Duplicate Keys in a Map !

Thread view:

L Clarke - 22 Feb 2006 20:30 GMT

Hi,

I know that having duplicate keys in a map is not possible, but is there
anything in java that can do such a thing?

example;

key1
- "one"
- "1"
- "uno"

key2
- "two"
- "2"
- "ect"

so by using key2 I can access all the data (return an enumeration ect)
associated with key2.

thanks in advance
lee

Reply to this Message

Vova Reznik - 22 Feb 2006 20:36 GMT

> Hi,
>
[quoted text clipped - 23 lines]
> ------->>>>>>http://www.NewsDemon.com<<<<<<------
> Unlimited Access, Anonymous Accounts, Uncensored Broadband Access

It is Map of Maps

key="key1", value - another map where keys are "one", "1", "uno",
"один", "ieden", ...

Reply to this Message

Andrew McDonagh - 22 Feb 2006 20:37 GMT

> Hi,
>
[quoted text clipped - 23 lines]
> ------->>>>>>http://www.NewsDemon.com<<<<<<------
> Unlimited Access, Anonymous Accounts, Uncensored Broadband Access

sure... have a map of arrayList objects

Reply to this Message

Scott.R.Lemke@gmail.com - 22 Feb 2006 20:39 GMT

> Hi,
>
[quoted text clipped - 18 lines]
> thanks in advance
> lee

You could have a map where the value is a datastructure that holds an
indeterminate amount of values. Or you could (ab)use a hashmap in ways
no hashmap should be (ab)used.

Reply to this Message

Jeffrey Schwab - 22 Feb 2006 20:46 GMT

> I know that having duplicate keys in a map is not possible, but is there
> anything in java that can do such a thing?

http://java.sun.com/docs/books/tutorial/collections/interfaces/map.html

Scroll down to the section on Multimaps.

Reply to this Message

bugbear - 27 Feb 2006 11:21 GMT

>> I know that having duplicate keys in a map is not possible, but is
>> there anything in java that can do such a thing?
>
> http://java.sun.com/docs/books/tutorial/collections/interfaces/map.html
>
> Scroll down to the section on Multimaps.

They mention it,
jakarta common collections DOES it:

http://jakarta.apache.org/commons/collections/apidocs-COLLECTIONS_3_1/org/apache
/commons/collections/MultiMap.html

BugBear

Reply to this Message

tom fredriksen - 22 Feb 2006 22:10 GMT

> I know that having duplicate keys in a map is not possible, but is there
> anything in java that can do such a thing?
[quoted text clipped - 13 lines]
> so by using key2 I can access all the data (return an enumeration ect)
> associated with key2.

Just use an ArrayList as the value in the Hash, then you iterate the AL
when its returned.

/tom

Reply to this Message

Roedy Green - 24 Feb 2006 13:27 GMT

>I know that having duplicate keys in a map is not possible, but is there
>anything in java that can do such a thing?

sure a HashMap where the value is an array or ArrayList of the
duplicate values. When you discover the dup, you have to manage it
yourself by adding your element to the array/ArrayList/Collection

HashMap just hands you back the list of duplicates.

Signature

Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

Reply to this Message

Duplicate Keys in a Map !

Free Magazines