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Groups > comp.lang.java.programmer > #6274

Re: Generics for a multiplevalue hashmap

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On 7/18/2011 5:31 PM, Alexis Berry wrote:
> I want to create a HashMap which has a list for each key. Therefore I can store more than one value for each key. (I know this breaks the true use of a hashmap but I want a datastruture that takes one key and hold multiple value)
>
> I thought I would be able to define:
>
> public class MultipleValueHashMap<T, java.util.List<U>>  implements Map<T, java.util.List<U>>  {
>
> ....
> }
>
> I would then construct it by "new MultipleValueHashMap<Inteteger, List<String>()"
>
> Unfortunately this does not compile. I think it might be because I am mixing generic types with real types. Am I correct?
>
> Is there a way I can use a map to store more than one value and use generics?

public class MM1<T,U> implements Map<T, List<U>>  {
...
MM1<Integer,String> mm = new MM1<Integer,String>();

or

public class MM2<T,U> extends HashMap<T, List<U>>  {
...
MM2<Integer,String> mm = new MM2<Integer,String>();

seems obvious to me.

Arne

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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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