <-@.> - 2011-07-18 14:40 -0700
  Re: Generics for a multiplevalue hashmap Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-07-18 21:00 -0300
  Re: Generics for a multiplevalue hashmap Arne Vajhøj <arne@vajhoej.dk> - 2011-07-18 23:01 -0400
  Re: Generics for a multiplevalue hashmap Roedy Green <see_website@mindprod.com.invalid> - 2011-07-19 03:59 -0700
  Re: Generics for a multiplevalue hashmap Esmond Pitt <esmond.pitt@bigpond.com> - 2011-07-19 22:24 +1000
    Re: Generics for a multiplevalue hashmap markspace <-@.> - 2011-07-19 08:31 -0700

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